STRUCTURAL DESIGN OF A CAMMERCIAL BUILDING

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Location: GISENYI /RUBAVU

Plot No:567

Owner: Mr. Shona RUBERWA

Designed by:Eng .Pacifique B. MUMENYI

Date:Jan 2018

Approved by:

Page 1 of 29CONTENTSCONTENTS................................................................................................................................................ 10. INTRODUCTION .................................................................................................................................. 21. NOTATIONS.......................................................................................................................................... 32. ASSUMPTIONS..................................................................................................................................... 43. LAYOUT OF OVERALL PLAN [STRUCTURAL ARRANGEMENT] ............................................. 64. CALCULATION AND DESIGN OF SLABS: ...................................................................................... 76. CALCULATION AND DESIGN OF COLUMN ................................................................................ 197. CALCULATION AND DESIGN OF FOUNDATIONS ..................................................................... 238. CALCULATION AND DESIGN OF STAIRS.................................................................................... 26

Page 2 of 290. INTRODUCTIONThe aim of design is the achievement of an acceptable probability that structures being designed will

perform satisfactorily during their intended life. With an appropriate degree of safety, they should

sustain all the loads and deformations of normal construction and use and have adequate durability and

resistance to the effects of misuse and fire.

Once the building form and structural arrangement have been finalized the design problem consists of

the following:

1. Idealization of the structure into load bearing frames and elements for analysis and design2. Estimation of loads3. Analysis to determine the maximum moments, thrusts and shears for design4. Design of sections and reinforcement arrangements for slabs, beams, columns and walls using the

results from 35. Production of arrangement and detail drawings and bar schedules

Thisstructural design process has been carried out under use of BS8110 design code of practice.

Especially, computations have been made by use of BS 8110 based spreadsheets; publication produced

by the Reinforced Concrete Council (RCC) as part of its project 'Spreadsheets for concrete design to BS

8110 and EC2'.

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1. NOTATIONSThe symbolic notation used in this project is in accordance with the BS code of practice. Other symbols

not defined here, have been defined alongside the particular place where they have been applied.

A: cross section area

Asmin: minimum required reinforcement section

B : width of foundation footing, Beam

b: width reinforced concrete section

bf: width of flange in a beam

bw : width of web of a flanged a beam

C : cover

d : effective depth of tensile reinforcement

H : depth of foundation

fcu: characteristic yield strength of concreteat 28 days

fy: characteristic yield strength of steel

GK: dead load

h: overall depth of a concrete section

hf: thickness of flange in a T-beam

L : span length

lx : short-span length

ly: long-span length

M : bending moment

p: perimeter

qadm: bearing pressure

Qk: imposed load

S: spacing of shear reinforcement

V: shear force in concrete section

Øt: shear reinforcement diameter

Ø: reinforcementdiameter

B.S: British standard

C.P: Code of Practice

RC: Reinforced concrete

m.f: modification factor

`

Page 4 of 292. ASSUMPTIONSDesign standards used

Design standard used to determine section of steel bars of different structural elements of concerned

building are BS 8110

UnitiesVolumetric load: kN/m3

Surface load: kN/m2

Linear load: kN/m

Point load: kN

Dead loads

Roof structure: 1.5kN/m2

Reinforced concrete: 25kN/m3

Wall Finishes: 22kN/m2

Masonry in burnt bricks: 20kN/m3

Coating in cement mortar: 20kN/m3

Plinth 22kNm2

Masonry in cement blocks: 13.5kN/m3

Slab finishes 2kN/m2

Imposed load or live load

Residential house building: 1.5kN/m2

Cover conditions

Slabs, beams and columns [mild condition]: 30mm

Foundation pads [moderate condition]: 40mm

Soil characteristics

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Sandy-gravel subsoil of unit weight: 18kN/m3

Allowable bearing pressure: 240kN/ m2

Mix proportions [BS 5328-2]

