Design of Multi Storey Building

CERTIFICATEGLOBAL COLLEGE OF ENGINEERING AND TECHNOLOGY

To whomsoever it may concernThis is to certify that Aashish Kumar Rana 1143112 has successively completed the project entitled.

STRUCTURE ANALYSIS AND DESIGN OF MULTISTORY RESIDENCIAL BUILDINGS

In the partial fulfillment of the requirements for the award of Degree of Bachelor of Civil Engineering. Under the guidance of ER. GURSHARAN SINGH. Their project report was prepared within time comprehensive manner and up to the desired level of satisfaction. I wish them all best of the future.Project coordinatorEr Gursharan Singh Civil department GCET

ACKNOWLEDGEMENT

We would like to express our profound sense of deepest gratitude to our guide and motivator Er Ajay Raghuwanshi and our project co coordinator Prof. Gursharan Singh for his valuable guidance, sympathy and co-operation for providing necessary facilities and sources during the entire period of this project.We wish to convey our sincere gratitude to all the faculties of Civil Engineering Department who have enlightened us during our studies. The facilities and co-operation received from the technical staff of Civil Engineering Department is thankfully acknowledged.We express our thanks to all those who helped us in one way or other. Last, but not least, we would like to thank the authors of various research articles and books that were referred to.

CONTENTS

ABSTRACT

S.NOTITLEPAGE NO

1Introduction5

2Loads considered7

3Input generation15

4Analysis of G+3 RCC framed building using staad pro26

5Design of G+3 building using staad pro35

6Analysis and post processing37

7Design of lift46

8Raft foundation48

9

Practical consideration 50

10Conclusion 52

11Reference 53

ABSTRACTThe principle objective of this project is to analyses and design a multi-storied reinforced concrete building [G + 3 (3 dimensional frame)] using STAAD Pro. The design involves manual load calculations, analysis and design of whole structure using STAAD Pro. The design methods used in STAAD-Pro analysis are Limit State Design conforming to Indian Standard Code of Practice.The structure is analyzed and designed and detailed for self weight, dead load, live load and seismic loads as per guidelines of Indian standard codes. Structure considered for analysis and design is 12m high residential tower located in seismic zone IV.STAAD. Pro has a very interactive user interface which allows the users to draw the frame and input the load values and dimensions. Then according to the specified criteria assigned it analyses the structure and designs the members with reinforcement details for RCC frames. We continued with our work with some more multi-storied 2-D and 3-D frames under various load combinations. Final work was the complete analysis and design of a G + 3 3-D RCC frame for various load combinations.

INTRODUCTION

Project work involves analysis and design of reinforced concrete framed structure of multi-storied [G + 3] residential tower located in seismic zone IV. using analysis and design software STAAD Pro as per Indian standard codes of practice.We have chosen STAAD Pro because of its following advantages: easy to use interface, conformation with the Indian Standard Codes, versatile nature of solving any type of problem, Accuracy of the solution.STAAD.Pro features a state-of-the-art user interface, visualization tools, powerful analysis and design engines with advanced finite element and dynamic analysis capabilities. From model generation, analysis and design to visualization and result verification, STAAD.Pro is the professionals choice for steel, concrete, timber, aluminum and cold-formed steel design of low and high-rise buildings, culverts, petrochemical plants, tunnels, bridges, piles and much more.1.1:-DETAIL OF OUR STRUCTURE

Building has been designed for gravity loads (dead load, live load, seismic load)1.2 CODES USE:-IS 456- CODE OF PRATICE FOR PLAIN AND REINFORCED CONCRETEIS 13920-IS 875 part 2 CODE OF PRACTICE FOR DESIGN LOADS PART 2 IMPOSED LOADIS 1893 (PART 1) : 2002 CRITERIA FOR EARTHQUAKE RESISTANT DESIGN OF STRUCTURES

1.3 GRADE OF MATERIALS USED:-

Grade for concrete- M 25 Grade for steel Fe 415- main steel Fe 415 secondary and tie steel

1.4 GENERAL INFORMATION

The height of the building is 12mThe height of each floor = 3mDead load on each floor except roof =7.5KNDead load on roof = 6 KNLive load for residential buildings (IS CODE 875 part -2)1) All rooms and kitchens = 2 KN/m22) Toilet and bath rooms = 2 KN/m23) Staircase, balconies, passage, storeroom = 3 KN/m2

