prev

next

out of 42

View

64Download

27

Embed Size (px)

DESCRIPTION

reference report on Highrise Building

PG/DIP Structural Engineering Page-1

Contents

1. Introduction

2. Preliminary selection of structural elements

3. Wind Analysis

4. Earthquake Analysis

5. Element Design

6. Reference

PG/DIP Structural Engineering Page-2

Design of a Forty Story Building for ABC bank head quarts

1.0 Introduction

It is decided to design a forty storied building for the use of ABC bank at Colombo 7. Whole

building is to be used as Bank head quarts and rent some space to be used as office.

Designed will be done as a part of the course work of Pg Dip /MEng (Structural Design )

program.

Key features of the building

1- 40 storied building

2- 8 floors to be used as car park

3- Lift system is designed as Hard Zoning

4- Building length 48m

5- Building width 36m

6- Super structure will be reinforced concrete and sub structure will be pile foundation.

Following designs will be considered in this Report.

Decide grid arrangement and building services

Selecting the arrangement of strong elements

Selection of suitable loads

Selection of dynamic parameters

Determination of wind loads and induced acceleration

Determination of earth quake loads

Develop computer model and determination of member forces

Design of slab beam wall column and pile foundation

PG/DIP Structural Engineering Page-3

1.1 Calculation of basic parameters of the building

Let Column spacing in longest direction = 8m

Therefore no of columns 48/8+1 = 7

Let column spacing in shortest direction = 6m

Therefore no of columns 36/6+1 = 7

Let beam height (hb) 6000/14+25 = 450mm

Slab Thickness (Ts) 6000/44+25 = 160 mm

Let space for services c = 300 mm

Let head clearance h = 2.5 m

Total Floor height h+c+Ts+hb = 2.5+.3+.45

H = 3.25m

Height of the Building 3.25x40 = 130m

Height/Width Ratio 130/36 = 3.6

One Floor Area 36x48 = 1728 m2

Lift Core Area 24x16 = 384 m2

Usable Area = 1344 m2

PG/DIP Structural Engineering Page-4

7

6

5

4

3

2

16.00 m

6.00 m

6.00 m

6.00 m

6.00 m

6.00 m

36.00 m

48.00 m

8.00 m

A B C D E F G8.00 m 8.00 m 8.00 m 8.00 m 8.00 m

Fig 1 Building Layout

1.2 Calculation of Number of Lifts

Let population density = 10 m2

Number of people per floor 1344/10 = 134.4 per floor

Let = 135 persons per floor

PG/DIP Structural Engineering Page-5

8th Floor (Car park)

10th Floor

20th Floor

30th Floor

40th Floor

Expre

ss R

un

Expre

ss R

un

Hard zoning arrangement will be used as follows.

Fig 2 Lift Arrangement

1.2.1 Ground floor level to 19th floor level

Population calculation Ground floor to 19th floor = 135 x 12

= 1620 persons

Let consider serving for 5 minute peak capacity.

Peak capacity is assumed as 14% of the total population .

Hence, population handled in 5 minute period = 1620x14/100

= 226.8persons

Let 227 persons

Let select 24 capacity lift, Average interval = 28 sec (Table 25 7.1)

PG/DIP Structural Engineering Page-6

Let select 4m/s speed lift system, hence round trip time = 165 s

Hence, number of lifts required Round Trip Time

Average Interval

= 165 / 28

= 5.89

Hence, 6 lift required between ground floor level and 19th floor level.

1.2.2 20th floor level to 29th floor level

Population calculation 20th floor to 29th floor = 135 x 10

= 1350 persons

Let consider serving for 5 minute peak capacity.

Peak capacity is assumed as 14% of the total population

Hence, population handled in 5 minute period = 1350 x 14/100

= 189 persons

Let select 24 capacity lift ,Average interval = 32 sec (Table 25 7.1)

Let select 4m/s speed lift system, for 18 floors hence round trip time = 160 s

Lift will travel express 6 ms-1 from 8th floor level to 19th floor level and serve 20th floor to 29th

floor.

Hence, total distance traveled = 12 x 3.25 x 2

= 78 m

Hence, time taken = 78 / 6

= 13 s

Total round trip time = 160 + 13 s

= 173 s

Hence, number of lifts required = Round Trip Time

PG/DIP Structural Engineering Page-7

Average Interval

= 173 / 32

= 5.4

Say, 5 lifts

Hence, 5 lift cars to serve between 20th floor level and 29th floor level.

