2008 STRUCTURAL DESIGN ANALYSIS OF THE MAIN …ottawa.ca/cs/groups/content/@webottawa/documents/pdf/mdaw/mdq5/... · • Equivalent stress checks using the Limit States Design

ADJELE IAN ALLEN RUBEL I L IMITED CONSULTING ENGINEERS OTTAWA / TORONTO 75 Albert Street, Suite 1005, Ottawa, ON K1P 5E7 tel (613) 232-5786 fax (613) 230-8916 email [email protected]

2008 STRUCTURAL DESIGN ANALYSIS

OF THE MAIN BOX GIRDER FRAMES

LANSDOWNE PARK

OTTAWA CIVIC CENTRE & NORTH SIDE STANDS

for

CITY OF OTTAWA

prepared by ADJELEIAN ALLEN RUBELI LIMITED

CONSULTING ENGINEERS

NOVEMBER 2008

Ottawa Civic Centre & North Side Stands 2008 Structural Design Analysis


2008 Structural Design Analysis AAR Reference No. 3061-34 INDEX PAGE

1.0 Executive Summary 1

2.0 Scope of Work 3

3.0 Building Description 5

4.0 Building Operational Modes 7

5.0 Existing Loading Components 7

6.0 Structural Design Analysis Methodology and Results 16

7.0 Conclusions and Recommendations 28 Appendix A – Computer Model Appendix B – Building Plans and Elevations Appendix C – Loading Diagrams Appendix F – Tables & Figures

Ottawa Civic Centre and North Side Stands 2008 Structural Design Analysis Page 1 of 30


1.0 EXECUTIVE SUMMARY Since the completion of construction of the Civic Centre at Lansdowne Park in 1967, there have been numerous changes, additions and repairs to this facility. In addition, codes and standards have changed in the 41 years of the existence of the Civic Centre. Further, there has recently been considerable interest in the redevelopment of all of Lansdowne Park, including the Civic Centre, together with the real possibility of professional football returning to this facility as a result of a conditional granting of a CFL franchise to a Proponent in Ottawa. As a result of the above, the following questions were being asked:

• Does the building structure, with all the changes, additions, and repairs, still comply with current codes and standards, specifically the 2006 Ontario Building Code?

• Are there any restrictions or cost impacts in the redevelopment of the Civic Centre and in the Lansdowne Park lands adjacent to the Civic Centre?

To respond to these questions, Adjeleian Allen Rubeli Ltd. was commissioned by the City of Ottawa to undertake a limited investigation of the structural capacity of the primary structural framing of the Civic Centre and, in addition, to advise on the limitations, if any, to its on going uses as originally intended, and restrictions on development in the near vicinity of the Civic Centre. The report provides details on all of the loading conditions including additional loading due to the many changes and additions over the years that have an impact on the primary structure, consisting of the main box girder arch frames. The structural analysis was undertaken for gravity loads only and did not include lateral loads. The findings from the structural design analysis and investigation are as follows:

• The dead load of the precast concrete seating reported on the original structural steel design detail drawings is significantly lower than the weight identified in the original precast concrete shop drawings. The weight of seating used in the steel design was 80 psf (3.84 kPa), whereas the precast shop drawings indicate a weight varying between 101 to 106 psf (4.85 kPa to 5.09 kPa), which was confirmed by site measurements.

• There are currently three operational modes for the facility, noted as: - Fall stadium occupancy with partial snow load. No arena

occupancy. - Winter arena occupancy with snow load. No stadium occupancy. - Occupancy of the arena and stadium simultaneously (no snow on

roof).



• Equivalent stress checks using the Limit States Design approach of the 2006 Ontario Building Code (OBC) indicated that with the exception of one element, all elements of the main box girder arch frames meet the requirements of the 2006 OBC for gravity loads. However, for all operational modes involving the full occupancy of the stadium seating, the ratio of load to resistance of the stadium raker beam exceeded acceptable code values at mid-span, in accordance with the provisions of the 2006 OBC, by a factor of 1.14 or 14% in the tension zone at the bottom flange. The ratio of load to resistance of the top flange exceeded acceptable code values in compression by 7% under the governing load combination.

Further, a review of the impact of future development on the structural design gave rise to the following comments:

• For full use as a stadium, strengthening of the stadium raker beam is required to meet the 2006 OBC. Temporary loading restrictions are recommended in the interim until remedial work is undertaken.

• If minor local alterations or changes are made to the facility, then a seismic upgrade of the structure would not be required according to the OBC.

• If a major change or addition is made that has an impact on the structure, a seismic upgrade to meet the intent of the seismic provisions of the 2006 OBC would be required.

• The roof is designed for wind swept conditions resulting in a reduced design snow load. This is permitted under today’s OBC as well as previous codes. Any new adjacent building, which is higher than the stadium roof, must be located such that the distance between the two buildings is 10 times the difference between the elevation of the high roof of the new building and the top of the full snow depth on the stadium roof.



2.0 SCOPE OF WORK Adjeleian Allen Rubeli Limited (AAR) was retained by the City of Ottawa to evaluate the structural adequacy of the primary structure of the Lansdowne North Side Stands/Civic Centre under current 2006 Ontario Building Code (OBC) for compliance under gravity loads including the impact of all of the major changes and additions that have been made subsequent to the initial construction of this facility. The focus of this examination is the primary structural elements of the Civic Centre, consisting of the 3 pin box girder arch frames and their foundations. A total of eight (8) box girder frames exist, for which the analysis will focus on one frame only under various loading combinations. The scope of work for the structural evaluation can be outlined as noted below:

I. Undertake a review of existing and available documentation:

• Review of the design drawings of the original building and alterations including:

- Architectural drawings by Gerald Hamilton & Associates Architects and Craig & Kohler Associated Architects.

- Structural steel design drawings and shop drawings by Dominion Bridge Company Limited.

- Precast concrete shop drawings by Wilson Concrete Products. - Structural concrete drawings and alteration drawings by Adjeleian

and Associates Inc.

• It should be noted that the above noted drawing sets are not complete and various drawings are not available for review.

• Review of available AAR files, documentation and reports from the time of construction to present day with the intent of determining the current loading on the structure.

• Site observations and measurements of the existing conditions in order to identify and record dead and live loads on the existing structure.

II. Undertake and analyze a computer model of the primary structural elements of the building using three dimensional structural design software.

• Analyze the structure under current loading conditions and provide comments with respect its structural capacity in conjunction with the current 2006 OBC.

• The design analysis is limited to gravity loads only. Lateral loading such as wind and seismic loads will be discussed from a general point of view and is addressed separately.



• Wind uplift on the roof was from the original Dominion Bridge Company design documents as the current Ontario Building Code requirements do not apply to this structure’s configuration.

