DESIGN ANALYSIS OF LOW COST MULTI STORED

The major current methods of construction systems considered here are namely, structural block walls, mortar less block walls, prefabricated roofing components like precast RC planks, pr

DESIGN AND ANALYSIS OF LOW COST MULTI STORED

BUILDING USING STAAD PRO

Abstract

This paper aims to point out the various aspects of prefabricated building methodologies for low cost school building by highlighting the different prefabrication techniques, and the economical advantages achieved by its adoption In a building the foundation, walls, doors and windows, floors and roofs are the most important components, which can be analyzed individually based on the needs thus, improving the speed of construction and reducing the construction cost The major current methods of construction systems considered here are namely, structural block walls, mortar less block walls, prefabricated roofing components like precast RC planks, precast hollow concrete panels, precast concrete/Ferro cement panels are considered.low cost school building design using Staad pro vi8

Keywords: Prefabrication; Precast RCC „kular‟, precast joist, Ferro cement

products ,Staad pro vi8

Introduction of low cost Multi Storedbuilding,Planning and designing of school building designwith transfer girder and floating columns as perarchitect requirement using Staad Pro Vi8 software

CASE 2

Analyzing the structural frame with floatingpiersbased on sequence of constructionfordesign loads (DL, LL) and structure as a whole

for WL and SL

CASE 1

Analyzing the structural frame with

floating piers as a whole for design loads

Introduction

Affordable housing is a term used to describe dwelling units whose total housing cost are deemed “Affordable” to a group of people within a specified income range In India, the technology to be adopted for housing components should be such that the production and erection technology be adjusted to suite the level of skills and handling facilities available under metropolitan, urban and rural conditions.

Logical approach for optimizing housing solutions: There should be a logical

approach for providing appropriate technology based on the availability of options, considering its technical and economical analysis

1 There should be optimal space in the design considering efficiency of space,

minimum circulation space

2 Economy should be considered in design of individual buildings, layouts,

clusters etc

3 While preparing the specifications it should be kept in mind that, cost

effective construction systems are adopted

4 Energy efficiency has gained considerable importance due to energy crisis

especially in developing countries Orientation, built–form, openings & materials play a vital role besides landscaping / outdoor environment

5 To develop an effective mechanism for providing appropriate technology

based shelter particularly to the vulnerable group and economically weaker section.(R.K.Garg, 2008)

Prefabrication as applied to `Low Cost School Building(P.K.Adlakha and H.C.Puri, 2002) Advantages of prefabrication are:

1 In prefabricated construction, as the components are readymade,

self-supporting, shuttering and scaffolding is eliminated with a saving in shuttering cost

ACSGE-2009, Oct 25-27, BITS Pilani, India

2 In conventional methods, the shuttering gets damaged due to its repetitive use

because of frequent cutting, nailing etc On the other hand, the mould for the precast components can be used for large number of repetitions thereby reducing the cost of the mould per unit

3 In prefabricated housing system, time is saved by the use of precast elements

which are casted off-site during the course of foundations being laid The finishes and services can be done below the slab immediately While in the conventional in-situ RCC slabs, due to props and shuttering, the work cannot be done, till they are removed Thus, saving of time attributes to saving of money

4 In precast construction, similar types of components are produced repeatedly,

resulting in increased productivity and economy in cost too

5 Since there is repeated production of similar types of components in precast

construction, therefore, it results in faster execution, more productivity and economy

6 In prefabricated construction, the work at site is reduced to minimum,

thereby, enhancing the quality of work, reliability and cleanliness

7 The execution is much faster than the conventional methods, thereby,

reducing the time period of construction which can be beneficial in early returns

of the investment

Concept of prefabrication / partial prefabrication has been adopted for speedier construction, better quality components & saving in material quantities & costs Some of these

Construction techniques &Materials for walls, roof & floor slab, doors & windows are as follows:

In Walls:-

In the construction of walls, rammed earth, normal bricks, soil cement blocks, hollow clay blocks, dense concrete blocks, small, medium and room size panels etc of different sizes are used However, bricks continue to be the backbone of the building industry In actual construction, the number of the bricks or blocks that are broken into different sizes to fit into position at site is very large which results in wastage of material poor quality Increasing the size of wall blocks will prove economical due to greater speed and less mortar consumption, which can be achieved by producing low density bigger size wall blocks using industrial wastes like blast furnace slag and fly ash Several prefabrication techniques have been developed and executed for walls but these medium and large panel techniques have not proved economical for low rise buildings as compared to traditional brick work (P.K.Adlakha and H.C.Puri, 2002)

i Non erodible mud plaster:

The plaster over mud walls gets eroded during rains, which necessitates costly annual repairs This can be made non erodible by the use of bitumen cutback emulsion containing mixture of hot bitumen and kerosene oil The mixture is pugged along with mud mortar and wheat/ rice straw This mortar is applied on mud wall surface in thickness of 12 mm One or two coats of mud cow dung

slurry with cutback are applied after the plaster is dry The maintenance cost is low due to enhanced durability of mud walls.(R.K.Garg, 2008)

Fig 1 Mud Plastered House

ii Fly –Ash sand lime bricks:

By mixing of lime and fly ash in the presence of moisture, fly ash sand lime bricks are made Fly Ash reacts with lime at ordinary temperature and forms a compound possessing cementitious properties After reactions between lime and fly ash, calcium silicate hydrates are ACSGE-2009, Oct 25-27, BITS Pilani, India

Produced which are responsible for the high strength of the compound Bricks made by mixing lime and fly ash are therefore, chemically bonded bricks The bricks are manufactured with the help of hydraulic press and are dried in the autoclave These bricks have various advantages over the clay bricks, It possesses adequate crushing strength, uniform shape, smooth finish and does not require plastering and also are lighter in weight than ordinary clay bricks (R.K.Garg, 2008)

iii Solid concrete and stone blocks:

This technique is suitable in areas where stones and aggregates for the blocks are available locally at cheaper rates Innovative techniques of solid blocks with both lean concrete and stones have been developed for walls The gang-mould is developed for semi-mechanized faster production of the blocks In the manual process, single block moulds are used wherein the concrete is compacted with help of a plate vibrator With the use of a portable power screw driven egg laying type machine, solid concrete blocks are made with higher productivity at low cost Six blocks of 30 x 20 x 5 cm size are cast in single operation with an output of 120-150/hr (R.K.Garg, 2008)

In Floor and Roof: Structural floors/roofs account for substantial cost of a

building in normal situation Therefore, any savings achieved in floor/roof considerably reduce the cost of building Traditional Cast-in-situ concrete roof involve the use of temporary Shuttering which adds to the cost of construction and time Use of standardized and optimized roofing components where shuttering is avoided prove to be economical, fast and better in quality Some of the prefabricated roofing/flooring components found suitable in many low-cost housing projects are:

i Precast RC Planks

ii Prefabricated Brick Panels

iii Precast RB Curved Panels

iv Precast RC Channel Roofing

v Precast Hollow Slabs

vi Precast Concrete Panels

vii L Panel Roofing

viii Trapezon Panel Roofing

ix Un reinforced Pyramidal Brick Roof

i Precast RC plank roofing system:

This system consists of precast RC planks supported over partially precast joist.

RC planks are made with thickness partly varying between 3 cm and 6 cm There are haunches in the plank which are tapered When the plank is put in between the joists, the space above 3 cm thickness is filled with in-situ concrete

to get tee-beam effect of the joists A 3 cm wide tapered concrete filling is also provided for strengthening the haunch portion during handling and erection The

planks have 3 numbers 6 mm dia MS main reinforcement and 6 mm dia @ 20

cm centre to centre cross bars The planks are made in module width of 30 cm with maximum length of 150 cm and the maximum weight of the dry panel is 50

kg (Figure 2) Precast joist is rectangular in shape, 15 cm wide and the precast portion is 15 cm deep (Figure 2) The above portion is casted while laying in- situ concrete over planks The stirrups remain projected out of the precast joist Thus, the total depth of the joist becomes 21 cm The joist is designed as composite Tee-beam with 6 cm thick flange comprising of 3 cm precast and 3

cm in-situ concrete (Figure 3) This section of the joist can be adopted up to a span of 400 cm For longer spans, the depth of the joist should be more and lifting would require simple chain pulley block The completely finished slab can be used as intermediate floor for living also In residential buildings, balcony projections can be provided along the partially precast joists, designed with an overhang carrying super imposed loads for balcony as specified in IS: 875-1964,

in addition to the self load and the load due to balcony railings The main reinforcement of the overhang provided at the top in the in-situ concrete attains sufficient strength The savings achieved in practical implementations compared with conventional RCC slab is about 25%.(P.K.Adlakha and H.C.Puri, 2002) ACSGE-2009, Oct 25-27, BITS Pilani, India