1.2.3 30th floor level to 39th floor level

Population calculation 30th floor to 39th floor = 135 x 10

= 1350 persons

Let consider serving for 5 minute peak capacity.

Peak capacity is assumed as 14% of the total population

Hence, population handled in 5 minute period = 1350 x 14/100

= 189 persons

Let select 24 capacity lift ,Average interval = 32 sec (Table 25 7.1)

Let select 4m/s speed lift system, hence round trip time = 160 s

Lift will travel express 6 ms-1 from 8th floor level to 29th floor level and serve 30th floor to 39th

floor.

Hence, total distance traveled = 22 x 3.25 x 2

= 143 m

Hence, time taken = 143 / 6

= 23.8 s

Total round trip time = 160 + 24 s

= 184 s

Hence, number of lifts required = Round Trip Time

PG/DIP Structural Engineering Page-8

Average Interval

= 184 / 32

= 5.7

Say 6 lifts

Hence, 6 lift cars can be used to serve between 30th floor level and 39th floor level.

Summary of the lift arrangement as follows.

Location No of lifts

Ground floor level to 19th floor level 6

20th floor level to 29th floor level 5

30th floor level to 39th floor level 6

Total 17

Table 1 Required lift at each zone

1.2.4 Lift cabin arrangement

From Table 25.3

Cabin size of the 24 passenger lift = 2100 x 1650

Shaft size = 2550 x 2400

1.2.5 Stair case arrangement

Width = 2m

Length = 3.35m

Landing length = 4m

Landing width = 1.5m

Required opening area = (3.35+1.5)x 4 m2

= 19.4m2

PG/DIP Structural Engineering Page-9

1.2.6 Wash rooms arrangement

There will be two washrooms for men and women, 7.5m x7.5m each

1.2.7 Service Core Arrangement

Length = 24m

Width = 16m

Fig 3 Service Core Arrangements

men

wash room

ladies

wash room

7

6

5

4

3

2

16.00 m

6.00 m

6.00 m

6.00 m

6.00 m

6.00 m

36.00 m

48.00 m

8.00 m

A B C D E F G8.00 m 8.00 m 8.00 m 8.00 m 8.00 m

PG/DIP Structural Engineering Page-10

men

wash room

ladies

wash room

7

6

5

4

3

2

16.00 m

6.00 m

6.00 m

6.00 m

6.00 m

6.00 m

36.00 m

48.00 m

8.00 m

A B C D E F G8.00 m 8.00 m 8.00 m 8.00 m 8.00 m

1.2.8 Shear wall arrangement

Lateral loads are to be resisted by a shear wall arrangement.

Assumed Shear wall thicknesses are as follows.

Zone Selected Shear wall

thickness / (mm)

Ground to 9th floor level 300

10th floor to 19th floor level 300

20th floor to 29th floor level 300

30th floor to 39th floor level 300

Table 2 Shear wall Thickness

Fig 4

Shear wall

arrangement

PG/DIP Structural Engineering Page-11

2.0 Preliminary selection of structural elements.

Slab Thickness

Selected slab thickness = 175 mm

Cover = 25 mm

Diameter of the reinforcement = 10 mm

Hence, effective depth = 175 - 25 10/2

= 145 mm

Span / Effective depth = 6000 / 145

= 41.4

Basic span / Effective depth = 26 ( T 3.9 BS8110)

Let Assume a modification factor of 1.6

Modified span / Effective depth = 26 x 1.6

= 41.6

Hence, 175 mm slab thickness is capable of meeting the deflection criteria satisfactorily.

2.1 Selection of Beam Dimensions

Selected beam depth = 600 mm

Hence, effective depth = 550 mm

Span / Effective depth = 8000 / 550

= 14.55

PG/DIP Structural Engineering Page-12

2.2 Determination of Column Dimensions

Initial column size can be selected with trial approximate loads

Assume column carries load from 8 x 6 panel area of the building. Trial size of column will be

selected according to axial load capacity

2.2.1 Dead loads calculation

Slab self-weight = 8 x 6 x 0.175 x 24

= 201.6 kN

Assuming Finishes of 0.75 kN / m2 = 0.75 x 8 x 6

= 36kN

Assuming partition of 1.0 kN / m2 = 1.0 x 8 x 6 (BS 6399 5.1.4)

= 48 kN

Assuming services of 1.0 kN / m2 = 1.0 x 8 x 6

= 48 kN

Beams Weight = (8 + 6) x 0.4 x 0.6 x 24

= 80.64 kN

Live load on slab of2.5 kN / m2 = 2.5 x 8 x 6 (BS 6399)

= 120 kN

Calculation of desig