LOADS CONCIDERED

2.1 DEAD LOADS:All permanent constructions of the structure form the dead loads. The dead load comprises of the, self weight of wall, weights of walls, floor finishes, partition walls, insulation 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, reinforced concrete made with sand and gravel or crushed natural stone aggregate, brick, finishing may be taken as 24 KN/m3, 25 KN/m3, 18 KN/m3, 1 KN/m 3 respectively.WEIGHT OF SLAB:-Calculation of dead load:-Thickness of slab is calculated for vertical deflection limits taken form IS CODE 45623.2.1The vertical deflection limits may generally be assumed to be satisfied provided that the span to depth ratios are not greater than the values obtained as below:

A) Basic values span to effective depth ratios for spans up to 10 m:2) Cantilever = 73) Simply supported = 204) Continuous =26L/d= Where, =26 for continuous span =1 as our span is less than 10 m i.e. 3.3m = 1.2(These values are calculated from IS code 456 Plain and Reinforced Concrete) = 2611.21 L =3.3 L/261.2 = d d=105 mm D = 105+20 = 125 mmLet us take D= 150 mmCalculation of dead load:- Weight of slab = 0.151125 = 3.75 KN/m2 Finishing load = 0.05 20 = 4 KN/m2

Total dead load = 7500 N/m2= 7500 KN/m2Dead load on roof 0.15 25 = 3.75 KN/m2

2.2 LIVE LOAD:-

Sl noOccupancy classificationsUniformly distributed load (UDL)Concentrated load

1

RESIDENTIAL BUILDINGa) Dwelling houses:1) All rooms and kitchen2) Toilet and bathrooms3) Corridors, passengers, staircases including the escapes and store rooms4) balconies

2.02.03.0

3.0

1.8---4.5

3.5 per meter run

IMPOSED LOADS FOR DIFFERENT OCCUPANCIES

2.3 BRICK LOAD:Density = 15.7 to 18.85 KN/m3 = 18.85KN/m3Brick load for 230mm thick wall and height 3 m = 18.850.233 =13.0065 KN/ mBrick load for 115mm thick wall having a height 3 m= 18.85 0.115 3 = 6.50 KN/m

Load of Parapet wall = 4.4 KN/m2.4 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, seismic activity.2.6 DESIGN LATERAL FORCESThe design lateral force shall first be computed for the building as a whole. This design lateral force shall then be distributed to the various floor levels. The overall design seismic force thus obtained at each floor level shall then be distributed to individual lateral load resisting elements depending on the floor diaphragm action.2.7 DESIGN SEISMIC BASE SHEARThe total design lateral force or design seismic base shear (Vb) along any principal direction shall be determined by the following expression:Vb = Ah WWhere,Ah = horizontal acceleration spectrumW = seismic weight of all the floors

Provided that for any structure with T 0.1 s , these values of Ah will not be taken less than Z/2 whatever be the value of I/RWhereZ = zone factor given in table, is for the maximum considered earthquake (MCE) and service life of structure in a zone . The factor 2 in denominator of Z is used so as to reduce MCE zone factor to the factor for design basis earthquake (DBE)I = importance factor depending upon the functional use of structure characterized by hazardous consequences of its failure, post earthquake functional needs, historical value or economicR = response reduction factor, depending on the perceived seismic damage performance of the structure , characterized by ductile or brittle deformation TablesSeismic zones level(in meters)Depth below groundN-valuesRemark

III, IV and V

Equal to or less than 5

Greater than or equal to 1015

25For values below 5m, linear interpolation is required

II ( for important structures only)Equal to or less than 5

Greater than or equal to 1015

25For values below 5m, linear interpolation is required

Seismic Zone

IIIIIIVV

Seismic activity

LowModerateSevereVery severe

Z0.100.160.240.36

ZONE FACTOR, ZSa/g = average response acceleration coefficientResponse spectra for rock and soil sites for 5% damping2.8 FUNDAMENTAL NATURAL PERIODThe approximate fundamental natural period of vibration (T,), in seconds, of a moment-resisting frame building without brick in the panels may be estimated by the empirical expression:Ta=0.075 h0.75 for RC frame buildingTa=0.085 h0.75 for steel frame buildingWhere,h = Height of building, in m. This excludes the basement storeys, where basement walls are connected with the ground floor deck or fitted between the building columns. But it includes the basement storeys, when they are not so connected. The approximate fundamental natural period of vibration (T,), in seconds, of all other buildings, including moment-resisting frame buildings with brick lintel panels, may be estimated by the empirical Expression:T=.09H/DWhere,h= Height of buildingd= Base dimension of the building at the plinth level, in m, along the considered direction of the lateral force.