Fig 2 Precast R.C Planks Fig

Fig 3 R.C Planks laid over partially precast joists

3 R.C Planks laid over partially precast joists

ii Prefabricated brick panel roofing system:

The prefabricated brick panel roofing system consists of:

(a)Prefab brick panel Brick panel is made of first class bricks reinforced

with two MS bars of 6 mm dia and joints filled with either 1:3 cement sand mortar or M-15 concrete Panels can be made in any size but generally width is 53 cm and the length between 90 cm to120 cm, depending upon the requirement The gap between the two panels is about 2 cms and can be increased to 5 cms depending upon the need A panel of 90 cm length requires 16 bricks and a panel of 120 cm requires

19 bricks (Figure 4) (P.K.Adlakha and H.C.Puri, 2002)

(b)Fig 4 Brick Panel (b) Partially precast joist It is a rectangular shaped

joist 13 cm wide and 10 cm to 12.5 cm deep with stirrups projecting out

so that the overall depth of joist with in-situ concrete becomes 21 cm to 23.5 cm, it is designed as composite Tee-beam with 3.5 cm thick flange (Figures 5 and 6 ) (P.K.Adlakha and H.C.Puri, 2002)

Fig 6 Precast R C Plank and Joist System Fig

5 Details of Precast Joist Structural design

The prefab brick panel for roof as well as for floor of residential buildings has two numbers 6 mm dia MS bars as reinforcement up to a span of 120 cms The partially precast RC joist, is designed as simply supported Tee-beam with 3.5cm thick flange The reinforcement in joist is provided as per design requirements depending upon the spacing and span of the joist ACSGE-2009, Oct 25-27, BITS Pilani, India

An overall economy of 25% has been achieved in actual practice compared to cast-in-situ RCC slab (P.K.Adlakha and H.C.Puri, 2002)

iii Precast curved brick arch panel roofing

This roofing is same as RB panel roofing except that the panels do not have any reinforcement A panel while casting is given a rise in the centre and thus an arching action is created An overall economy of 30% has been achieved in single storeyed building and 20% in two or three storeyed buildings (Figure 7) (P.K.Adlakha and H.C.Puri, 2002)

Fig 7 Pre Fab Brick Arch Panel

iv Precast RC channel roofing

Precast channels are trough shaped with the outer sides corrugated and grooved

at the ends to provide shear key action and to transfer moments between adjacent units Nominal width of units is 300 mm or 600 mm with overall depths of 130 mm to 200 mm (Figure 8) The lengths of the units are adjusted to suit the span The flange thickness is 30 mm to 35 mm Where balcony is provided, the units are projected out as cantilever by providing necessary reinforcement for cantilever moment A saving of 14% has been achieved in actual implementation in various projects (P.K.Adlakha and H.C.Puri, 2002)

Fig 8 RC Channel Unit System

v Precast hollow slabs roofing

Precast hollow slabs are panels in which voids are created by earthen kulars without decreasing the stiffness or strength These hollow slabs are lighter than solid slabs and thus save the cost of concrete, steel and the cost of walling and foundations too due to less weight The width of a panel is 300 mm and depth may vary from 100 mm to 150 mm as per the span, the length of the panel being adjusted to suit the span The outer sides are corrugated to provide transfer of shear between adjacent units The‟kulars„ are placed inverted so as to create a hollow during precasting (Figure 9) Extra reinforcement is provided at top also

to take care of handling stresses during lifting and placement There is saving of about 30% in cost of concrete and an overall saving of about 23%.(P.K.Adlakha and H.C.Puri, 2002)

Fig.9 Hollow Slabs Roofing System

vi L- Pan roofing

The pre-cast full span RC L-panel is of section „L‟ The L- panels are supported

on parallel gable walls and are used for sloped roof of a building The RC units can be cast ACSGE-2009, Oct 25-27, BITS Pilani, India

with simple timber/ steel moulds and are easy for manual handling with simple lifting and hoisting gadgets L-Panel roofing is quite lighter in weight, economic

in construction and sound in performance and durability In addition to roof, the L-panels can be used for making loft, cooking platforms, parapets and many other minor elements of buildings and structures The techniques has been used widely in many mass housing programme in the country (figure:10) (R.K.Garg,