• The snow load for the stadium roof was based on the requirements of the 2006 Ontario Building Code under windswept conditions. It is our opinion that windswept conditions were assumed by Dominion Bridge Company for the original stadium roof design. For snow loading on the upper stadium concourse and arena roof, it was determined that the Ontario Building Code requirements are not appropriate for the geometric conditions of this roof structure. It was decided that an appropriate design drifting snow condition would be the on-site conditions measured in March of 2008, for the upper stadium concourse and arena roof. A visual representation of the loading is presented in Appendix C.

• It should be noted that the design analysis is limited to the primary structure only. Secondary structural elements are excluded and are only considered as load transfer elements to the primary structure.

III. Provide structural comments, recommendations and guidelines for the future sustainability and use of the Civic Centre and North side Stands:

• Provide structural comments regarding the existing load restrictions on the Civic Centre building and potential new load restriction scenarios.

• Provide structural comments regarding potential future development of the Civic Centre as well as the development of the adjacent areas and their effects on the exposed conditions of the building and the modifications to the applied wind and snow loads.

• Undertake a conceptual structural review of the existing lateral force resisting system for seismic and wind loads and provide comments as to current building code adequacy. Design analysis and structural modeling of lateral loads is not included in this scope of work.



3.0 BUILDING DESCRIPTION The Ottawa Civic Centre was constructed in 1967. The Complex is a multi-functional facility incorporating an indoor arena and exterior stadium with an associated seating capacity of approximately 9,900 and 14,600 respectively. The facility also includes 30,000 square feet of exhibition halls and assembly halls, service spaces, shipping and receiving, exterior access ramps and steps, and concourse exhibition areas. The primary structural frame is made up of eight 3 pin box girder arch frames with a 162ft (59m) cantilevered roof over the stadium seating. Each box girder is made up of eleven individual steel girder segments, site assembled by bolting, that were designed and manufactured by Dominion Bridge Company Limited. The box girders are named A through H, where A is located on the east side (Queen Elizabeth Parkway) and H is located on the west side (Bank Street). Each primary box girder is composed of the following elements:

• Roof box girder, included the back leg on the north side of the building and the cantilevered roof over the stadium.

• Arena raker beam, located on the north side of the arena, supporting the arena precast concrete seating.

• Stadium raker beam, located on the north side of the stadium, supporting the stadium precast concrete seating.

• Refer to Appendix B for corresponding plan and elevation drawings. As noted above, the primary structure is a 3 pin arch, where the pins are located at the bottom north end of the roof box girder, at the bottom south end of the stadium raker beam and at the intersection of the roof box girder and the stadium raker beam. The foundations of the box girder frames consist of reinforced concrete foundations, constructed partially below grade, and located at the base of all three box girder members. The foundations of the roof box girder and stadium raker beam, at the north and south of the building respectively, are joined by post tensioned cables extending below grade. In addition to the primary structure, secondary structural elements are found throughout the Civic Centre, including but not limited to:

• Upper stadium concourse (USC) and arena roof (AR), located at the same elevation, below the centre pin location. These secondary structural elements are suspended from the roof box girder and the stadium raker beam. The USC and AR consist of structural steel framing and structural steel hangers. The USC includes a concrete topping.



• Lower stadium concourse (LSC), located at the south end of the stadium raker beam, suspended from the stadium raker beam. The LSC consists of structural steel framing with a concrete topping and structural steel hangers.

• Upper arena concourse (UAC), located at the north end of the roof box girder, mainly suspended from the roof box girder and the arena raker beam. The UAC consists, in majority, of structural steel framing with a concrete topping. Between B and C, the UAC consists of a reinforced concrete frame bearing on concrete foundations. On line A, G and H, the UAC is partially supported by concrete columns bearing on concrete foundations.

• Lower arena concourse (LAC), located at the south end of the stadium raker beam, below the stadium seating. The majority of the LAC is not supported by the stadium raker beam or the primary structure.

• Main stadium roof, located above the stadium seating, spanning between the roof box girder cantilevers. The main stadium roof consists of structural steel joists supporting a steel deck.

• The building has undergone several upgrades over the years of occupancy, including the addition of Arena Corporate boxes, Stadium Corporate boxes and upgrades to the stadium and arena press boxes.

The structural steel of the box girder frames have been inspected periodically with the conditions reported in various reports, such as the 2007 and 2008 structural adequacy inspections.



4.0 BUILDING OPERATIONAL MODES The original building design imposed certain operational restrictions on the use of the facility. There were three operational modes established for the building which remain in place today. These three modes of operation are as follows:

• Stadium occupancy in the fall with partial snow load on the roof (30% of design snow load), with no arena occupancy.

• Arena occupancy in winter with no stadium occupancy.

• Arena and stadium occupied simultaneously with no snow on the roof. 5.0 EXISTING LOADING COMPONENTS In order to properly construct a computer model of the existing structure and comment on its structural adequacy related to the 2006 OBC, the inputs can be divided into two categories:

• Structural Geometry

• Applied Loads The structural geometry consists of the overall layout of the structure’s primary and secondary elements and the interaction between them. For the most part, these items were obtained by our review of the design drawings, for both the original construction and any subsequent additions/modifications. In addition to the overall layout and dimensions, cross sectional properties and material properties were also established. This category is used to assess the structure’s load carrying capacity or resistance. The as-built geometry was not field verified and dimensions used in the structural design analysis were taken from the available drawings. The second category is related to the applied loading on the building. For the purposes of this report, only gravity loads were considered in the analysis, which would include:

• Dead Loads

• Live Loads

• Wind Loads (Uplift)

• Snow Loads These loads contribute to the capacity demand of the structure. Section 6.0 will explore the concept of capacity versus demand in greater detail. With the aim of determining the applied loads on the structural elements, a review of the original design documentation was undertaken in order to extract the assumed loads or extrapolate the applied loads based on our understanding of the structural framing. The originally assumed loads were reviewed and modified, where required, to suit the



current use and condition of the building. Where design information was not available from the drawings, site review was undertaken to provide adequate information in order to produce realistic design loading parameters. It should be noted that the original drawings are limited and complete information is not available. Therefore, our structural review is limited to our understanding of the available information. As outlined in the scope of work, only one of the eight box girder frames is to be analyzed in-depth. As such, all the loads were determined specifically for the one section to be studied. A general overview of the original structural steel shop drawings by Dominion Bridge Company Limited showed the box girder frames to be equal in terms of cross sectional properties. Further, the only notable difference between the box girder frames is the connection points for the secondary structural elements. Based on our understanding of the existing building and the available documentation, it is our opinion that the box girders D and E are representative of the highest loaded girders due to the applied loads and supported elements. As such, box girder E was selected as the section to consider in the detailed analysis. The following sections describe the significant loads applied within the design analysis. Appendix C shows an illustrated summary of the applied loads described below. For clarity, only the most significant loads were included on the illustrations as well as the sections below.