2.9 DISTRIBUTION OF DESIGN FORCESVertical Distribution of Base Shear to Different Floor LevelThe design base shear (V) shall be distributed along the height of the building as per the following expression:

Qi=Design lateral force at floor i,WI=Seismic weight of floor i,hi=Height of floor i measured from base, andn=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 cannot 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.

2.10 DYNAMIC ANALYSIS-Dynamic analysis shall be performed to obtain the design seismic force, and its distribution to different levels along the height of the building and to the various lateral load resisting elements, for the followingBuildings:a) Regular buildings -Those greater than 40 m in height in Zones IV and V and those Greater than 90 m in height in Zones II and 111.b) Irregular buildings All framed buildings higher than 12m in Zones IV and V and those greater than 40m in height in Zones 11 and III.The analytical model for dynamic analysis of buildings with unusual configuration should be such that it adequately models the types of irregularities present in the building configuration. Buildings with plan irregularities cannot be modeled for dynamic analysis.For irregular buildings, lesser than 40 m in height in Zones 11and III, dynamic analysis, even though not mandatory, is recommended. Dynamic analysis may be performed either by the Time History Method or by the Response Spectrum Method. However, in either method, the design base shear (VB) shall be compared with a base shear (VB)

INPUT GENERATION

The GUI (or user) communicates with the STAAD analysis engine through the STD input file. That input file is a text file consisting of a series of commands which are executed sequentially. The commands contain either instructions or data pertaining to analysis and/or design. The STAAD input file can be created through a text editor or the GUI Modeling facility. In general, any text editor may be utilized to edit/create the STD input file. The GUI Modeling facility creates the input file through an interactive menu-driven graphics oriented procedure.First of all we will insert nodes according to the plan as per our architectural plan. And then aplly different properties to the given structure.

Placing nodes in guiAnd then with the help of transitional repeat option, create the 15 storeys of the multi storey building with ground floor

We can also add beams between nodes with the help of option shown in figure below and can complete the structure.

we can also use various methods for connecting the various floors in staad pro. This is by selecting all the nodes of the given beam, and joining them by using command connect beam in the geometry option.

STAAD editor file it will be like this as shown in the picture:

3.2 TYPES OF STRUCTUREA STRUCTURE can be defined as an assemblage of elements. STAAD is capable of analyzing and designing structures consisting of frame, plate/shell and solid elements. Almost any type of structure can be analyzed by STAAD.A SPACE structure, which is a three dimensional framed structure with loads applied in any plane, is the most general. A PLANE structure is bound by a global X-Y coordinate system with loads in the same plane. A TRUSS structure consists of truss members which can have only axial member forces and no bending in the members.A FLOOR structure is a two or three dimensional structure having no horizontal (global X or Z) movement of the structure [FX, FZ & MY are restrained at every joint]. The floor framing (in global X-Z plane) of a building is an ideal example of a FLOOR structure. Columns can also be modeled with the floor in a FLOOR structure as long as the structure has no horizontal loading. If there is any horizontal load, it must be analyzed as a SPACE structure.3.3 GENERATION OF STRUCTUREThe structure may be generated from the input file or mentioning the co-ordinates in the GUI. The figure below shows the GUI generation method.

generation of structure.

3.4SUPPORTSSupports are specified as PINNED, FIXED, or FIXED with different releases (known as FIXED BUT). A pinned support has restraints against all translational movement and none against rotational movement. In other words, a pinned support will have reactions for all forces but will resist no moments. A fixed support has restraints against all directions of movement. Translational and rotational springs can also be specified. The springs are represented in terms of their spring constants. A translational spring constant is defined as the force to displace a support joint one length unit in the specified global direction. Similarly, a rotational spring constant is defined as the force to rotate the support joint one degree around the specified global direction.3.5 LOADS: Loads in a structure can be specified as joint load, member load, temperature load and fixed-end member load. STAAD can also generate the self-weight of the structure and use it as uniformly distributed member loads in analysis. Any fraction of this self weight can also be applied in any desired direction.Joint loads: Joint loads, both forces and moments, may be applied to any free joint of a structure. These loads act in the global coordinate system of the structure. Positive forces act in the positive coordinate directions. Any number of loads may be applied on a single joint, in which case the loads will be additive on that joint.Member load: Three types of member loads may be applied directly to a member of a structure. These loads are uniformly distributed loads, concentrated loads, and linearly varying loads (including trapezoidal). Uniform loads act on the full or partial length of a member. Concentrated loads act at any intermediate, specified point. Linearly varying loads act over the full length of a member. Trapezoidal linearly varying loads act over the full or partial length of a member. Trapezoidal loads are converted into a uniform load and several concentrated loads. Any number of loads may be specified to act upon a member in any independent loading condition. Member loads can be specified in the member coordinate system or the global coordinate system. Uniformly distributed member loads provided in the global coordinate system may be specified to act along the full or projected member length.

