Structural Modeling, Analysis and Design “Food Court” Building For ITL Infosys, Hyderabad Submitted By: Amit Kumar Saran Ashwini Kumar Bharat Sondhi M.Tech. (IT in Building Science), IIIT,Hyderabad Index 1. Structural Modeling Structural Details of the building Modeling with STAAD Modeling with AutoCAD 2. Structural Analysis Wind Load Analysis Seismic Load Analysis Base Shear Calculations Load Distribution Possible Load Combinations Analysis results 3. Structural Design Design of beams Design of ring beam Design of Columns Design of Footings Design of Slab
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Structural Modeling, Analysis and Design
“Food Court” Building For ITL Infosys, Hyderabad
Submitted By: Amit Kumar Saran
Ashwini Kumar Bharat Sondhi
M.Tech. (IT in Building Science), IIIT,Hyderabad
Index
1. Structural Modeling Structural Details of the building
Modeling with STAAD Modeling with AutoCAD 2. Structural Analysis
Wind Load Analysis Seismic Load Analysis Base Shear Calculations Load Distribution Possible Load Combinations Analysis results
3. Structural Design Design of beams Design of ring beam Design of Columns Design of Footings Design of Slab
1. Structural Modeling
Reliability and accuracy of design of a building structure largely depends on how accurately and meticulously it has been perceived and modeled. This structure has been modeled in both STAAD as well as AutoCAD after several careful inspections of the site as well as architectural drawings. Some of the salient features of the building are:
1. A shell structure used as a dome of the building 2. A Space Frame structure consisting of a food court cum auditorium, aerobics room and cyber-cafe Structural Details of the building: Total no. of members / elements: 548 Total no. of joints: 388 Total no. of supports: 56 Total no. of degrees of freedom: 1992 Size of stiffness matrix: 1, 79,280 There are 4 representative Ring Beams: RB1, RB2, RB3, and RB4 each in 3 rings. No. of columns in the innermost ring = 4 No. of columns in last but penultimate ring = 8 No. of columns in penultimate ring = 16 No. of columns in the outermost ring = 16 No. of columns in the corners = 12 There are 3 representative radial beams: B1, B2 and B3 Ring Beams in the structure were modeled as straight line elements, each of them are at an angle of 5.625 degrees.
Structural Modeling in STAAD Structure was modeled in STAAD-III by using its in-built modeling facilities. It was modeled using file-input as well as user-interface facility provided in STAAD.
209 TO 224 PRI YD 1.2 ZD .450 225 TO 232 PRI YD .600 ZD .300 249 TO 312 PRI YD .900 ZD .600 193 198 201 206 PRI YD .500 ZD .300 194 TO 197 199 200 202 TO 205 207 208 PRI YD .800 ZD .300 233 TO 248 PRI YD 1.200 ZD .450 313 TO 376 PRI YD .900 ZD .600 377 TO 380 PRI YD .600 381 TO 396 PRI YD .900 ZD .300 429 TO 436 485 TO 488 497 TO 500 PRI YD .900 ZD .300 437 TO 442 444 TO 452 489 TO 496 501 TO 508 PRI YD .900 ZD .300 443 PRI YD .900 ZD .300 397 TO 399 401 TO 403 405 TO 407 409 TO 411 PRI YD .800 ZD .300 453 TO 484 PRI YD .800 ZD .300 413 TO 415 417 TO 419 421 TO 423 425 TO 427 PRI YD .800 ZD .300 523 TO 526 539 541 TO 543 PRI YD .900 ZD .300 529 TO 534 536 TO 538 546 TO 548 PRI YD .800 ZD .300 511 512 517 518 PRI YD .300 ZD .600 515 520 PRI YD .600 ZD .300 514 PRI YD .600 ZD .300 509 PRI YD .600 ZD .300 510 PRI YD .800 ZD .300 513 516 519 PRI YD .800 ZD .300 521 522 527 528 535 540 544 545 PRI YD .900 ZD .300 400 404 408 412 416 420 424 428 PRI YD .900 ZD .300 CONSTANT E CONCRETE ALL DENSITY CONCRETE ALL POISSON CONCRETE ALL SUPPORT 193 TO 232 FIXED 377 TO 380 FIXED 364 381 TO 388 FIXED 361 TO 363 FIXED *DEFINE WIND LOAD *TYPE 1 *INT 0. 1.1 HEI -4.5 20. *EXPOSURE 1. YR -5. 20.5 *LOAD 1 WIND LOAD IN Z *WIND LOAD Z 1. TYPE 1 LOAD 1 DL SHELL MEMBER LOAD 249 TO 312 UNI GY -24. LOAD 2 SELF SELFWEIGHT Y -1. LOAD 3 DL LL FF SLAB MEMBER LOAD 1 TO 64 UNI GY -7.02881 65 TO 128 UNI GY -11.5651 129 TO 192 UNI GY -7.2621 313 TO 376 UNI GY -2.68 413 TO 428 UNI GY -24.9444 453 TO 484 UNI GY -24.9444 445 TO 452 UNI GY -24.9444 429 TO 437 UNI GY -18.28 437 TO 444 UNI GY -27.90 381 TO 396 UNI GY -18.28 397 TO 412 UNI GY -27.9 499 501 490 502 491 503 492 504 489 UNI GY -27.9 496 508 493 505 507 495 506 494 UNI GY -24.9444
485 497 486 498 487 499 488 500 UNI GY -18.28 521 TO 528 539 TO 545 535 UNI GY -7.2621 529 TO 534 536 TO 538 546 TO 548 UNI GY -14.4 LOAD COMB 4 DL SHELL + SELF + DL LL FF SLAB 1 1.5 2 1.5 3 1.5 PERFORM ANALYSIS PRINT ALL LOAD LIST ALL PRINT ANALYSIS RESULTS PRINT MEMBER FORCES ALL PRINT SUPPORT REACTIONS FINISH Modeling with AutoCAD:
The space frame structure of the building was also modeled in AutoCAD for better CAD facilities provided with the software. The drawings in *.DXF format were then imported in STAAD software, where additional properties were applied to CAD model of the structures. The properties applied to the imported CAD drawing are as follows: 1. Sectional properties 2. Support conditions 3. Material Properties 4. Loading conditions Loading units were taken as per IS codes as follows: unit weight of concrete = 25 kN/m3
unit weight of 200 mm thick solid concrete block wall = 24 kN/m3
floor finish = 1 kN/m2
Live load at floor = 3.5 kN/m2
Live load at roof level = 1.5 kN/m2
2. STRUCTURAL ANALYSIS
Structure was analyzed for self-weight, live load, wind load and seismic loads. Analysis was performed in STAAD-III. Details of analysis are as follows: Wind Load Analysis: For wind load analysis all data is taken from Indian standard code : IS – 875 (Part – 3) – 1987 Design Wind Speed = Vb * k1 * k2 * k3 Where; Vb = Basic wind speed in m / s k1 = risk coefficient = .91 k2 = THS Factor = 1.02 k3 = Topography Factor = 1 Vb = 44 m / s for Hyderabad Terrain Category : 2 (open terrain with scattered obstructions of height between 1.5m to 10m) Class of Building : B (structures having maximum dimensions between 20m to 40m) Wind intensities: Design Wind Pressure = 0.6 * Vz2
Exposure Factor At all Joints = 1 Wind load intensity at 1st Floor = 1.0008 kN / m2
The wind load on the building shall be calculated for the building as a whole. Wind Load on the Building = Cf * Ae * Pd Where; Cf = Force Coefficient Ae = Effective Frontal Area Pd = Design Wind Pressure The value of Cf = 0.5 from Table – 23 of IS: 875 (Part – 3) for buildings of circular shape. Wind Load at each floor is distributed among the columns at that floor accordingly their relative stiffness. Seismic Load Analysis:
The Structure is analyzed as an equivalent static approach employing the use of a Seismic Coefficient method. Terminology: Basic Seismic Coefficient (a0) To give the basic design acceleration as a fraction of the acceleration due to gravity Importance Factor (I) To modify the basic seismic coefficient and seismic zone factor, depending upon the importance of structure Soil Foundation System Factor (ß) To modify the a0 and seismic zone factor, depending upon soil foundation system. Design Horizontal Seismic Coefficient (ah) Seismic coefficient taken for design
Earthquake Zone (Hyderabad) : Zone II Basic Horizontal Seismic Coefficient (a0) : 0.01 Coefficient depends upon soil foundation system (ß) (Hard Soil) : 1.0 Importance Factor (I) : 1.5 Design Value of Horizontal Seismic Coefficient, ah = ß * I * a0 = 0.015
Base Shear Calculations: The Base Shear is given by, Vb = K * C * ah * W Where K = Performance Factor according to structural framing system = 1 C = Coefficient defining the flexibility of structure (depends upon the no. of storey in structure) = 0.75 ah = Design Seismic Coefficient W = Total DL + 25 % of LL
Calculating base shear, Vb = K * C * ah * W = 1 * 0.62 * 0.04 *1947.2 = 482.9152 KN
• Load Distribution: The distribution of base shear along with the height of the building is given by, Qi = Vb * (Wi * hi2) / S (Wi * hi2)
Nodal forces and seismic shear forces at various floor levels
Floor Qi Vi
1 391.7677 482.9151
2 91.1473 91.1473
Possible Load Combinations: (Dead Load + Live Load + Wind Load) * FoS (Dead Load + Live Load) * FoS (Dead Load + Live Load + Earthquake Load) * FoS For 1st case FoS will be 1.5 and for the rest of the case FoS will be 1.2 as per IS – 456
Analysis results: Structure was analyzed in STAAD. SF and BM Diagrams as produced by STAAD
Bending Moment Diagram (isometric view) in STAAD
Shear Force Diagram (isometric view) in STAAD
SF and BM diagrams of beam B1 in STAAD
Deflection Diagrams
Simulation under deflection
Failure zones in the structure
Green – safe zone Yellow – moderate failure zone Red – extreme failure zone
Analysis result data: Shear force, bending moments, axial loads ( for columns) and torsion are calculated for each element.
3. Structural Design
All the members (beams, columns, footings) except slab were designed on a structural design package developed by our own team of students. The package has been tested with real-time problems and gives perfectly reliable results. Slab design was performed on STAAD. Design of beam B1
Alternate design of beam B1
Design of beam B2
Design of ring beam RB3 Ring beam RB3 has been designed manually. All the design calculations were done in a MATLAB script file, which is as follows.
After running script file in MATLAB editor, the outputs are as follows.
Designed cross-section of RB3: Provide section = 700 x 900 mm Provide 6 nos. – 28 mm diameter bars. Design of columns:
design of column C2
Design of column C3 Footing design for columns:
FOODFOOD--COURT FOR INFOSYS SOFTWARE TECHNOLOGY PARK, HyderabadCOURT FOR INFOSYS SOFTWARE TECHNOLOGY PARK, Hyderabad
Footing Design for C4
Design of slab (1st floor)
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