5.1 Dead Loads To facilitate the proper creation of a structural model of the existing building, the existing dead loads were determined. Due to the multitude of changes, modifications and additions undertaken over the years, the original design dead loads were found to differ with respect to the in-situ dead loads applied to the primary structure. The following identifies the most significant dead loads as identified through our review.

5.1.1 Box Girder Structural Steel Through our review of the Dominion Bridge Company Limited structural steel shop drawings, the cross sectional properties of the box girders sections were determined. Therefore, their self-weight was calculated and incorporated into the model accordingly.



5.1.2 Secondary Structural Steel Framing Dead loads, associated with floors and roofs, applied to the box girder frames include:

• Upper stadium concourses.

• Lower stadium concourse.

• Arena roof.

• Upper arena concourse.

• Exterior arena promenade.

• Stadium roof.

• Sloped siporex roof. The upper stadium concourse consists of short span joists suspended between welded wide flange (WWF) beams. The flooring is composed of a steel deck, insulation, waterproofing membrane and a concrete topping averaging 2 ½” in thickness based on field observations during test openings undertaken in 2008. The lower stadium concourse consists of structural steel framing with a similar topping system to that of the upper stadium concourse. The arena roof is comprised of steel deck, insulation and a bituminous roof system supported by short span steel joists and structural steel beams. This roofing system was replaced in 2000/2001 with an applied dead load comparable to the original design dead load. The upper arena concourse consists of a 2 ½” concrete topping on steel deck supported by long span steel joists and structural steel members. The upper arena concourse between box girders B and C consists of a reinforced concrete slab supported on reinforced concrete columns, walls and foundations. The concrete portion of the upper arena concourse is independent of the remaining structure and does not impose gravity loads on the primary box girder frames. In addition, the structural steel framing along A, G and H is partially supported by reinforced concrete columns bearing on reinforced concrete foundations. The exterior arena promenade is composed of a reinforced concrete slab with a cantilevered section at the north end. The elevation of the exterior arena promenade is concurrent with the upper arena concourse. The sloped siporex roof acts as a snow and rain cover to the exterior arena promenade and the upper arena concourse. The sloped roof structure consists of a siporex roof supported on structural steel framing



spanning between the box girder frames. The roofing over the siporex was modified in 1992, with the addition of self weight load on the roof.

5.1.3 Masonry Block Walls Masonry block walls are found throughout the building. Their locations were identified on the original architectural drawings and confirmed on site. The heights and wall thickness’ were determined on site. The most prominent locations, which contain block walls applying dead loads to the primary structure, are listed below.

• Upper stadium concourse concessions and washrooms.

• Lower stadium concourse concessions and washrooms, including the full height partition wall between the concourse and the arena.

• Upper arena concourse concessions and washrooms.

5.1.4 Precast Concrete Seating The arena and stadium seating consist of precast concrete seating spanning between the arena and stadium raker beams, respectively. The principle cross section is composed of a T-section with an upstand leg at the rear of the section. The original precast concrete shop drawings by Wilson Concrete Products were available for review. In addition, design loads were indicated on the Dominion Bridge Company Limited’s structural steel shop drawings. Based on our review of the available documentation, discrepancies were noted between the loads provided by Wilson Concrete and Dominion Bridge. As such, an on-site investigation was undertaken to field measure the in-place concrete section to determine the in-situ applied loads. Based on our site measurements, the in-situ precast concrete seating matches the details provided in Wilson Concrete Products originally shop drawings. The dead loads used in our structural analysis were those obtained from the site and match the Wilson Concrete Product shop drawings, which exceed the design loads identified on the Dominion Bridge shop drawings. The precast concrete seating weights are as follows:

• Wilson Concrete Products shop drawings (confirmed by site measurements) 101 to 106 psf

• Dominion Bridge Company design drawings: 80 psf



In addition to the precast concrete, the weights of the hollow concrete steps in the aisles and the seats (plastic and metal) were estimated and included in the applied dead loads.

5.1.5 Cast-in-Place Concrete Structures These concrete elements are located throughout the stadium and arena and include miscellaneous details such as the arena and stadium vomitory entrances, concrete cover on the structural steel hangers supporting the arena roof structure, the concrete curb separating the arena roof and the upper stadium concourse as well as miscellaneous concrete walls and concrete stairs within the arena seating. Locations, dimensions and layouts were determined from the original architectural and structural drawings with confirmation from our on-site review. 5.1.6 Arena Movable Seating As part of the original construction of the arena, portions of the arena seating are capable of being lifted out of place and suspended from the arena roof and upper stadium concourse for certain events held within the arena. There are two sections of movable seating in the arena, one on the south side of the arena and one on the north side of the arena, accessed from the lower and upper arena concourses respectively. Both sections of movable seating span between gridlines E and D. These movable sections were upgraded for fire protection in 1992 and a corresponding updated load was provided in a letter from Kone Cranes in association with the installation of new hoists. In addition to these new loads, a structural steel safety device was installed on the north side of the arena roof as a failsafe to hold the movable seating in place once raised. No specific data for the load associated with this safety device has been found; however, based on our field observations, an estimated self weight was established for use in the structural model.

5.1.7 Arena Clock The arena clock is suspended from the upper stadium concourse directly above center ice. Its self weight was determined from discussions with Lansdowne Park facility staff to be approximately 4000lb.



5.1.8 Arena Concert Rigging A structural review of the arena roof and upper stadium concourse structural steel framing was undertaken in 1992 by Adjeleian Allen Rubeli Limited for the future use of concert rigging to be suspended from above. The structural directions provided included the maximum allowable loads in conjunction with various layout options, which were included in our structural design analysis. 5.1.9 Arena Boxes The arena press boxes (originally named Arena Gondola) were constructed during the original construction of the building. These boxes are suspended on the north side of the arena, from the arena roof structure. Available drawings and information are incomplete and their original construction details were not available for review. The arena press boxes were expanded in 1991, with the structural design undertaken by Adjeleian Allen Rubeli Limited. Dead loads and self-weight data were obtained from the arena press box expansion structural drawings and carried over to the original arena press boxes. Originally, access to the arena press boxes was gained by means of a pair of catwalks leading from the top of the north arena seating to the boxes. These catwalks are no longer in use and the portion leading to the arena seating has been removed. The design of further additions to the arena press boxes were undertaken by Adjeleian Allen Rubeli Limited in 1992. The arena corporate box expansion included a layout where the boxes extended to the south of the arena, creating a U-shape for the boxes. Dead loads were clearly identified on the structural drawings for the expansion and were used in our design analysis. It should be noted that the boxes located on the south side of the arena, accessible through the lower arena concourse, do not impose loads on the primary structure under review as they are supported on the concrete foundations below.