Member load configurationArea/floor load:Many times a floor (bound by X-Z plane) is subjected to a uniformly distributed load. It could require a lot of work to calculate the member load for individual members in that floor. However, with the AREA or FLOOR LOAD command, the user can specify the area loads (unit load per unit square area) for members. The program will calculate the tributary area for these members and provide the proper member loads. The Area Load is used for one way distributions and the Floor Load is used for two way distributions.Fixed end member load:Load effects on a member may also be specified in terms of its fixed end loads. These loads are given in terms of the member coordinate system and the directions are opposite to the actual load on the member. Each end of a member can have six forces: axial; shear y; shear z; torsion; moment y, and moment z.Load Generator Moving load, Seismic:Load generation is the process of taking a load causing unit such as wind pressure, ground movement or a truck on a bridge, and converting it to a form such as member load or a joint load which can be then be used in the analysis.Moving Load Generator:This feature enables the user to generate moving loads on members of a structure. Moving load system(s) consisting of concentrated loads at fixed specified distances in both directions on a plane can be defined by the user. A user specified number of primary load cases will be subsequently generated by the program and taken into consideration in analysis.Seismic Load Generator:The STAAD seismic load generator follows the procedure of equivalent lateral load analysis. It is assumed that the lateral loads will be exerted in X and Z directions and Y will be the direction of the gravity loads. Thus, for a building model, Y axis will be perpendicular to the floors and point upward (all Y joint coordinates positive). For load generation per the codes, the user is required to provide seismic zone coefficients, importance factors, and soil characteristic parameters. Instead of using the approximate code based formulas to estimate the building period in a certain direction, the program calculates the period using Raleigh quotient technique. This period is then utilized to calculate seismic coefficient C. After the base shear is calculated from the appropriate equation, it is distributed among the various levels and roof per the specifications. The distributed base shears are subsequently applied as lateral loads on the structure. These loads may then be utilized as normal load cases for analysis and design.

3.6SECTION TYPE FOR CONCTERE DESIGNThe following types of cross sections for concrete members can be designed. For Beams Prismatic (Rectangular & Square) & T-shape For Columns Prismatic (Rectangular, Square and Circular)3.7 DESIGN PARAMETERThe program contains a number of parameters that are needed to perform design as per IS 13920. It accepts all parameters that are needed to perform design as per IS: 456. Over and above it has some other parameters that are required only when designed is performed as per IS: 13920. Default parameter values have been selected such that they are frequently used numbers for conventional design requirements. These values may be changed to suit the particular design being performed by this manual contains a complete list of the available parameters and their default values. It is necessary to declare length and force units as Millimeter and Newton before performing the concrete design.3.8 BEAM DESIGNBeams are designed for flexure, shear and torsion. If required the effect of the axial force may be taken into consideration. For all these forces, all active beam loadings are prescanned to identify the critical load cases at different sections of the beams. For design to be performed as per IS: 13920 the width of the member shall not be less than 200mm. Also the member shall preferably have a width-to depth ratio of more than 0.3.3.9 DESIGN FOR FLEXUREDesign procedure is same as that for IS 456. However while designing following criteria are satisfied as per IS-13920:1. The minimum grade of concrete shall preferably be M20.2. Steel reinforcements of grade Fe415 or less only shall be used.3. The minimum tension steel ratio on any face, at any section, is given by:min = 0.24fck/fyThe maximum steel ratio on any face, at any section, is given by max = 0.0254. The positive steel ratio at a joint face must be at least equal to half the negative steel at that face.5. The steel provided at each of the top and bottom face, at any section, shall at least be equal to one-fourth of the maximum negative moment steel provided at the face of either joint.3.10 DESIGN FOR SHEARThe shear force to be resisted by vertical hoops is guided by the IS 13920:1993 revision. Elastic sagging and hogging moments of resistance of the beam section at ends are considered while calculating shear force. Plastic sagging and hogging moments of resistance can also be considered for shear design if PLASTIC parameter is mentioned in the input file. Shear reinforcement is calculated to resist both shear forces and torsional moments.

