Upload
audilicious
View
178
Download
6
Tags:
Embed Size (px)
DESCRIPTION
Construction
Citation preview
5/19/2018 Building Superstructures
1/37
Lecture 1:BUIILDING SUPER-
STRUCTURES
5/19/2018 Building Superstructures
2/37
Contents:
Nature of Buildings
Building Superstructures
Solid Superstructures
Skeleton Superstructures
Surface Superstructures
Advantages of Frame Structures Classification of Frames
Materials for Building Frames
5/19/2018 Building Superstructures
3/37
Function of Buildings
As a shelter / envelope
To meet primary physical needs
Must be well-designed as well as constructed
Building technology and building techniques are interrelated
5/19/2018 Building Superstructures
4/37
Functions of building
Enclose spaceso that the satisfactory internal environment may
be created relative to the purpose and intended function of the
building
The space within the building must be suitable for the
activitiesto take place with it
Comfortable, safe, stable
Must be designed in terms of size and shape, and environmental
factors
5/19/2018 Building Superstructures
5/37
Building Superstructures
General Definition - portion of a building that is above theground.
In Malaysian constructionrefers to the building primaryelements that transfers the building load to the sub-structure(foundations)
Mainly as the main building structuralcomponent
5/19/2018 Building Superstructures
6/37
Building SuperstructuresDesigned to provide:
1 . better use of structuralmaterials (steel, brick, timber, concrete etc)
2. an easier methodof construction and erection/expansion
3. reduce cost
4. answerto a particularproblem (such as provision of a clear floor area for
a warehouse or a factory)
5. conform with the requirements of the designer (architect) in search of
visual appeal (aesthetic)
6. withstandthe forcesthat the building will carry i.e. does not move in any
manner under loads
5/19/2018 Building Superstructures
7/37
Types of Superstructures
3 basic types of superstructure:
i) Solid
ii) Skeleton
iii) Surface
5/19/2018 Building Superstructures
8/37
Solid Superstructures
Combines the load-carrying function with space enclosure
The loadsare transferredto and spread through the
walls/building frameto give a distributed load on the
substructure
The common types of solid structures:
i) cellular/box frame
ii) igloo
iii) cross wall
5/19/2018 Building Superstructures
9/37
Solid Superstructures
SolidSuperstructure
TypesBox Framed Structures Load-bearing WallsCellular Box Structure
Cross Wall Structure
Igloo
Load bearing wall
5/19/2018 Building Superstructures
10/37
Solid Superstructures
Cellular Box/Frame
the loads are transferred to the walls of the cells,
each wall being rigidly jointed to its neighbor
arrangementwhere both the internal and externalwalls are load-bearing and arranged to form a
cellular system
resulting structure is rigid and stable, suited
applications where large areas are not required or
alteration in layout are unlikely
5/19/2018 Building Superstructures
11/37
Solid Superstructures
Cross-walls
A generic method of building
constructionusing a series of division or
party walls which transfer the floor loads
through the building to foundation or
transfer slab level.
The walls are ususlly built at standardised
centres and spacing thus allowing other
elements aslo to be standardised
division or party walls
5/19/2018 Building Superstructures
12/37
Solid Superstructures
Load bearing walls A load-bearing wall(or bearing wall) is
a wall that bears a load resting upon it
Its weight is then transferred directly to the
foundation structure.
The materials most often used to constructload-bearing walls in large buildingsare concrete, block, or brick.
Depending on the type of building and thenumber of stories, load-bearing walls aregauged to the appropriate thickness to carrythe weight above them.
5/19/2018 Building Superstructures
13/37
Skeleton Structures
Comprise of a frameworkthrough which theloads are concentrated and transferred to the
supporting structure or substructure
The strength of the members of the
frameworkand their connectionsplays an
important part in the transmissionof the
applied loads
Common materials: timber, steel and
Reinforced concrete (RC)
5/19/2018 Building Superstructures
14/37
Skeleton Structures
Apex Frame
Rectangular Frame
Truss Frame
Portal Frame
Shed Frame
Grid Frame
Geodesic Frame
Suspension Frame
5/19/2018 Building Superstructures
15/37
Skeleton StructuresApex Frame
Framework of poles is jointedat or near one endto provide the
framework of a conical shape
5/19/2018 Building Superstructures
16/37
Apex Frame
5/19/2018 Building Superstructures
17/37
Skeleton StructuresRectangular Frame
A series of uprights and cross-members set up in mutually
perpendicularplanes
Provides the framework for support to the floors, walls and roofs
5/19/2018 Building Superstructures
18/37
Skeleton Structures
Truss Frame The truss frame a structure comprising one
or more triangular units
Constructed with straight members whose
ends are connected at joints referred to
as nodes.
External forces and reactions to those forcesare considered to act only at the nodes and
result in forces in the members which are
either tensile or compressive forces.