2008) Fig.10 L Pan Roofing System

vii Trapezonpan roofing flooring

Typical precast RC trapezonpanel has trapezium section in orthogonal directions The components are sound and can be manually handled with ease These components are placed in position to form roof/floor and haunch filling is done with in-situ concrete to make a monolithic surface Trapezo-panels can be produced in stacks one above the other and have advantage in production, stacking and supply These units are used for floors/ roofs with / without deck concrete.(figure:11) (R.K.Garg, 2008)

Fig.11 Trapezonpan Roofing System

viii Un-reinforced pyramidal brick roof

Un-reinforced pyramidal brick roof construction system is suitable for low cost houses in cyclone affected and other coastal areas Corrosion of reinforcement was found to be the major cause of failure of RCC structure in coastal areas and

a pyramidal roof with brick and cement concrete without reinforcement was therefore developed The roof is provided with peripheral RCC Ring beam The beam is supported on eight brick columns or walls and is cast as integral part of the pyramidal roof using suitable shuttering The roof can be of different sizes and shapes (Figure 12) (R.K.Garg, 2008)

Fig.12 Un Reinforced Pyramidal Brick Roof Seismic strengthening arrangements of precast roofing systems

IS-4326; 1993 has given recommendations regarding strengthening measures for precast roofing techniques The code recommends that for building category

A, B and C based on seismic co-efficient, a tie beam is to be provided all round the floor or roof to bind together all the precast components to make it a diaphragm The beams shall be to the full width of supporting wall less the bearing of precast components The depth of the beam shall be equal to the depth of the precast components plus the thickness of structural deck concrete, whenever used over the components Tie beams shall be provided on all longitudinal and cross walls In category D, structural deck concrete of 35 mm thickness reinforced with 6 mm dia bars, 150 mm both ways and anchored into tie beams shall be provided For economy, the deck concrete itself can serve as floor finish (P.K.Adlakha and H.C.Puri, 2002)

Other uses of prefabrication

The use of prefabrication for other materials can be made like lintels, sun shades, cupboard shelves, kitchen working slab and shelves, precast Ferro cement tanks, precast staircase steps, precast ACSGE-2009, Oct 25-27, BITS Pilani, India 7 Ferro cement drains (P.K.Adlakha and H.C.Puri, 2002)

(a) Thin precast RCC lintel

Normally lintels are designed on the assumption that the load from a triangular portion of the masonry above, acts on the lintel Bending moment will be WL/8 where W is the load on the lintel and L is the span assumed for the design purpose By this method, a thickness of 15 cm is required Thin precast RCC lintels are designed taking into account the composite action of the lintel with the brick work Design chart prepared for thin precast RCC lintels in the brick walls of normal residential building is applicable only when the load on the lintel is uniformly distributed The brick work over the lintel is done in a mortar not leaner than 1:6 The thickness of the lintel is kept equal to the thickness of brick itself having a bearing of 230 mm on either supports Use of precast lintels speeds up the construction of walls besides eliminating shuttering and centering Adoption of thin lintels results in upto 50% saving in materials and overall cost

of lintels (P.K.Adlakha and H.C.Puri, 2002)

(b) Doors and windows

Innumerable types and sizes of doors and windows used in single and similar buildings This involves the use of additional skilled labour on site and off site and also wastage of expensive materials like timber, glass etc Economy can be achieved by: (i) Standardizing and optimizing dimensions; (ii) Evolving restricted number of doors and window sizes; and (iii) Use of precast door and window frames.

(Fig 13) Fig.13Frame Less Door

Materials used:- (BMTPC- Building Materials & Technology Promotion Council, Govt of India)

By and large, conventional building materials like burnt bricks, steel and cement

are higher in cost, utilize large amount of non-renewable natural resources like

energy, minerals, top soil, forest cover,etc, The continued use of such

conventional materials has adverse impact on economy and environment.