3.11 COLUMN DESIGNColumns are designed for axial forces and biaxial moments per IS 456:2000. Columns are also designed for shear forces. All major criteria for selecting longitudinal and transverse reinforcement as stipulated by IS: 456 have been taken care of in the column design of STAAD. However following clauses have been satisfied to incorporate provisions of IS 13920:1 The minimum grade of concrete shall preferably be M202. Steel reinforcements of grade Fe415 or less only shall be used.3. The minimum dimension of column member shall not be less than 200 mm. For columns having unsupported length exceeding 4m, the shortest dimension of column shall not be less than 300 mm.4. The ratio of the shortest cross-sectional dimension to the perpendicular dimension shall preferably be not less than 0.5. The spacing of hoops shall not exceed half the least lateral dimension of the column, except where special confining reinforcement is provided.6. Special confining reinforcement shall be provided over a length lo from each joint face, towards mid span, and on either side of any section, where flexural yielding may occur. Thelength lo shall not be less than a) larger lateral dimension of the member at the section where yielding occurs, b) 1/6 of clear span of the member, and c) 450 mm.7. The spacing of hoops used as special confining reinforcement shall not exceed of minimum member dimension but need not be less than 75 mm nor more than 100 mm.3.12 DESIGN OPERATIONSTAAD contains a broad set of facilities for designing structural members as individual components of an analyzed structure. The member design facilities provide the user with the ability to carry out a number of different design operations. These facilities may design problem. The operations to perform a design are: Specify the members and the load cases to be considered in the design. Specify whether to perform code checking or member selection. Specify design parameter values, if different from the default values. Specify whether to perform member selection by optimization.These operations may be repeated by the user any number of times depending upon the design requirements.Earthquake motion often induces force large enough to cause inelastic deformations in the structure. If the structure is brittle, sudden failure could occur. But if the structure is made to behave ductile, it will be able to sustain the earthquake effects better with some deflection larger than the yield deflection by absorption of energy. Therefore ductility is also required as an essential element for safety from sudden collapse during severe shocks. STAAD has the capabilities of performing concrete design as per IS 13920. While designing it satisfies all provisions of IS 456 2000 and IS 13920 for beams and columns.3.13 GENERAL COMMENTSThis section presents some general statements regarding the implementation of Indian Standard code of practice (IS: 800-1984) for structural steel design in STAAD. The design philosophy and procedural logistics for member selection and code checking are based upon the principles of allowable stress design. Two major failure modes are recognized: failure by overstressing, and failure by stability considerations. The flowing sections describe the salient features of the allowable stresses being calculated and the stability criteria being used. Members are proportioned to resist the design loads without exceeding the allowable stresses and the most economic section is selected on the basis of least weight criteria. The code checking part of the program checks stability and strength requirements and reports the critical loading condition and the governing code criteria. It is generally assumed that the user will take care of the detailing requirements like provision of stiffeners and check the local effects such as flange buckling and web crippling.3.14 ALLOWABLE STRESSESThe member design and code checking in STAAD are based upon the allowable stress design method as per IS: 800 (1984). It is a method for proportioning structural members using design loads and forces, allowable stresses, and design limitations for the appropriate material under service conditions. It would not be possible to describe every aspect of IS: 800 in this manual. This section, however, will discuss the salient features of the allowable stresses specified by IS: 800 and implemented in STAAD. Appropriate sections of IS: 800 will be referenced during the discussion of various types of allowable stresses.

3.15 MULTIPLE ANALYSISStructural analysis/design may require multiple analyses in the same run. STAAD allows the user to change input such as member properties, support conditions etc. in an input file to facilitate multiple analyses in the same run. Results from different analyses may be combined for design purposes. For structures with bracing, it may be necessary to make certain members inactive for a particular load case and subsequently activate them for another. STAAD provides an INACTIVE facility for this type of analysis.3.13 POST PROCESSING FACILITIESAll output from the STAAD run may be utilized for further processing by the STAAD.Pro GUI.Stability Requirements:Slenderness ratios are calculated for all members and checked against the appropriate maximum values IS: 800 summarize the maximum slenderness ratios for different types of members. In STAAD implementation of IS: 800, appropriate maximum slenderness ratio can be provided for each member. If no maximum slenderness ratio is provided, compression members will be checked against a maximum value of 180 and tension members will be checked against a maximum value of 400.Deflection Check:This facility allows the user to consider deflection as criteria in the CODE CHECK and MEMBER SELECTION processes. The deflection check may be controlled using three parameters. Deflection is used in addition to other strength and stability related criteria. The local deflection calculation is based on the latest analysis results.Code Checking:The purpose of code checking is to verify whether the specified section is capable of satisfying applicable design code requirements. The code checking is based on the IS: 800 (1984) requirements. Forces and moments at specified sections of the members are utilized for the code checking calculations. Sections may be specified using the BEAM parameter or the SECTION command. If no sections are specified, the code checking is based on forces and moments at the member ends.