5.1.10 Upper Arena Concourse Exterior Wall The wall separating the upper arena concourse and the north exterior promenade is a steel frame wall with glazing throughout. The associated dead loads were estimated and included in the structural design analysis.



5.1.11 Stadium Boxes The stadium press boxes (originally named Stadium Gondola) are suspended from the stadium roof and are located approximately half way down the cantilevered roof. These press boxes were included in the original construction in 1967 and later expanded; however, incomplete drawings and information are available for our review. The dead loads associated with the stadium press boxes were estimated using a combination of field observations, documentation regarding proposed expansions of the stadium press boxes (not constructed) and the available information of the arena boxes. The stadium corporate boxes (originally additional stadium press boxes) are located at the top end of the stadium seating and were designed by Adjeleian Allen Rubeli Limited in 1988. The ceiling of the stadium corporate boxes is suspended from the stadium roof. The walls, glazing and floors are bearing on the on the stadium precast concrete seating. Additional boxes were constructed in 2003 between A to B and G to H. However, these most recent additions differ from the remaining corporate boxes as they do not have a ceiling structure suspended from the stadium roof and are fully bearing on the stadium precast concrete beams. The corresponding dead loads were calculated based on the structural and architectural drawings and details were confirmed on-site.

5.2 Live Loads The live loads considered under the structural design analysis relate to occupancy loading only. Wind loads and snow loads are considered as independent loads under the 2006 OBC and are discussed separately. Refer to table 5.1 in Appendix D for the distribution of principle live loads throughout the building, as applied to the primary box girder frames. The loads presented above are based on the 2006 OBC; however, it should be noted that the applied live loads under the 1965 NBC are identical to those in the current code Further, occupancy live loads may be reduced to account for large tributary areas supported by the structural elements. Based on our understanding of the building codes, the live load reduction factors are essentially the same between the 1965 NBC and the 2006 OBC, with minor variations, which can be accounted for through the changes to the empirical equations from the imperial system with the conversion to the metric system. The live loads provided in the above table



are full, unreduced, live loads. Where live load reduction is available, it was incorporated into the design analysis. It is therefore our opinion that no significant changes to the applied live loads have occurred between the original construction, under the 1965 NBC, and the current 2006 OBC. 5.3 Wind Loads In order to incorporate all the gravity loading effects on the primary structure, wind loads were considered, mainly as uplift forces inducing stresses in the primary box girder frames. As noted previously in this report, lateral design analysis is not included in the scope of work. Uplift forces were considered on the stadium roof as well as the arena roof and upper stadium concourse, due to their exposed conditions. In addition, wind loads were applied to the roof box girder's sloped siporex roof on the north side of the building as well as the glazing wall separating the upper arena concourse from the exterior promenade. The stadium roof structure over the north side stands is unusual in its size and configuration and represents a roof profile for which code wind pressures are currently not available. For the purposes of our structural design analysis, wind uplift loads were based on the wind loads noted on the Dominion Bridge Company drawings. These values appear to be conservative but cannot be confirmed by the provisions of the Ontario Building Code at this time. However, based on our knowledge of the building code wind loads and their application to complex structural shapes, such as the one under consideration, it is our opinion that further investigation is required, by means of detailed wind tunnel testing, for the Civic Centre structure. This issue will be discussed later in this report. 5.4 Snow Loads The basic roof design for snow loads as provided in the Ontario Building Code has not substantially changed from the 1965 NBC to the 2006 OBC. The basic roof snow load from the 1965 NBC is 48 psf (2.3 kPa) and from the 2006 OBC is 2.32 kPa. For roofs meeting the code criteria for “exposed to wind”, the design snow load is reduced by an exposure wind factor of .75 for both the 1965 and 2006 OBC. Incorporating these values into the structural design, the stadium roof snow load utilized was 1.84 kPa (38 psf), whereas the original Dominion Bridge Company’s stadium roof snow load consisted of 36 psf.



However, there are two major differences in the two codes, to be noted as follows:

• A roof size effect which increases design snow loads for both standard roofs and wind exposed roofs. The roof size of the stadium roof is less than the tipping point which would trigger higher snow loads for the wind exposed condition. Therefore, no increase in loading is required.

• Snow drifting as a result of a lower roof adjacent to a higher roof is considerably higher in the 2006 OBC compared to the 1965 NBC. The roof over the arena and upper stadium concourse would be required to support a significantly larger drifting snow load if designed under the 2006 OBC compared to the design of the existing roof which was in accordance with the 1965 NBC. As such, we incorporated in-situ snow loading as described below.

In early March of 2008, following the last major snow storm of the year, the in-situ snow loads on the upper stadium concourse and arena roof were measured. At the time of the measurement of snow depths and density on the arena roof, the accumulation of snow on the ground and roofs of buildings in Ottawa was generally thought to represent the 1 in 50 year design condition for snow. This was certainly evident in the snow load measured on the stadium roof, which actually exceeded the 1 in 50 year design snow load by as much as 12% in some areas. We concluded that it was reasonable for this study to use the snow load data determined for the arena roof as the snow loading condition for the model. It should be noted; however, that there was evidence of the prevailing winds during the 2007/2008 winter season predominately from the north. Should prevailing winds during large snow storms be from the south, significantly higher snow loads, compared to those measured in March of 2008, could occur. It is our opinion that for extended use of this facility, a wind tunnel test combined with currently available engineering evaluation techniques should be undertaken to confirm appropriate design snow drifting loads for the roof over the arena.



6.0 STRUCTURAL DESIGN ANALYSIS METHODOLOGY AND RESULTS The principle goal of this project was to undertake a structural design analysis based on a computer model of the existing Civic Centre, with appropriate loads and load combinations, and evaluate its structural load carrying capacity under the provision of the 2006 O.B.C and related CSA standards. The computer model created consists of a three dimensional model of the existing Civic Centre, simplified for the analysis of the primary box girder frames. Select secondary structural elements were included in the model for the purposes of load transfer only and were not analyzed under this scope of work. The software package utilized was ETABS, a three dimensional, finite element modeling program used for the design and analysis of complex structural building systems. Member geometry and element cross sectional properties were incorporated into the model accurately based on the available information, derived from the original design drawings and documentation as well as on-site review of the building’s construction and as-built details. Refer to Appendix A for sample illustrations from the software package. All the applied loads, including dead, live, wind, and snow loads were determined as discussed in the previous sections and applied to the structural model to perform the analysis in accordance with the 2006 OBC.

6.1 Design Approach and Computer Modeling In conjunction with the three dimensional computer model, the structural design aspects were addressed under the followings standards, all under the umbrella of the 2006 Ontario Building Code.