Mix ratio: 350 kg/ m3

Elasticity limit for construction materials

Strength of reinforcement:

Hot rolled mild steel: 250 N/mm2

High yield steel : 460 N/mm2

Concrete ƒck: 30N/mm2

Partial safety magnification factors

For dead load: 1.4

For live load: 1.6

Basic span-effective depth ration: 26

Page 6 of 293. LAYOUT OF OVERALL PLAN [STRUCTURAL ARRANGEMENT]Foundations, columns, beams, slabs and stair

STRUCTURAL PLAN

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4. CALCULATION AND DESIGN OF SLABS:Critical slabsSLAB, CC, GG -33,66

Layout

Analysis (SLAB BC, 22,44)

Estimating the modification factor to be of the order of 1.3;

ℎ = ℎ26 × ( . )= × . = 109.5

Lx=5.2 m

Ly= 4 m

For our slab; ly / lx = 1< 2 so we have a two-ways slab.

Try effective depth d=109.5 mm.

Taking 5mm as half the diameter of the reinforcing bar

Overall depth of slab h= 109.5+5+30= 144.5≈150 mm

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Self weight of slab= 0.15×25= 3.75kN/m2

Total dead load= finishing + self weight = 2+ 3.75 = 5.75 kN/m2

Imposed load= 1.5kN/m2 forresidential building

Ultimate design load=1.4×5.75 +1.6×1.5=10.45 kN/m2

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5. CALCULATION AND DESIGN OF A BEAMS:Critical beamsI. Beam Type 4-4

Layout

Calculation and design

Type: T beam

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Transverse Section of beam

Breadth of the web, bw = 250 mm

L1=4.214m

L2=2.795m

L3=3.217m

L4=1.981m

L5=3.211m

L6=3.611

Nominal diameter 8 mm links and 16 mm for main bars

Preliminary analysis

h≥ = = 280.9 let take 450mm

bw≥0.6*h = 0.6*280.9=168.54mm let take 250mm

The effective breadth bf of flanged beams is given in BS8110:

1. T-beams-web width bw+lz/5 or the actual flange width if less

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2. L-beams-web width BW+lz/10 or the actual flange width if less

Where lz is the distance between points of zero moment in the beam. In continuous beams lz may betaken as 0.7 times the effective span.

A general bf for this continuous beam has been taken as:

= + 0.7 × 5 = 250 + 0.7 × 42145 = 839.9The area of the T-beam is given by:

A=[bw×(h-hf)]+(bf×hf) =(0.25*0.3)+(0.839*0.15)=0.20085 m2

Load Surface of the span 1-2 of the beam S=7.524m2

Load Surface of the span 2-3of the beam S=3.365m2

Load Surface of the span 3-4of the beam S=4.55m2

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Computation

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Page 19 of 296. CALCULATION AND DESIGN OF COLUMNCritical columnsColumn EE-33Layout

Column load-take down design

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Computation

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7. CALCULATION AND DESIGN OF FOUNDATIONSCritical foundationsFoundation on column C-3

Layout

Bearing pressure =240kN/m2

Use nominal cover=40mm (cover against blinding)

H=350mm

Pressure from foundation: 25kN/m3x0.35m =8.75kN/m2

Pad area required = design load/effective bearing pressure

Effective bearing pressure=240kN/m2-8.75kN/m2≈231.25kN/m2

N= P= 575kN

Pad area required= 575kN/231.25kN/m2= 2.41m2

Thus B=L≈1.20m

Dead load: 575kN

Imposed load: 0.8Kn

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Computation

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Page 26 of 298. CALCULATION AND DESIGN OF STAIRSCritical stairsThe of practice C P 110 give the standart using in the design of stairs

Input Privet building Pubrique building

Rise R Less than 220mm Less than 190mm

Riser G Greater than 220mm Greater than 230mm

Slope S Less 42 degree Less 38 degree

Number of rises/ span - Less than 16

General design : 700mm>G+2*R>550mm

Layout

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