ANALYSIS OF G + 3 RCC FRAMED BUILDING USING STAAD.Pro

4.1 Physical parameter of the structure

All columns = 500300mmAll beams = 450300 mmAll slabs = 150mmTerracing = 200 mmParapet = 100 mm

elevation of the G+3 storey building

Height = 12(1.0m parapet being non- structural for seismic purposes, is not considered of building frame height)Live load on the floors is 3 kN/m2Live 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

Generation of member property

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 beams are having a dimension of 450300 mm and the columns are having a dimension of 500300mm

4.3 SUPPORTSThe base supports of the structure were assigned as fixed. The supports were generated using the STAAD.Pro support generator. The base supports of the structure were assigned as fixed. The supports were generated using the STAAD.Pro support generator.

Fixing support of the structure Materials for the structure:The materials for the structure were specified as concrete with their various constants as per standard IS code of practice.4.4 LOADINGSThe loadings were calculated partially manually and rest was generated using STAAD.Pro load generator. The loading cases were categorized as:Self-weightDead load from slabLive loadSeismic loadLoad combinations

Window showing different load cases

Self-weightThe self weight of the structure can be generated by STAAD.Pro itself with the self weight command in the load case column.

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 the weight of beam, weight of column, weight of terracing, external walls, internal walls and parapet over roof.

Fig 4.5 Input window of load gererator:

Load distribution by trapezoidal method

Structure under DL

Live load: The live load considered in each floor was 3 KN/sq m and for the terrace level it was 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.

structure under live load

Seismic load:The seismic load values were calculated as per IS 1893-2002. STAAD.Pro has a seismic load generator in accordance with the IS code mentioned.Description:The seismic load generator can be used to generate lateral loads in the X and Z directions only. Y is the direction of gravity loads. This facility has not been developed for cases where the Z axis is set to be the vertical direction using the SET Z UP command.Methodology:The design base shear is computed by STAAD in accordance with the IS: 1893(Part 1)-2002.V = Ah*WWhere, Ah = (Z*I*Sa)/ (2*R*g) STAAD utilizes the following procedure to generate the lateral seismic loads.User provides seismic zone co-efficient and desired "1893(Part 1)-2002 specs" through the DEFINE 1893 LOAD command.Program calculates the structure period (T).Program calculates Sa/g utilizing T.Program calculates V from the above equation. W is obtained from the weight data provided by the user through the DEFINE 1893 LOAD command.The total lateral seismic load (base shear) is then distributed by the program among different levels of the structure per the IS: 1893(Part 1)-2002 procedures.

4.6 LOAD COMBINATIONSThe structure has been analyzed for load combinations considering all the previous loads in proper ratio. In the first case a combination of self-weight, dead load, live load and wind load was taken in to consideration. In the second combination case instead of wind load seismic

Load combination under seismic load

GUI showing the analyzing window DESIGN OF G+3 BUILDING USING STAAD.Pro

The structure was designed for concrete in accordance with IS code. The parameters such as clear cover, Fy, Fc, etc were specified. The window shown below is the input window for the design purpose. Then it has to be specified which members are to be designed as beams and which member are to be designed as columns.

Input window for design purpose

Design specification in STAAD.pro

ANALYSIS, POST PROCESSING AND DESIGN

When the earthquake forces are considered on a structure these shall be combined as per clause 6.3.1.1 and 6.3.1.2. Where the terms dead load, live load and earth quake load for this response LOAD COMBINATION for seismic load1 D L + 0.25 L L L L-consist of live load of all storeys except top storey. In limit state design of RCC and prestressed concrete structures the following load combinations shall be accounted for:1)1.5 (D L + I L)2)1.2(D L + I L +- E L)3)1.5 ( D L +- E L)4)0.9 D L +- 1.5 E LPositive and negative sign indicates the seismic force( E L) acting in X and Y direction.