• CAN/CSA-A23.3-04 Design of Concrete Structures

• CAN/CSA-S16-01 (R2007) Limit States Design of Steel Structures As previously noted, the original construction of the Civic Centre is in 1967. As such, the manufacturing processes related to structural steel fabrication differed significantly from the standards and parameters used today. Based on our review of the original documentation, the structural steel grade is based on the G40.12 and S16-1965 specifications. The associated material properties were utilized in the structural model in order to properly calculate the member capacities. The structural design analysis was based on a steel yield strength of 300 MPa (44 ksi), as provided by the CSA G40.12 in force in 1967. However, for steel plate thicknesses greater than 1 ½” (40mm), the yield strength is reduced to 276 MPa (40 ksi). This reduced value of steel yield strength was also included in the analysis, where required. It is our recommendation that the in-situ steel yield



strength be established in order to produce a more accurate computer model of the existing structure. The typical testing method would be to remove sample coupons of steel from the existing structure in areas of low stress and subject them to tensile testing to establish the true yield strength. Once the building geometry and member properties we’re input into the computer model, in conjunction with the applied loads, the structural design analysis was carried out. The design approach set forth in the 2006 OBC consists of limit states design (LSD), defined in the 2006 OBC as follows:

[the] conditions of a building structure that result in the building ceasing to fulfill the function for which it was designed (Those limit states concerning safety are called ultimate limit states and include exceeding the load-carrying capacity, overturning, sliding and fracture; those limit states that restrict the intended use and occupancy of the building are called serviceability limit states and include deflection, vibration, permanent deformation and local structural damage such as cracking; and those limit states that represent failure under repeated loading are called fatigue limit states)

Our analysis will focus on the ultimate limit states (ULS) for strength and the serviceability limit states (SLS) for deflection. Fatigue limit states, produced under cyclical loading, is not included in the scope of work. Limit states design is a modernization and rationalization of well established engineering knowledge. Load factors are introduced to the applied loads, generally to increase the loading effects due to potential variability in the loading patterns. The resulting value is defined in the 2006 OBC as the factored load. Similarly, material factors are introduced to reduce the load-carrying member capacity to account for variations in material properties and the manufacturing processes. The resulting value is defined in the 2006 OBC as factored resistance. In order for the structure to be in accordance with the 2006 OBC ultimate limit states, the factored resistance must be greater or equal to the factored load. The ratio of the factored load to the factored resistance is identified as the Interaction Value. If the Interaction Value is equal to or less than 1.0, it meets the requirements of the 2006 OBC. If the Interaction Value is greater than 1.0, it does not meet the requirements of the OBC. A normal Interaction Value up to 1.02, where the factored loads exceed the factored resistance by 2%, is generally considered acceptable in the assessment of existing structures. Also, the serviceability limit states must be checked to ensure that the calculated deflections of the structural elements must be within the limits identified in the



2006 OBC. Both the ULS and SLS requirements were explored in our analysis, for the primary structural elements. The original structural design was undertaken using the previous methodology known as allowable stress design, where the designer ensures that the stresses developed in a structure due to service loads (unfactored loads) are at a defined level below the elastic limit of the material to ensure a suitable factor of safety against failure. The allowable stress design methodology was phased out and eventually replaced, in Canada, by the limit states design philosophy. It is important to note that our entire structural design analysis is based on the concept that the primary structural elements are in good condition with no loss of resistance due to deterioration or any other factors. This assumption is, in our opinion, reasonable through the continued rigorous maintenance plans that the City of Ottawa has undertaken at the noted building. In order to continue to consider the structure in good condition, regular maintenance and future investigations are recommended, as discussed in the final section of this report.

6.2 Structural Elements and Results As outlined earlier in this report, our structural design analysis is limited to the primary structure only. The primary structure consists of the following elements:

• Box girder arch frame including the roof box girder, arena raker beam, the stadium raker beam and the main bearing pins.

• Reinforced concrete foundations at the base of the box girder frame.

• Post tensioned ties connecting the north and south foundations. The following sections outline the results obtained from the structural design analysis with regards to both ultimate limit states and serviceability limit states.

6.2.1 Ultimate (Strength) Limit States 6.2.1.1 Load Combinations The two principle occupancies of the building, relative to the primary structure, consist of arena loading and stadium loading. In conjunction with these occupancies, a variety of loading patterns exist in regards to dead, live, wind and snow loads depending on the type of event occurring and the time of year. The different loads and their breakdowns are discussed in section 5.0. In order to properly assess the condition of the primary structure under all the various loading conditions, we have used the 2006



OBC load combinations for ultimate limit states design review. These load combinations are composed of principle loads and companion loads where the companion loads carry smaller load factors to illustrate the low statistical probability of the full principle load and full companion load occurring simultaneously. There are a number of load combinations to be considered to take into account the operational use of the facility as well as the individual effects of dead load (D), live load (L), snow load (S) and wind load (W). In the cases where snow loads are considered for the fall season, 30% of the design snow load is used in the analysis to represent a realistic snow loading condition in conjunction with the potential occupancy of the stadium. The indicated value of 30% is also identified in original Dominion Bridge Company documentation and has therefore been carried forward in the present day load combination. We have grouped these load combinations into 2 categories, A and B, as follows:

A. Operational Load Combinations (1 to 3) B. Additional Load Combinations of Interest (4 to 10)

The operational load conditions in category A are as noted: A.1 Fall Stadium Occupancy with 30% design snow load

(Arena not occupied). Load Combination 1. A.2 Winter Arena Occupancy with design snow load (Stadium

not occupied). Load Combinations 2 and 3. A.3 Summer Occupancy of the Stadium and Arena

simultaneously. Load Combination 4. The loading conditions in category B are presented as follows: B.1 Summer Arena Occupancy with wind uplift loading

(Stadium not occupied). Load Combinations 5 and 6. B.2 Fall Stadium Occupancy with 30% design snow load in

conjunction with the Dominion Bridge Company assumed dead loads. Load Combination 7.

B.3 Summer Stadium Occupancy (Arena not occupied). Load Combination 8.

B.4 Fall Stadium Occupancy with 30% design snow load, lower half of the stadium occupied up to row 30, minimal live load on the upper stadium concourse (1kPa) and full design live load on the lower stadium concourse (4.8kPa). The



stadium press boxes, suspended from the stadium roof are included. (Arena not occupied). Load Combination 9.

B.5 Fall Occupancy of the Stadium and Arena with 30% design snow load. Load Combination 10.

