V. IS 1893 2015 Static Seismic
Calculate the design lateral force at each node in each global direction by the equivalent static seismic method per the IS 1893 (Part 4) 2015 specification.
Details
The loads at each node are taken as the same in each global direction (i.e., Wxi = Wzi = Wyi). Loads at nodes 2, 8, and 14 are 15 kN ea. Loads at nodes 3, 4, 7, 9, 12, and 13 are 10 kN ea.
Sections used for all members: ISMB 450
Materials used: steel
The structure is modelled in STAAD.Pro considering the following:- Seismic zone factor, Z = 0.36 (ZONE 0.36)
- Importance factor, I = 1.0 (I 1.0)
- Response reduction factor, R = 5 (RF 5)
- Soil site condition = Hard (SS 1)
- Structure type is a category 4 (ST 4)
- 2% Damping (DM 0.02)
Validation
Seismic Load
Seismic Loads as per IS 1893 (Part 4): 2015 specifications are generated along two horizontal directions, global X & global Z and also along vertical direction, global Y.
Time period in X direction: Tx = 0.09734 sec.
Time period in Z direction: Tz = 0.51406 sec.
Time Period, T, is calculated by the Rayleigh Method
As per Table 15 of IS 1893 (Part 4): 2015
Damping Factor (DF) for 2% damping = 1.4
From figure 1 of IS 1893 (Part 4): 2015, for Hard Soil sites for (0 second <T<0.1 second)
Spectral acceleration coefficient value () in X, Z, and Y directions for 2% damping:
From figure 1 of IS 1893 (Part 4): 2015, for Hard Soil sites for (0.4 second <T<10 second)
As per clause 10.2 of IS 1893 (Part 4): 2015
As per clause 7.3.2 of IS 1893 (Part 4): 2015
Node | W (kN) | Design lateral force in X direction Qx = Wx × Ah_x |
Design lateral force in Z direction Qz = Wz × Ah_z |
Design force in Y direction Qy = Wy × Ah_y |
---|---|---|---|---|
2 | 15 | (15 × 0.124) = 1.860 | (15 × 0.098) = 1.471 | (15 × 0.083) = 1.240 |
3 | 10 | (10 × 0.124) = 1.240 | (10 × 0.098) = 0.980 | (10 × 0.083) = 0.827 |
4 | 10 | (10 × 0.124) = 1.240 | (10 × 0.098) = 0.980 | (10 × 0.083) = 0.827 |
7 | 10 | (10 × 0.124) = 1.240 | (10 × 0.098) = 0.980 | (10 × 0.083) = 0.827 |
8 | 15 | (15 × 0.124) = 1.860 | (15 × 0.098) = 1.471 | (15 × 0.083) = 1.240 |
9 | 10 | (10 × 0.124) = 1.240 | (10 × 0.098) = 0.980 | (10 × 0.083) = 0.827 |
12 | 10 | (10 × 0.124) = 1.240 | (10 × 0.098) = 0.980 | (10 × 0.083) = 0.827 |
13 | 10 | (10 × 0.124) = 1.240 | (10 × 0.098) = 0.980 | (10 × 0.083) = 0.827 |
14 | 15 | (15 × 0.124) = 1.860 | (15 × 0.098) = 1.471 | (15 × 0.083) = 1.240 |
Results
Result Type | Calculations | STAAD.Pro | Difference | Comments |
---|---|---|---|---|
3.444 | 3.444 | none | ||
Ah_x | 0.124 | 0.124 | none | |
2.723 | 2.723 | none | ||
Ah_z | 0.098 | 0.098 | none | |
2.296 | 2.296 | none | ||
Ah_y | 0.083 | 0.083 | none | |
Qx at Nodes 2,8,14 (kN) | 1.860 | 1.860 | none | |
Qx at Nodes 3,4,7, 9,12, 13 (kN) | 1.240 | 1.240 | none | |
Qz at Nodes 2,8,14 (kN) | 1.471 | 1.471 | none | |
Qz at Nodes 3,4,7, 9,12, 13 (kN) | 0.980 | 0.980 | none | |
Qy at Nodes 2,8,14 (kN) | 1.240 | 1.240 | none | |
Qy at Nodes 3,4,7, 9,12, 13 (kN) | 0.827 | 0.827 | none |
STAAD.Pro Input
The file C:\Users\Public\Public Documents\STAAD.Pro 2023\Samples \Verification Models\06 Loading\IS 1893\IS 1893 2015 Static Seismic.std is typically installed with the program.