Environment friendly materials and technologies with cost effectiveness are,

therefore, required to be adopted for sustainable constructions which must fulfill

some or more of the following criterion :-

Not endanger bio-reserves and be non-polluting Be self-sustaining and promote

self-reliance

Recycle polluting waste into usable materials Utilize locally available

materials Utilize local, skills, manpower and managing systems Benefit local

economy by being income generating Utilize renewable energy sources Be

accessible to people Be low in monetary cost

1 Bamboo Mat Board

Raw material source Bamboo grass(plant), Species

Materials for production Bamboo, polymeric resin, chlorinated

hydrocarbons and boron and cashew nut shell liquid

membrane,falseceiling, door/window frames

LOADS CONSIDERED

3.1 DEAD LOADS:

All permanent constructions of the structure form the dead loads The dead load comprises of

the weights of walls, partitions floor finishes, false ceilings, false floors and the other

permanent constructions in the buildings The dead load loads may be calculated from the

dimensions of various members and their unit weights the unit weights of plain concrete and

reinforced concrete made with sand and gravel or crushed natural stone aggregate may be

taken as 24 kN/m” and 25 kN/m” respectively

3.2 IMPOSED LOADS:

Imposed load is produced by the intended use or occupancy of a building including the

weight of movable partitions, distributed and concentrated loads, load due to impact and

vibration and dust loads Imposed loads do not include loads due to wind, seismic activity,

snow, and loads imposed due to temperature changes to which the structure will be subjected

to, creep and shrinkage of the structure, the differential settlements to which the structure mayundergo.

3.3 WIND LOAD:

Wind is air in motion relative to the surface of the earth The primary cause of wind is traced

to earth’s rotation and differences in terrestrial radiation The radiation effects are primarilyresponsible for convection either upwards or downwards The wind generally blowshorizontal to the ground at high wind speeds Since vertical components of atmosphericmotion are relatively small, the term ‘wind’ denotes almost exclusively the horizontal wind,vertical winds are always identified as such The wind speeds are assessed with the aid ofanemometers or anemographs which are installed at meteorological observatories at heightsgenerally varying from 10 to 30 metres above ground

3.4 Design Wind Speed (V,)

The basic wind speed (V,) for any site shall be obtained from and shall be modified to includethe following effects to get design wind velocity at any height (V,) for the chosen structure:a)Risk level;

b) Terrain roughness, height and size of structure; and

c) Local topography.

It can be mathematically expressed as follows:

Where:

V = Vb * kl * k2* k3

Vb = design wind speed at any height z in

m/s; kl = probability factor (risk coefficient)

k = terrain, height and structure size factor

and ks = topography factor

3.5 Risk Coefficient (kI Factor) gives basic wind speeds for terrain Category 2 as applicable

at10 m above ground level based on 50 years mean return period In the design of allbuildings and structures, a regional basic wind speed having a mean return period of 50 yearsshall be used

3.6 Terrain, Height and Structure Size Factor (k2, Factor)

Terrain - Selection of terrain categories shall be made with due regard to the effect ofobstructions which constitute the ground surface roughness The terrain category used in thedesign of a structure may vary depending on the direction of wind under consideration.Wherever sufficient meteorological information is available about the nature of winddirection, the orientation of any building or structure may be suitably planned

3.7 Topography (k3 Factor) - The basic wind speed Vb takes account of the general level of

siteabove sea level This does not allow for local topographic features such as hills, valleys,cliffs, escarpments, or ridges which can significantly affect wind speed in their vicinity Theeffect of topography is to accelerate wind near the summits of hills or crests of cliffs,escarpments or ridges and decelerate the wind in valleys or near the foot of cliff, steepescarpments, or ridges

3.8 WIND PRESSURES AND FORCES ON BUILDINGS/STRUCTURES:

The wind load on a building shall be calculated for:

a)The building as a whole,

b) Individual structural elements as roofs and walls, and

c) Individual cladding units including glazing and their fixings

Pressure Coefficients - The pressure coefficients are always given for a particular surface

orpart of the surface of a building The wind load acting normal to a surface is obtained bymultiplying the area of that surface or its appropriate portion by the pressure coefficient (C,)and the design wind pressure at the height of the surface from the ground The average values

of these pressure coefficients for some building shapes Average values of pressurecoefficients are given for critical wind directions in one or more quadrants In order todetermine the maximum wind load on the building, the total load should be calculated foreach of the critical directions shown from all quadrants Where considerable variation ofpressure occurs over a surface, it has been subdivided and mean pressure coefficients givenfor each of its several parts

Then the wind load, F, acting in a direction normal to the individual structural element orCladding unit is:

F= (Cpe – Cpi) A Pd

Where,

Cpe = external pressure coefficient,

Cpi = internal pressure- coefficient,

A = surface area of structural or cladding unit, and

Pd = design wind pressure element

3.9 SEISMIC LOAD:

Design Lateral Force

The design lateral force shall first be computed for the building as a whole This design lateralforce shall then be distributed to the various floor levels The overall design seismic forcethus obtained at each floor level shall then be distributed to individual lateral load resistingelements depending on the floor diaphragm action

3.10 Design Seismic Base Shear

The total design lateral force or design seismic base shear (Vb) along any principal directionshall be determined by the following expression:

Vb = Ah W

Ah = horizontal acceleration spectrum

W = seismic weight of all the floors

3.11 Fundamental Natural Period

The approximate fundamental natural period of vibration (T,), in seconds, of a resisting frame building without brick in the panels may be estimated by the empiricalexpression:

moment-Ta=0.075 h0.75 for RC frame building

Ta=0.085 h0.75 for steel frame building

Where,

h = Height of building, in m This excludes the basement storeys, where basement walls areconnected with the ground floor deck or fitted between the building columns But it includesthe basement storeys, when they are not so connected The approximate fundamental naturalperiod of vibration (T,), in seconds, of all other buildings, including moment-resisting framebuildings with brick lintel panels, may be estimated by the empirical Expression:

3.12 Distribution of Design Force

Vertical Distribution of Base Shear to Different Floor Level

The design base shear (V) shall be distributed along the height of the building as per thefollowing expression:

Qi=Design lateral force at floor

i, Wi=Seismic weight of floor i,

hi=Height of floor i measured from base, and

n=Number of storeys in the building is the number of levels at which the masses are located Distribution of Horizontal Design Lateral Force to Different Lateral Force Resisting Elements

in case of buildings whose floors are capable of providing rigid horizontal diaphragm action, the total shear in any horizontal plane shall be distributed to the various vertical elements of lateral force resisting system, assuming the floors to be infinitely rigid in the horizontal plane

In case of building whose floor diaphragms can not be treated as infinitely rigid in their own plane, the lateral shear at each floor shall be distributed to the vertical elements resisting the lateral forces, considering the in-plane flexibility of the diagram

3.14 Dynamic

Analysis-Dynamic analysis shall be performed to obtain the design seismic force, and its distribution todifferent levels along the height of the building and to the various lateral load resistingelements, for the following

Buildings:

a) Regular buildings -Those greater than 40 m in height in Zones IV and V and those

Greaterthan 90 m in height in Zones II and 111

b) Irregular buildings – All framed buildings higher than 12m in Zones IV and V and

thosegreater than 40m in height in Zones 11 and III

The analytical model for dynamic analysis of buildings with unusual configuration should besuch that it adequately models the types of irregularities present in the building configuration.Buildings with plan irregularities cannot be modelled for dynamic analysis

For irregular buildings, lesser than 40 m in height in Zones 11and III, dynamic analysis, eventhough not mandatory, is recommended Dynamic analysis may be performed either by theTime History Method or by the Response Spectrum Method However, in either method, thedesign base shear (VB) shall be compared with abase shear (VB)

Time History

Method-Time history method of analysis shall be based on an appropriate ground motion and shall be performed using accepted principles of dynamics

Response Spectrum

Method-Response spectrum method of analysis shall be performed using the design spectrum

specified, or by a site-specific design spectrum mentioned

Walls and Columns: M40/M35/M30 fck=40/35/30N/mm2

Reinforcement: Yield strength of 500 N/mm2 (TMT bars)

5.6.2 FIRE REQUIREMENTS:

A minimum two hours fire rating is adopted for members i.e., Slabs, beams, columns and walls

Nominal cover to the reinforcements is:

a) DEAD AND IMPOSED LOADS:

Unit weight of materials:

As per IS: 875 (part 1) - 1987

Ceiling and services: 0.20kN/m2 (0.012*20.40)

Solid block wall, 200 thk: 3.60kN/m2 (0.20*18)

Solid block wall, 150 thk: 2.70kN/m2 (0.15*18)

Solid block wall, 100 thk: 1.80kN/m2 (0.10*18)

b) WALL LOADS PER METER HEIGHT, PER METER LENGTH:

200mm thick Masonry wall:

Self weight of wall: 3.60kN/m2

Total thickness of plaster: 0.035m

(Inside 15 mm + outside 20 mm)

Weight of plaster: 0.035 x 20.40=0.71 kN/m2

150mm thick Masonry wall:

Self weight of wall: =2.70kN/m2

Total thickness of plaster: 0.035m

(Inside 15 mm + outside 20 mm)

Weight of plaster: 0.035 x 20.40=0.71 kN/m2

100mm thick Masonry wall:

Self weight of wall: = 1.80kN/m2

Total thickness of plaster: 0.035m

(Inside 15 mm + outside 20 mm)

Weight of plaster: 0.035 x 20.40=0.714kN/m2

c) FLOORS:

SUPERIMPOSED DEAD LOADS:

Living / Dining / Bed rooms / Study Rooms / Kitchens

Lobby / Sit out / Passages/ Store room:

Cinder filling (sunk -150 mm)=0.15*10=1.50kN/m2

Services + Ceiling plaster =0.20kN/m2

Total =2.85kN/m2 Say 2.85kN/m2

Terrace area:

WPC+CINDER (assume average thickness 125mm)=0.125*22=2.75kN/m2Services + Ceiling plaster =0.50kN/m2

Total=3.25 kN/m2 Say 3.25kN/m2

Extended Basement Area:

WPC (assume average thickness 125mm)=0.125*22=2.70kN/m2

Soil fill (600mm) =0.6*20=12.0kN/m2

Services + Ceiling plaster=0.20kN/m2

d) IMPOSED LIVE LOADS:

Living / Dining / Bed rooms / Study Rooms / Kitchens = 2.00 kN/m2

Say 2.00 kN/m2Bath & Toilets = 2.00kN/m2 Say 2.00kN/m2

Corridor / Lobby / Balconies /Extended basement area=3.00kN/m2

Say 3.00 kN/m2Staircases head room area=3.00kN/m2 Say 3.00kN/m2

Terrace area

Roof accessible=1.5kN/m2 Say 1.50kN/m2

Roof not accessible=0.75kN/m2Say 0.75kN/m2

Lift machine Room Area=10kN/m2Say 10.00kN/m2

Lift machine Room roof area=1.5kN/m2Say 1.50kN/m2

(for supporting the machine lifting hook)

5.6.5 LOAD COMBINATIONS:

5.6.6 WIND LOADS (as per IS: 875 (part 3) – 1987:

Appendix - A Basic Wind Speed (Vb): 39m/s

Cl: 5.3 Design Wind Speed (Vz):Vb*k1*k2*k3

Table - 1 Risk Co-efficient factor (k1): 1

(For 50 Years of Design Life)

Table – 2 Terrain, Height & Structure size factor (k2): varies with height

Varies with height (For Category 3, Class - C)

Topography factor (k3):1

Cl: 5.4 Design Wind Pressure (pz): 0.6*Vz2

WIND LOADS (as per IS: 875 (part 3) - 1987

Location of Structure - Cochin - Kerala -INDIA

Total height of building = 82.30m

Height above mean Ground level = 75.00m

Plan dimension of building = 40.80 x14.30m Y x X

Height / Min Lateral dimension Ratio =5.755>5

Fundamental time period (T) Tx =0.09*H/Sqrt (d) =1.785

Natural frequency (nx) =1/T=0.56 < 1 Hz

Ty = 1.057 & ny =0.946 < 1 Hz

The Building is subjected to the Dynamic effects

Gust factor method:

Basic wind speed (Vb) = 39m/s

Design Hourly mean Wind speed (V1z) = Vb x k1 x k2' x k3

Risk Co-efficient factor (k1) = 1.0 (for 50 Years of Design Life)

Terrain, Height & Structure size factor (k2) =Varies with height

Background factor, B =0.75 =0.70

φ =0.0 =0.00

Size reduction factor, S =0.028 =0.140

Gust energy factor, E =0.042 =0.060

Wind Force F = Cf * Ae * Pz * G

Table: 5.5 wind forces in X and Y direction in each floor level

Level Elevation Height k2' Vz' pz' Force @ floor in kN

Y X

Acceleration at terrace Y dir a = 0.181 < 0.1962 m/sec2

Acceleration at terrace X dir a = 0.083 < 0.1962 m/sec2Structure is safe against base shear caused due to wind force