6.2.1.2 Analysis Results for the Primary Elements Table 6.1 in Appendix D contains a summary of the results of the design analysis for the selected load combinations. Interaction Values were determined at critical sections of the components of the arch structure including 4 different points along the length of the stadium raker beam. The initial results of the analysis identified one area of concern, which showed up in a number of different load combinations. The stadium raker beam at section A (mid-span) showed Interaction Values greater than 1.0 for a number of different load combinations. Table 6.1 shows the Interaction Values at the mid-span of the stadium raker beam. The remaining portions of the stadium raker beam and all of the other primary structural elements, including the roof box beam, arena raker beam, reinforced concrete foundations, the structural steel pins for the 3-pin arch and the post tension ties were all found to have Interaction Values less than 1.0. It should be noted that these ties are located below grade and have never been reviewed to assess their condition. Refer to section 7.0 for our recommendations for future investigation relative to the post tensioned ties. As such, in our opinion, these elements, except at the mid-span of the stadium raker beam, safely support the load combinations reviewed in accordance with the 2006 OBC, as indicated in Table 6.1. 6.2.1.3 Detailed Review of the Stadium Raker Beam As the stadium raker beam was the only element that had Interaction Values greater than 1.0, a more detailed review was required. Four cross section locations along the length of the stadium raker beam, identified as A, B, C and D on the building elevation found in Appendix B, were determined to be the points of highest stress, which were considered in detail in the analysis.



Table 6.1 provides the results of the mid-span location of the stadium raker beam as well as the results at the remaining locations at B, C and D. From the results, the only concern is located at the mid-span, section A, of the stadium raker beam. In the load combinations where the stadium is fully occupied (Load Combinations 1, 4, 8 and 10), the Interaction Value for the bottom flange in tension was found to be 1.14 and the top flange in compression was found to vary between 1.05 and 1.07. These values are representative of the fall and summer occupancy conditions with and without the arena included. It appears that the use of the arena simultaneously with the use of the stadium does not have a significant impact on the structural Interaction Values. We have concluded that, in our opinion, any operational use of the facility that includes full stadium occupancy results in the stadium raker beam exceeding the acceptable code values for structural resistance. 6.2.1.4 Supplementary Load Combinations A number of additional load combinations, beyond the operational load combinations, were considered to better understand the apparent conditions of the stadium raker beam, exceeding acceptable code values, particularly as this facility has been in operation for over 40 years with full stadium occupancy occurring within this time. Load Combination 7 was introduced based on our understanding of the design load conditions assumed by Dominion Bridge Company. The most important variance is noted in the assumed dead load of the precast concrete seating. The available Dominion Bridge documents indicate that the dead load of the precast concrete seating was assumed to be 80 psf. Based on our field measurements and the original Wilson Concrete Products shop drawings, the in-situ dead load of the precast concrete seating varies between 101 psf and 106 psf. Refer to section 5.1.4 for additional information. The Interaction Value for Load Combination 7 was found to be 1.06 at the bottom flange in tension and 1.00 for the top flange in compression. It should be noted that original Dominion Bridge Company documentation identifies Overstress Values of up to 1.04 for their design analysis for similar sections and loading conditions. It is our opinion that the results of our analysis are consistent with



the original Dominion Bridge Company’s design and variations in the results can be attributed to the design methodology, Working Stress vs. Ultimate Limit States, as well as the modifications to the relative structural steel design standards, CSA S16-1965 vs. CSA S16-01 (R2007). Load Combination 8 consists of the full stadium occupancy without the arena occupancy. The Interaction Values for Load Combination 8 were found to be virtually unchanged from Load Combination 4, which included the stadium and arena occupancy simultaneously. Therefore, our previous comments remain applicable in that the arena occupancy does not have a significant effect on the stresses in the stadium raker beam. Load Combination 9 was created in light of the results found at the stadium raker beam, where the Interaction Values were above 1.0. In order to reduce the Interaction Value to a level in accordance with the 2006 OBC, the stadium occupancy was limited to the first 30 rows of seating, coinciding with the last row of seating before the vomitories of the upper stadium concourse. As such, is it assumed that the upper stadium concourse would be closed and only minimal live load would be applied (1.0 kPa). However, in order to sustain the first 30 rows of occupancy, the lower stadium concourse would be loaded to full design live load (4.8 kPa). The structural design analysis for Load Combination 9 resulted in Interaction Values not exceeding 1.0, thus in accordance with the 2006 OBC. This loading condition is a realistic occupancy pattern for current use of the stadium, i.e. university football games, and could easily be enforced. Load Combination 10 addresses the long standing load restriction imposed on the Civic Centre building, which states that the arena and stadium are not to be occupied simultaneously when applied snow loads are present on the structure. Therefore, Load Combination 10 was based on the full occupancy of the stadium and arena in conjunction with 30% of the design snow load. The structural design analysis indicated that the Interaction Values obtained were virtually unchanged from Load Combination 1, which included occupancy of the stadium, 30% design snow load and no arena occupancy. This further reinforces the concept that the occupancy of the arena does not significantly affect the Interaction Values of the stadium raker beams.



6.2.1.5 Loading Restrictions and Remedial Action There are currently three operational conditions as outlined in section 6.2.1.1 in this report. As a result of the findings of this study, it is our recommendation that the stadium use be limited to the first 30 rows of seating with the upper stadium concourse closed, until remedial measures are taken to comply with the provisions of the 2006 Ontario Building Code. The remedial work would also allow for the removal of the long standing load restriction on the Civic Centre regarding simultaneous use of the stadium and arena during the fall and winter months. In our opinion, the two most practical concepts for remedial work would be as follows: a) Increase the load-carrying capacity of the stadium raker beam

by means of structural reinforcing. The design of structural reinforcing is outside the scope of this report; however, the concept is expanded in section 7.0.

b) Reduce the applied dead loads applied to the stadium raker beam. The principle dead loads would include the stadium precast concrete seating and the masonry block partition walls found throughout the upper and lower stadium concourses.

As noted in our scope of work, the secondary structural elements were not reviewed for their compliance with the current 2006 OBC. It is our recommendation, for a future phase of this design project, that the secondary elements, including structural steel and concrete elements, are reviewed to asses their capacity in regards to current in-situ loading conditions based on the 2006 OBC.