5/19/2018 Building Superstructures
19/37
Skeleton Structures
Portal Frame Portal frame construction is a method of building
and designing simple structures, primarily
using steelor steel-reinforced precast concrete
Similar to an arch, but consisting of two uprights
rigidly jointedby a horizontal, sloping or curvedthird
member
Each frame requires lateral support, usually in the
form of bracing
5/19/2018 Building Superstructures
20/37
Skeleton Structures
Shed Frame
Similar to portal
frame, but the third
member is in the
form of a roof truss
5/19/2018 Building Superstructures
21/37
Skeleton Structures
Grid Frame (Space Frames) Used for lightweight roof structure covering large
open floor areas
The frame comprises a series of triangular frames
set out in the form of a grid
The grid may be in the form of one, two or three
layers or of a space grid which comprises a six-
member frame joined to other similar frames
forming a strong rigid framework
5/19/2018 Building Superstructures
22/37
Skeleton Structures
Geodesic Frame Formed in the shape of a domeand comprising a
network of triangular frames in the form of spherical
triangles
i.e. portions of a sphere formed by the intersections
of great circles (great circles has a diameter equal to
that of the sphere it is drawn on)
The greater the number of triangles used in the
structure, the less the chance of collapse
5/19/2018 Building Superstructures
23/37
Skeleton Structures
Suspension Frame
Used in multi-storeyconstruction, it
comprises a central solid support structure
extending to the full height of the building
At the top of which a rigid horizontal
support structure is cantilevered out over
the plan area of the building
5/19/2018 Building Superstructures
24/37
Skeleton Structures
Functional Requirements The primary function of a skeleton frame is to carry all the loads imposed on the
building, without deforming excessively under load as a whole or in parts
Transfers all these loads to the building sub-structure (foundation)
To meet this function efficiently, it must have adequate design and construction
regarding:
i) strength and stability - appropriate materials & stiffness of joints
ii) fire resistance - for a period long enough for occupants to escape
5/19/2018 Building Superstructures
25/37
Surface Structures
Load carried by the roof and has thin skin
which is:
i. Sufficiently rigid to be self-supporting when
shaped and the shape provides additional
strength
ii. Sufficiently strong but flexible enough to support
load when stretched across a supporting
framework
5/19/2018 Building Superstructures
26/37
Surface Structures
Shell dome
Shell barrel vaultSuspension roofs and tents
Air-supported structure
5/19/2018 Building Superstructures
27/37
Surface Structures
Shell Dome
5/19/2018 Building Superstructures
28/37
Surface Structures
Barrel Vault
Both structures above use
their curved shape to obtainstrength e.g. principle of an
egg, when pressed by fingers
it will not break
5/19/2018 Building Superstructures
29/37
Barrel Vault
Surface Structures
5/19/2018 Building Superstructures
30/37
Surface Structures
Suspension Roofs & Tents
The membrane stretched oversome other skeleton framed
Form a structural component itself
5/19/2018 Building Superstructures
31/37
Air-Supported Structures
http://www.alibaba.com/catalog/11161717/Air_Supported_Structure.html5/19/2018 Building Superstructures
32/37
Advantages of Skeleton
Frame StructureAdvantages over solid & surface structures:
1. Save in floor space
2. Flexible in plan and building operations (because of the
absence of the load bearing walls at any level)
3. Reduction of dead weight
5/19/2018 Building Superstructures
33/37
Classification of Frames
The building frames may be classified according to the stiffness or
rigidity of the joints between members (especially in columns andbeams)
Non-rigid frame
The nature of the joints is such that the beams are assumed to
be simply supported and the joints are non-rigid
Rigidity in the frame structure as a whole is ensured by the
inclusions of some stiffening elements in the structure, often inthe form of triangulating members bracing (normally in steel
and pre-cast concrete frame)
5/19/2018 Building Superstructures
34/37
Classification of Frames
Semi-rigid frame
Where some or all jointsachieved some degree ofrigidity
Normally used in steel framedbuildings where connection areof both bolt and weld)
5/19/2018 Building Superstructures
35/37
Classification of Frames
3. Fully Rigid Frame
- Where all joints are rigid
- Normally in steel where joints are
welded & conc. frame where
members are cast monolithically
5/19/2018 Building Superstructures
36/37
Choice of Structural Materials for
Building Frames1. Concrete
- Strength varies according to the mix
- Strong in compression weak in tension
- Compressive strength1/16 of steel
-Tensile strength 1/10 of its compressive strength
- Stiffness is low compared to steel
2. Steel
-Very strong and stiff
- Strong both in compression and tension
- Relatively economical
- Non-combustible; but at 427 C482 C it will lost strength
5/19/2018 Building Superstructures
37/37
Factors that Influence the Choice of Building Frame
Structural Materials
i. Availability of materials and labours
ii. Cost
iii. Speed of erection
iv. Possibility of standardizing the size of structural members
v. Size and nature of site
vi. Fire resistance required