6.1 DESIGN OF COLUMN:

For designing column, properties are given to the columns i.e 500x300

3-d rendered view

6.2 ANALYSIS AND DESIGN RESULT

C O L U M N N O. 9 D E S I G N R E S U L T SM25 Fe415 (Main) Fe415 (Sec.)

LENGTH: 3000.0 mm CROSS SECTION: 300.0 mm X 500.0 mm COVER: 40.0 mm** GUIDING LOAD CASE: 25 END JOINT: 6 SHORT COLUMNREQD. STEEL AREA : 341.17 Sq.mm.REQD. CONCRETE AREA: 42646.40 Sq.mm.MAIN REINFORCEMENT : Provide 8 - 12 dia. (0.60%, 904.78 Sq.mm.)(Equally distributed)TIE REINFORCEMENT : Provide 8 mm dia. rectangular ties @ 190 mm c/c

SECTION CAPACITY BASED ON REINFORCEMENT REQUIRED (KNS-MET)----------------------------------------------------------Puz : 1789.85 Muz1 : 103.83 Muy1 : 60.73

INTERACTION RATIO: 0.24 (as per Cl. 39.6, IS456:2000)

SECTION CAPACITY BASED ON REINFORCEMENT PROVIDED (KNS-MET)----------------------------------------------------------WORST LOAD CASE: 25END JOINT: 7 Puz : 1958.93 Muz : 136.04 Muy : 76.80 IR: 0.36

6.3 DESIGN OF BEAMS

For designing beam, the properties of beams are: 450x300

3-d rendered view

ANALYSIS AND DESIGN RESULTS

BEAM RESULTS B E A M N O. 5 D E S I G N R E S U L T SM25 Fe415 (Main) Fe415 (Sec.)LENGTH: 4000.0 mm SIZE: 300.0 mm X 400.0 mm COVER: 25.0 mmSUMMARY OF REINF. AREA (Sq.mm)----------------------------------------------------------------------------SECTION 0.0 mm 1000.0 mm 2000.0 mm 3000.0 mm 4000.0 mm----------------------------------------------------------------------------TOP 383.48 0.00 0.00 0.00 554.67REINF. (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm)

BOTTOM 0.00 227.35 257.00 227.35 0.00REINF. (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm) (Sq. mm)----------------------------------------------------------------------------SUMMARY OF PROVIDED REINF. AREA----------------------------------------------------------------------------SECTION 0.0 mm 1000.0 mm 2000.0 mm 3000.0 mm 4000.0 mm----------------------------------------------------------------------------TOP 4-12 2-12 2-12 2-12 5-12REINF. 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s)

BOTTOM 2-10 3-10 4-10 3-10 2-10REINF. 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s) 1 layer(s)

SHEAR 2 legged 8 2 legged 8 2 legged 8 2 legged 8 2 legged 8REINF. @ 140 mm c/c @ 140 mm c/c @ 140 mm c/c @ 140 mm c/c @ 140 mm c/c----------------------------------------------------------------------------SHEAR DESIGN RESULTS AT DISTANCE d (EFFECTIVE DEPTH) FROM FACE OF THE SUPPORT

SHEAR DESIGN RESULTS AT 615.0 mm AWAY FROM START SUPPORTVY = 55.69 MX = -0.50 LD= 25Provide 2 Legged 8 @ 140 mm c/c

SHEAR DESIGN RESULTS AT 615.0 mm AWAY FROM END SUPPORTVY = -65.40 MX = -0.50 LD= 25Provide 2 Legged 8 @ 140 mm c/c

GEOMETRY OF BEAM NO. 5

LOADING OF BEAM NO.5

SHEAR BENDING OF BEAM NO. 5

DEFLECTION OF BEAM NO. 5

CONCRETE DESIGN OF BEAM NO. 5

DESIGN OF LIFTSHEAR WALLSThese are the solids walls, which usually extend over a full height of a building. They are commonly located at the lift/staircase core regions. Shear walls are also frequently placed along the transverse direction of a building, either as exterior walls or interior walls. These walls are stiff, having considerable depth in the direction of lateral load, they resist loads by bending like vertical cantilevers, fixed at the base.

Shear walls in structure

3-d rendered view

Stress in shear walls

Raft FoundationRaft foundation is a thick concrete slab reinforced with steel which covers the entire contact area of the structure like a thick floor. Sometimes area covered by raft may be greater than the contact area depending on the bearing capacity of the soil underneath. The reinforcing bars runs normal to each other in both top and bottom layers of steel reinforcement. Sometimes inverted main beams and secondary beams are used to carry column loads that require thicker foundation slab considering economy of the structure. Both beams cast monolithically with raft slab.

