STRUCTURAL ANALYSIS AND DESIGN OF MULTI STOREY

RESIDENTIAL BUILDINGSUBMITTED BY

Y s rohith kumarKanak d r

Shivunaika bTerbi rime

Under the guidance of:Mr. bipin g k

Asst. Professorgssit

OBJECTIVE The principal objective of the project is

to gain the idea of art and science of designing multi-storeyed structure with economy, elegance, safety, serviceability and durability.

It also deals with problems involved and to gain ability over solving the problems.

This has been an excellent opportunity for us to put into the engineering knowledge which has been acquired during the curriculum. 

FLOW CHART OF OUR PROJECT

PLAN

LOCATING THE POSITIONS OF COLUMNS AND BEAMS AND FIXING

DEPTH

Based on functionality and structural requirements, the location and orientation of column and beam are decided.

In addition, the aesthetic point of view and parking requirements in the basement were also considered while fixing up the above locations.

Depth of columns and beams were fixed using l/d ratio and IS:456 guidelines

LOAD CALCULATION

The following loads were considered for analysis and design of the structure under consideration.

Dead loadLive load

Dead loadsDead loads of various types of wall are shown below

imposed loadsThe various imposed loads considered for project are shown in table

MODELLING AND ANALYSIS USING STAAD.Pro

Creation of modelAssigning propertiesDefining end conditionDefining supportsGeneration of wind and seismic loadAssigning of defined loadsChecking the model for errorsRunning the analysis

Skeletal view & 3D VIEW OF THE STRUCTURE

Dead load on structure

Imposed load on structure

ANALYSIS RESULTSSHEAR FORCE DIAGRAM

BENDING MOMENT DIAGRAM

DESIGNINTRODUCTION

To assess the dead loads and other external loads and forces likely to be applied on the structure.

To determine the design loads from different combinations of loads.

To estimate structural responses (bending moment, shear force, axial thrust etc.) due to the design loads.

To determine the cross-sectional areas of concrete sections and amounts of reinforcement needed.

Limit State Method

Limit State Method is used in the design of this structure as per the guidelines of IS-456:2000.

There are two main limit states: Limit state of collapse and Limit state of serviceability.

DESIGN OF FOOTING1.The axial load and the moment at the bottom of the column are determined.

2. A suitable safe bearing capacity of the soil is considered.

3. The area of footing is determined by equating the pressure below footing to the SBC of soil.

4. The maximum and minimum pressure below footing is from the following expressions.

Maximum Pressure, pmax = P/A + Mxx/Zxx + Myy/Zyy <= SBC

Minimum Pressure, pmin = P/A - Mxx/Zxx - Myy/Zyy > 0

5. A suitable depth of footing (D) is assumed to satisfy the two-way shear criteria and is checked against one-way shear and bending moments. The maximum depth from the above considerations is taken as the „depth of footing‟.

6. The reinforcement is determined from both one-way and bending moment considerations and the maximum of the two is provided along the length and breadth of the footing.

DESIGN OF COLUMN1. Assume the percentage steel “p” between 0.8% and 4% and distribution of reinforcement on all the four sides.

2. For the assumed cross section of the column calculate the values of d1/D, p/fck and Pu/(fck*b*D). For these values obtain the moment carrying capacities of the section about X and Y axis referring to charts in SP-16 (Chart 43, 44, 45, 46).

3. Referring to Chart 63 of SP 16, Puz/Ag is calculated corresponding to values of p, fck and fy.

4. The ratios Pu/Puz, Mux/Mux1 and Muy/Muy1 are found. Then referring to the Chart 64 of SP 16, permissible value of Mux/Mux1 is determined corresponding to the values of Muy/Muy1 and Pu/Puz. If this criterion is not satisfied, „p‟ is increased and the above procedure is repeated.

5. Based on the obtained steel percentage, Ast is calculated. The diameter and the number of longitudinal bars are decided based on the Ast obtained.

6. The lateral ties for the column are obtained from the following criteria.The diameter of lateral ties should be greater of the following, 6mm or 0.25 times diameter of main bar

The spacing of the lateral ties should be least of the following,

Least lateral dimension 16 times diameter of main bar 300 mm

DESIGN OF BEAMS Assume the depth of the beam. Calculate the effective span (le) of the beam. Calculate the loads. Calculation of moments and shear force. Check if the beams are under reinforced or over

reinforced. Calculation of reinforcement, using Mu/bd2 and

refer SP-16 for pt value in order to obtain Ast. Check for shear stress using τv=Vu/(bd) from table 19 of IS:456-2000,obtain τc. Check for deflection control.

DESIGN OF SLABS

1. Overall thickness of the slab is based on l/d ratio.

2. Loads for the design is taken from are IS: 875-1987 and are factored as per IS: 456-2000.

3. Calculation of moment: The moment values for one-way slab are

obtained from the principle of mechanics. The moment values for two-way slab are obtained from the bending moment coefficients available in table 26, page 91 of IS: 456-2000.

4. Flexural steel: For the selected values of grade of concrete and

slab thickness, the percentage of steel pt is found out using Mu/bd2 ratio and later the required steel is calculated. The spacing of bars is found from table 37, page 74 of SP 16. This spacing is checked for IS: 456-2000 requirements.

5. Check for Shear: Usually shear check is not a concern in slabs

due to its large width, but it is checked as per the requirements specified in pages 72 and 73 of IS: 456-2000.

THANK YOU