6.2.2 Serviceability (Deflection) Limit States In March 2008, Adjeleian Allen Rubeli Limited was on-site to review the in-situ snow loading on the stadium roof following signs of structural distress noted at the stadium corporate boxes. Water leakage/staining as well as cracks in the finishes were visible from inside and outside the boxes. Localized distress was also noted in the secondary structural steel elements above the corporate boxes. A preliminary site investigation was undertaken in March 2008 with a full investigation taken place in July 2008. Refer to the Adjeleian Allen Rubeli Limited 2008 Structural Adequacy Report dated August 2008 for a full



description of the distressed areas as well as recommended remedial details, scheduled to be undertaken in the fall of 2008. Based on our review, the applied snow loads on the stadium roof were deemed to exceed the original design snow load of the stadium roof by an average value of approximately 12%. The recommended remedial work consists of reinstatement of the damaged structural steel hangers and bolts as well as repairs and reinforcing to the open web steel joists at the stadium roof. This remedial work will reinstate the corporate boxes to their original design intent. The higher than expected snow accumulation during the past winter season, on the stadium roof caused the cantilevered portion of the roof to deflect considerably, thus lowering the ceiling of the corporate boxes to the point that the structure was no longer free to move vertically and was caught or hung-up on the adjacent structural elements and architectural finishes. Therefore, the roof hangers, which were designed to act as tension only members, were now acting under applied compression loads outside of their design intent. Although an allowance was built into the corporate box structure to sustain the anticipated roof deflections for either snow loading or stadium seating loading, the high snow loads caused deflections in excess of the design values, which restricted the free movement of the structural steel elements and in turn caused an accumulation of unanticipated stresses in the structure. It should be noted that the original design of the ceiling of the corporate boxes provided an allowance of 2 ½” (64mm) of vertical movement, a reasonable assumption considering its proximity to the support of the cantilevered roof. With the aid of the constructed computer model, deflections were calculated and recorded. Under full snow loading, the stadium roof deflection at the location coinciding with the south face of the corporate boxes was determined to be 4.7” (119mm), therefore exceeding the allowable deflection originally assumed. Based on the previous field observations and the results of the structural design analysis, the stadium roof clearly exceeded its original deflection allowance. It is our opinion that the remedial work scheduled to be undertaken will only reinstate the corporate boxes to their original design and will not prevent any future distress as was seen in the 2007/2008 winter season.



In order to properly account for future snow loading, which would approach the design snow loads, the connection details of the corporate box ceilings would require removal and replacement with new details to account for a minimum of 5” (127mm) of vertical movement. Such remedial work would include removal of the majority of finishes surrounding the south face of the corporate boxes including the suspended ceiling, partitions and windows along the south face In addition to the deflection at the location of the corporate boxes, the other noteworthy location of deflection is at the south end of the cantilevered stadium roof. Based on our calculations and design review, the deflection at the end of the roof, under full design snow loads, is approximately 31.6” (803mm).

6.3 Future Development

It is our understanding that the Lansdowne Park property and Civic Centre are part of multiple studies to assess the proposed future expansion and modifications to the existing buildings. As such, the impact of the additions and modifications, whether they are part of the existing Civic Centre structure or new construction adjacent to the existing, should be reviewed and investigation.

6.3.1 Modifications to the existing structure. The first item to consider is possible additions or modifications to the existing structure. There have been numerous additions to the Civic Centre since its construction in 1967, for which many of those have been identified and studied in this report. Up until the present time, it is our opinion that the changes undertaken have imposed new loads on the primary and secondary structure; however, these changes have not significantly affected the behaviour of the structure as a whole. Typically, a change in use or occupancy of the building, or a modification requiring large structural changes such as increasing the building’s mass significantly may require the existing structure to be updated to the most recent building code. Again, it is our opinion that the changes to date have not been significant enough to invoke such a requirement to upgrade the existing structure to the most recent OBC. Future development and expansion of the Civic Centre building may produce changes great enough to require an upgrade to the current OBC. Such an upgrade would involve a number of aspects, one being the



design verification of the existing structure under gravity loads, which was the goal of this report. It should be noted that this report only reviewed the primary structure for gravity loads and further review of the secondary elements would be required, if such changes are proposed. Additional upgrades would consist of the lateral force resisting system of the existing structure, which resist the loads applied laterally, such as wind loads and seismic loads. Significant changes have occurred to the National Building Code and Ontario Building Code relative to seismic provisions and design between the 1965 NBC and the 2006 OBC. Through expanded knowledge in the field of seismic and earthquake engineering, seismic loads are more accurately modeled and incorporated into the design of building structures. The result of this knowledge is a significant increase in the seismic requirements compared to previous versions of the OBC. In Ottawa, it is highly likely that the seismic provisions would govern over the wind loads for the noted building. The lateral force resisting system of the Civic Centre structure, in the East West direction, is comprised of a number of structural elements, including the floor diaphragms at the stadium roof and arena roof, diagonal bracing in two of the 8 bays, along the length of the stadium raker beam as well as on the bottom end (north side) of the roof box beam. In the North South direction, the lateral force resisting system consists of the 3 pinned arch itself, transferring the loads directly to the reinforced concrete foundations. In our opinion, the lateral force resisting system, particularly in the East West direction would not meet the seismic requirements of the 2006 OBC. A major renovation or alteration of the current structure for the Civic Centre would require an upgrade of the lateral force resisting system to meet the 2006 OBC seismic requirements.

6.3.2 New construction adjacent to the existing structure Not only can future expansion of the Civic Centre be a possibility, but future plans may include the construction of new buildings adjacent to the existing structure. The principle effect of future buildings would be their effect on the snow loads applied to the existing structure. The high roof over the stadium of the Civic Centre was designed assuming a wind exposed roof with a reduction in snow load. This provision of the 1965 National Building code continues essentially unchanged in the 2006 Ontario Building Code.



Under exposed conditions, the exposure factor used to calculate the design snow load is 0.75. However, for a building with an adjacent higher roof (potential new construction), the exposure factor increases to 1.0, thus increasing the design snow load by 33%. There is a further increase in loading due to the size effect of the roof area as required by the 2006 O.B.C. In order to avoid this noted increase in the design snow load, the adjacent building must be located such that the distance between the two buildings is 10 times the difference between the elevation of the high roof and the top of the full snow on the low roof. This limitation and guideline is illustrated in figure 6.1 for clarity. As long as the new structure remains below the 10:1 sloped line shown in the illustration, the exposure factor would remain unchanged. The above change in the exposure factor is a simplified expression of the possible variations in loading on the existing structure. As noted earlier in this report, the most accurate method of determining the in-situ snow and wind loads would be to undertake a full wind tunnel test. Should a wind tunnel test be completed, a multitude of potential structures could be incorporated into the wind tunnel to study the effects of future expansion and development.



7.0 CONCLUSIONS AND RECOMMENDATIONS 7.1 Structural Design Analysis A comprehensive structural design analysis, including computer modeling, was undertaken on one main box girder arch frame, more specifically girder E, which represents a typical box girder arch frame. The structural review was completed for the following primary structural elements:

• Roof box beam.

• Stadium raker beam.

• Arena raker beam.

• Pins of the arch frame.

• Reinforcing concrete foundations.