5.6.7 SEISMIC FORCES (as per IS 1893 (Part 1) -2002):

ANNEX - E Zone of the Location: Zone III

Cl: 6.4.2 Design horizontal Seismic Co-efficient (Ah): Z*I*Sa/2*R*g

ANNEX - E Z = Zone factor: 0.16

(DESIGNING FOR ONE ZONE

Table - 6 (ii) I = Importance factor: 1.0

HIGHER)

Table - 7 (viii) R = Response Reduction Factor :(SMRF) 5.0

Fig 2 Sa/g = Average Response Acceleration Coefficient

Cl: 7.5.3 Design Seismic Base Shear = Ah W

Calculation of Base Shear:

Seismic weight is calculated as per the cl 7.4 of IS: 1893-2002

Mass of the structure is calculated based on the reactions from the staad model

Live load of 25% is taken for seismic mass calculation as the loads on the floors are 2.0kN/m2 and also the live load from the terrace is neglected

Total Seismic Weight, W = 181526 KN

Zone factor, Z = 0.16

I = 1.0

h = 72.0 m

Base dimension along X – direction = 14.30m

Base dimension along Y – direction = 40.80m

Soil type = medium 2

Max drift in X direction =0.894mm

Max drift in Y direction =1.019mm

Using with brick infill panel formula Tax =2.040sec

Using with brick infill panel formula Tax=2.040sec

For Hard soils Sa/g (x) = 0.667

For Hard soils Sa/g (z) = 0.667

Ah(x) = 0.011

Ah(z) = 0.011

Base Shear in X – direction = 2000kN

Base Shear in Y – direction = 1940kN

From ETABS Static analysis:

Base Shear in X - directio)(staad output) =2105kN

Base Shear in Y - direction (staad output) =2105kN

Dynamic (Specx&Specy)

Base Shear in X - direction (staad output) =1253kN

Base Shear in Y - direction (staad output) =1195kN

Scale up in X direction = 1.6800 Say 1.65

Scale up in Y direction = 1.7615 Say 1.73

Dynamic (Specx1 & Specy1)

Base Shear in X - direction (staad output) = 2104kN

Base Shear in Y - direction (staad output) = 2207kN

Scale up in X direction = 1.0005 Say 1.00

Scale up in Y direction =0.9538 Say 0.95

Check for storey drifts

Max Drift = 0.001019 < 0.004 Safe

ANALYSIS OF G + 10 RCC FRAMED BUILDING USING

STAAD.Pro

Fig 4.1: plan of theLow Cost Multi Stored Building

All columns = 0.50 * 0.50 m

All beams = 0.6 * 0.3 m

All slabs = 0.10 m thick

Terracing = 0.2 m thick avg

Parapet = 0.10 m thick RCC

Fig 4.2: Elevation of the Low Cost Multi Stored Building

4.1 Physical parameters of building:

Live load on the floors is 3 kN/m2

Live load on the roof is 1.5 kN/m2

Grade of concrete and steel used:

Used M25 concrete and Fe 415 steel

4.2 Generation of member property:

Fig 4.3: Generation of member propertyLow Cost Multi Storedl Building

Generation of member property can be done in STAAD.Pro by using the window as shown

above The member section is selected and the dimensions have been specified The beamsare having a dimension of 0.6 * 0.3 m and the columns are having a dimension of 0.5 * 0.5 m

at the ground floor and at the other top floors they are having a dimension of 0.5 * 0.5 m

4.3 Supports:

The base supports of the structure were assigned as fixed The

supports were generated using the STAAD.Pro support generator

Fig 4.4: fixing supports of the structureLowCost Multi Stored Building

4.4 Materials for the structure:

The materials for the structure were specified as concrete with their various constants as perstandard IS code of practice

Dead load from slab:

Dead load from slab can also be generated by STAAD.Pro by specifying the floor thickness

and the load on the floor per sq m Calculation of the load per sq m was done considering theweight of beam, weight of column, weight of RCC slab, weight of terracing, external walls, internal walls and parapet over roof.

Fig 4.6: input window of floor load generator

Fig 4.7: load distribution by trapezoidal method

Fig 4.8: the structure under DL from slab

Live load:

The live load considered in each floor was 4 KN/sq m and for the terrace level itwas considered to be 1.5 KN/sq m The live loads were generated in a similar manner as done in the earlier case for dead load in each floor This may be done from the member load button from the load case column