Raft foundation is required where soils have low bearing capacity and have to support heavy structural loads. Normally structures on marshy land, soft clay and land that are made up of sanitary land fill or other materials (like debris, unconsolidated soil and solid waste etc. where differential settlement is suspected)-require raft foundation. In one words, where deep foundation like pile foundation are not economical and feasible and isolated column footing is impracticable due to large footing size or over-lapping of neighbor footing, raft foundation is the economical

The cover provided for the raft foundation is 2 m from each side of the building. And the thickness provided is of 1.5 m. The vertical loads provided on the foundation are given by the columns of the building, which are obtained by the analysis file from staad pro.

The above picture represents the raft foundation of the structure with the various loads of the column on it.

This shows the stress distribution on the raft foundation. The area colored as red, indicates the point where differential settlement can take place in the future. At this point pile foundations can be provided so as to remove the possibility of failure.

Practical considerationsGenerally the design provided by the staad pro has a few limitations i.e for a given continous beam, it provides us the reinforcement to be used of bars varying in diameter and number. But this is practically not possible. So with the given procedure we can solve this problem.For the calculation of the exact number of bars required to be provided. We have to calculate some basic values for different types of bars to be used. The formula used for the purpose is given as = d2/127 Where d = diameter of bars provided

For eg:- if the bars provided on reinforcement is 10, 12 or 16 mm. then the calculations are as followsFor 10 mm bars = 102 /127 = .787For 12 mm bars = 122 /127 = 1.133For 16 mm bars = 162 /127 = 2.015These are the basic values to be used, and these are multiplied by the number of bars given in the drawing. So if the number of bars given in the drawing as 6 # 10, the value given by the formula for the 10 mm diameter bar is multiplied by 6.

6#10= 6*.787= 4.7225#16= 5*2.015=10.075This value obtained is divided by the maximum bar value of the given formula. And from this we get the number of bars that are to be provided in the beam. The bar to be provided in the section is the maximum diameter bar provided in the drawing.

The lower reinforcement is provided with the maximum diameter bars and the upper reinforcement is provided with the minimum diameter bars

CONCLUSION

STAAD PRO has the capability to calculate the reinforcement needed for any concrete section. The program contains a number of parameters which are designed as per IS: 456(2000). Beams are designed for flexure, shear and torsion.

8.1 Design for Flexure: Maximum sagging (creating tensile stress at the bottom face of the beam) and hogging (creating tensile stress at the top face) moments are calculated for all active load cases at each of the above mentioned sections. Each of these sections are designed to resist both of these critical sagging and hogging moments. Where ever the rectangular section is inadequate as singly reinforced section, doubly reinforced section is tried. 8.2 Design for Shear: Shear reinforcement is calculated to resist both shear forces and torsional moments. Shear capacity calculation at different sections without the shear reinforcement is based on the actual tensile reinforcement provided by STAAD program. Two-legged stirrups are provided to take care of the balance shear forces acting on these sections. 8.3 Beam Design Output: The default design output of the beam contains flexural and shear reinforcement provided along the length of the beam. 8.4 Column Design: Columns are designed for axial forces and biaxial moments at the ends. All active load cases are tested to calculate reinforcement. The loading which yield maximum reinforcement is called the critical load. Column design is done for square section. Square columns are designed with reinforcement distributed on each side equally for the sections under biaxial moments and with reinforcement distributed equally in two faces for sections under uni-axial moment. All major criteria for selecting longitudinal and transverse reinforcement as stipulated by IS: 456 have been taken care of in the column design of STAAD.REFERENCE

LIMIT STATE DESIGN OF REINFORCED CONCRETEBY DR. B.C PUNMIA, ASHOK KUMAR JAIN, ARN KUMAR JAIN

DYNAMICS OF STRUCTUREBY A.K CHOPRA

EARTHQUAKE RESISTANT AND DESIGN BY PANKAJ AGGARWAL

STAAD Pro Technical reference manual - Published by: R.E.I.

IS 456 - BUREAU OF INDIAN STANDARDS MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG NEW DELHI 110002

IS 1893-2000 - BUREAU OF INDIAN STANDARDS MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG NEW DELHI 110002

IS 1893-2002 - BUREAU OF INDIAN STANDARDS MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG NEW DELHI 110002 3 1143112