• Post tensioned ties. The structural analysis indicated that the stadium raker beam has an Interaction Value of 1.14 at section A (mid-span) for numerous load combinations, consistent for all load combinations that include full stadium occupancy. These conditions occur for various load combinations with and without arena occupancy and snow loads. It is our opinion that the concerns related to the Interaction Values above 1.0 stem primarily from the in-situ dead loads of the stadium precast concrete seating, which exceed the original design values, based on our understanding of the available documentation. All remaining primary structural elements were found to be in accordance with the 2006 OBC with no structural concerns. In order to address the concerns with the stadium raker beam, it is our opinion that a temporary load restriction be enforced until remedial work may be undertaken. The temporary load restriction is in addition to any existing load or occupancy restrictions applied to the Civic Centre building. We recommend that stadium occupancy be limited to the first 30 rows of seating for any event occurring in the stadium. As such, the upper stadium concourse would be closed during these events and the lower stadium concourse would be open for concessions, washrooms and exiting of the first 30 rows of seating. In order to remove the new and long standing load restrictions on the stadium, it is our opinion that remedial work would be required to bring the structure in accordance with the current 2006 OBC for gravity loads.



In our opinion, the two most practical scenarios would be as follows:

1. Reinforce the existing structural steel stadium raker beam in order to increase its load carrying capacity.

2. Reduce the applied dead load in order to recreate to original Dominion Bridge Company’s assumed dead loads. This would include a full removal of all the precast concrete seating in the stadium and replacement with a lighter and stiffer designed section. Other secondary elements such as the masonry block partitions would also be removed and replaced with lighter materials.

With regards to the serviceability (deflection) limit states, it is our recommendation that remedial work be taken at the stadium corporate boxes, in addition to the work scheduled for fall 2008, to address future deflection of the stadium roof. The currently scheduled work will only reinstate the corporate boxes to their original design concept, which is not adequate to sustain future deflections of the stadium roof.

The recommended remedial work would include the removal of the majority of finishes surrounding the south face of the corporate boxes, including the suspended ceiling, partitions, and windows along the south face in order to install new structural connections between the box ceiling and framing.

In addition to the above structural recommendations, there are a number of additional recommendations for future structural investigations that should be undertaken to further clarify the existing structure’s behaviour. Any future information and design data gathered from any of the recommendations noted below may be incorporated into an updated structural model to further refine the results.

Wind tunnel testing to establish more accurate design wind pressures as well as design snow loads due to the building’s complex geometry.

Testing of small samples of the structural steel should be undertaken to establish the in-situ yield strength of the existing structural steel elements.

A structural review and investigation of the existing post tensioned ties, below grade, to assess their current condition and identify potential deterioration.

A structural design analysis of all secondary structural elements based on the most up to date Ontario Building Code. As previously noted, this report only addresses the primary structural elements of the box girder arch frames.

APPENDIX A

COMPUTER MODEL

APPENDIX B

BUILDING PLANS AND ELEVATIONS

APPENDIX C

LOADING DIAGRAMS

APPENDIX D

TABLES AND FIGURES

Table 5.1: Live Loads per the 2006 OBC Area Live Load (kPa) Live Load (psf)Stadium Seating 4.8 100Arena Seating 4.8 100Upper and Lower Stadium Concourse 4.8 100Arena Roof 1.0 20Upper Arena Concourse 4.8 100Exterior Promenade 4.8 100Arena Press Boxes - Floor 2.4 50Arena Press Boxes - Roof 1.0 20Stadium Press Boxes - Floor 2.4 50Stadium Press Boxes - Roof 1.0 20Stadium Corporate Boxes - Floor 2.4 50Stadium Corporate Boxes - Roof 1.0 20Catwalks at boxes 4.8 100

Table 6.1: Load Combinations

Reference Load Combination Description Roof Arena Pins Footings and Box Beam Section A Section B Section C Section D Raker Beam Post-Tensionned Ties

1 1.25D + 1.5L(Stadium) + 0.5[0.3S] Fall stadium occupancy with 30% design snow load. PASS 1.14T PASS PASS PASS PASS PASS PASSArena not occupied 1.07C

2 1.25D + 1.5L(Arena) + 0.5S Winter arena occupancy with design snow load. PASS PASS PASS PASS PASS PASS PASS PASSStadium not occupied.(combo 1)

3 1.25D + 1.5S + 0.5L(Arena) Winter arena occupancy with design snow load. PASS PASS PASS PASS PASS PASS PASS PASSStadium not occupied.(combo 2)

4 1.25D + 1.5L(Stadium) + 1.5L(Arena) Summer occupancy of the stadium and arena PASS 1.14T PASS PASS PASS PASS PASS PASSsimultaneously. 1.05C

5 0.9D + 1.5L(Arena) + 0.4W Summer arena occupancy with wind uplift loading. PASS PASS PASS PASS PASS PASS PASS PASSReduced dead load on roof box beam cantilever only.(combo 1)

6 0.9D + 1.4W + 0.5L(Arena) Summer arena occupancy with wind uplift loading. PASS PASS PASS PASS PASS PASS PASS PASSReduced dead load on roof box beam cantilever only.(combo 2)

7 1.25D + 1.5L(Stadium) + 0.5[0.3S] Fall stadium occupancy with 30% design snow load in PASS 1.06T PASS PASS PASS PASS PASS PASSconjunction with the Dominion Bridge Company assumed 1.00Cdead loads.

8 1.25D + 1.5L(Stadium) Summer stadium occupancy. PASS 1.14T PASS PASS PASS PASS PASS PASSArena not occupied 1.05C

9 1.25D + 1.5L(Stadium Lower Half) Fall stadium occupancy with 30% design snow load, PASS PASS PASS PASS PASS PASS PASS PASS+ 1.5L(USC 1kPa) + 1.5L(LSC 4.8kPa) lower portion of the stadium occupied up to row 30, + 0.5[0.3S] minimal live load on the USC and full design live load on

the LSC. Arena not occupied.10 1.25D + 1.5L(Stadium) + 1.5L(Arena) Fall occupancy of the stadium and arena simultaneously PASS 1.14T PASS PASS PASS PASS PASS PASS

with 30% design snow load. 1.07C+ 0.5[0.3S]

NOTES:

D: Dead LoadL: Live LoadS: Snow LoadW: Wind Load

T: Tension side with numerical value equal to the factored stress/factored resistanceC: Compression side with numerical value equal to the factored stress/factored resistance

PASS: Factored stress is equal to or less than the factored resistance

Additional Load

Combinations

Analysis ResultsStadium Raker Beam

Operational Load

Combinations

Figure 6.1: Effect of Adjacent Building on Existing Snow Loads

10 1 h’

10h’

h

h’=h-CbCwSs/γ CbCwSs/γ: Height of snow

Existing Building

New Building

Snow

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