STAAD SPACE
START JOB INFORMATION
ENGINEER DATE 25-Mar-20
END JOB INFORMATION
INPUT WIDTH 79
UNIT METER KN
JOINT COORDINATES
1 0 0 0; 2 0 4 0; 3 3 7 0; 4 6 4 0; 5 6 0 0; 6 0 0 5; 7 0 4 5; 8 3 7 5;
9 6 4 5; 10 6 0 5; 11 0 0 10; 12 0 4 10; 13 3 7 10; 14 6 4 10; 15 6 0 10;
MEMBER INCIDENCES
2 1 2; 3 2 3; 4 3 4; 5 4 5; 7 6 7; 8 7 8; 9 8 9; 10 9 10; 11 2 7; 12 8 3;
13 4 9; 14 2 4; 15 7 9; 16 11 12; 17 12 13; 18 13 14; 19 14 15; 20 12 14;
21 7 12; 22 9 14; 23 8 13;
DEFINE MATERIAL START
ISOTROPIC STEEL
E 2.05e+08
POISSON 0.3
DENSITY 76.8195
ALPHA 1.2e-05
DAMP 0.03
TYPE STEEL
STRENGTH RY 1.5 RT 1.2
END DEFINE MATERIAL
MEMBER PROPERTY INDIAN
2 TO 5 7 TO 23 TABLE ST ISMB450
CONSTANTS
MATERIAL STEEL ALL
SUPPORTS
1 5 6 10 11 15 FIXED
DEFINE REFERENCE LOADS
LOAD R1 LOADTYPE Mass TITLE REF LOAD CASE 1
JOINT LOAD
2 8 14 FX 15 FY -15 FZ 15
3 4 7 9 12 13 FX 10 FY -10 FZ 10
END DEFINE REFERENCE LOADS
FLOOR DIAPHRAGM
DIA 1 TYPE RIG HEI 4
DIA 2 TYPE RIG HEI 7
DEFINE IS1893 2015 LOAD PART4
ZONE 0.36 RF 5 I 1 SS 1 ST 4 DM 0.02
LOAD 1 LOADTYPE None TITLE STATIC_X
1893 LOAD X 1
LOAD 2 LOADTYPE None TITLE STATIC_Z
1893 LOAD Z 1
LOAD 3 LOADTYPE None TITLE STATIC_Y
1893 LOAD Y 1
PERFORM ANALYSIS PRINT LOAD DATA
PRINT ANALYSIS RESULTS
FINISH
STAAD.Pro Output
LOADING 1 LOADTYPE NONE TITLE STATIC_X ----------- LOADING 2 LOADTYPE NONE TITLE STATIC_Z ----------- LOADING 3 LOADTYPE NONE TITLE STATIC_Y ----------- **WARNING: IF THIS UBC/IBC ANALYSIS HAS TENSION/COMPRESSION OR REPEAT LOAD OR RE-ANALYSIS OR SELECT OPTIMIZE, THEN EACH UBC/IBC CASE SHOULD BE FOLLOWED BY PERFORM ANALYSIS & CHANGE. BASE SHEAR AND TIME PERIOD IN X ********************************************************* * UNITS - KN METE * * TIME PERIOD FOR X 1893 LOADING = 0.09734 SEC * * SA/G PER 1893= 3.444, LOAD FACTOR= 1.000 * * AH PER 1893= 0.124 WEIGHT= 105.00 KN * ********************************************************* ***NOTE: For Industrial Structures, Static Seismic Load is applied per node. Use command: PRINT LOAD DATA to view the applied load at each node. Ref. Cl.10.2 BASE SHEAR AND TIME PERIOD IN Z ********************************************************* * UNITS - KN METE * * TIME PERIOD FOR Z 1893 LOADING = 0.51406 SEC * * SA/G PER 1893= 2.723, LOAD FACTOR= 1.000 * * AH PER 1893= 0.098 WEIGHT= 105.00 KN * ********************************************************* ***NOTE: For Industrial Structures, Static Seismic Load is applied per node. Use command: PRINT LOAD DATA to view the applied load at each node. Ref. Cl.10.2 BASE SHEAR AND TIME PERIOD IN Y ********************************************************* * UNITS - KN METE * * SA/G FOR Y-DIR CALCULATED AS PER CL.10.2 * * FOR INDUSTRIAL STRUCTURES * * SA/G PER 1893= 2.296, LOAD FACTOR= 1.000 * * AH PER 1893= 0.083 WEIGHT= 105.00 KN * ********************************************************* ***NOTE: For Industrial Structures, Static Seismic Load is applied per node. Use command: PRINT LOAD DATA to view the applied load at each node. Ref. Cl.10.2 STAAD SPACE -- PAGE NO. 5 JOINT LATERAL TORSIONAL LOAD - 1 LOAD (KN ) MOMENT (KN -METE) FACTOR - 1.000 ----- ------- --------- 2 FX 1.860 MY 0.000 4 FX 1.240 MY 0.000 7 FX 1.240 MY 0.000 9 FX 1.240 MY 0.000 12 FX 1.240 MY 0.000 14 FX 1.860 MY 0.000 ----------- ----------- TOTAL = 8.679 0.000 AT LEVEL 4.000 METE 3 FX 1.240 MY 0.000 8 FX 1.860 MY 0.000 13 FX 1.240 MY 0.000 ----------- ----------- TOTAL = 4.340 0.000 AT LEVEL 7.000 METE JOINT LATERAL TORSIONAL LOAD - 2 LOAD (KN ) MOMENT (KN -METE) FACTOR - 1.000 ----- ------- --------- 2 FZ 1.471 MY 0.000 4 FZ 0.980 MY 0.000 7 FZ 0.980 MY 0.000 9 FZ 0.980 MY 0.000 12 FZ 0.980 MY 0.000 14 FZ 1.471 MY 0.000 ----------- ----------- TOTAL = 6.863 0.000 AT LEVEL 4.000 METE 3 FZ 0.980 MY 0.000 8 FZ 1.471 MY 0.000 13 FZ 0.980 MY 0.000 ----------- ----------- TOTAL = 3.431 0.000 AT LEVEL 7.000 METE JOINT LATERAL TORSIONAL LOAD - 3 LOAD (KN ) MOMENT (KN -METE) FACTOR - 1.000 ----- ------- --------- 2 FY 1.240 MY 0.000 4 FY 0.827 MY 0.000 7 FY 0.827 MY 0.000 9 FY 0.827 MY 0.000 12 FY 0.827 MY 0.000 14 FY 1.240 MY 0.000 STAAD SPACE -- PAGE NO. 6 ----------- ----------- TOTAL = 5.786 0.000 AT LEVEL 4.000 METE 3 FY 0.827 MY 0.000 8 FY 1.240 MY 0.000 13 FY 0.827 MY 0.000 ----------- ----------- TOTAL = 2.893 0.000 AT LEVEL 7.000 METE