V. IS 1893 2002 Static Seismic
Calculation of base shear and its distribution along the height for equivalent static method in IS 1893 (Part 1) : 2002
Problem
A reinforced concrete frame structure is 4 bays at 4m ea. by 3 bays at 4m ea. in plan. The structure is 3 stories at 3m ea.
The structure is modelled in
STAAD.Pro considering the following:
- Seismic zone factor, Z = 0.36 (ZONE 0.36)
- Importance factor, I = 1 (I 1)
- Response reduction factor, R = 5 (RF 5)
- Soil site condition = Hard (SS 1)
- Structure type is a reinforced concrete frame (ST 1)
The seismic weight for each floor is assumed as 100 kN applied as joint weight to nodes 39, 60, & 80. Seismic Loads as per IS 1893 (Part 1) : 2002 specifications are generated along two horizontal directions global X & global Z. The base shear and its distribution along height reported by STAAD.Pro is verified against hand calculation.
Height = 3 × 3 = 9m
Tax = 0.075h0.75 = 0.075 × (90.75) = 0.39 sec
Taz = 0.075h0.75 = 0.075 × (90.75) = 0.39 sec
[Sa/g]x = [Sa/g]z = 2.5 (As time period < 0.4 sec)
Ahx = (Z/2) × (I/R) × [Sa/g]x = 0.36/2 × 1/5 × 2.5 =0.09
Ahz = (Z/2) × (I/R) × [Sa/g]z = 0.36/2 × 1/5 × 2.5 =0.09
VB = Ah × W
VBx = Ahx × W = 0.09 × (3 × 100) = 27 kN
VBz = Ahz × W = 0.09 × (3 × 100) = 27 kN
STAAD Input
The file C:\Users\Public\Public Documents\STAAD.Pro CONNECT Edition\Samples\ Verification Models\06 Loading\IS 1893\IS 1893 2002 Static Seismic.STD is typically installed with the program.
STAAD SPACE
START JOB INFORMATION
ENGINEER DATE 26-Jun-18
END JOB INFORMATION
INPUT WIDTH 79
*SET STAR 0
UNIT METER KN
JOINT COORDINATES
1 0 0 0; 2 0 3 0; 3 4 3 0; 4 4 0 0; 5 0 0 4; 6 0 3 4; 7 4 3 4; 8 4 0 4;
9 8 3 0; 10 8 0 0; 11 8 3 4; 12 8 0 4; 13 12 3 0; 14 12 0 0; 15 12 3 4;
16 12 0 4; 17 16 3 0; 18 16 0 0; 19 16 3 4; 20 16 0 4; 21 0 0 8; 22 0 3 8;
23 4 3 8; 24 4 0 8; 25 8 3 8; 26 8 0 8; 27 12 3 8; 28 12 0 8; 29 16 3 8;
30 16 0 8; 31 0 0 12; 32 0 3 12; 33 4 3 12; 34 4 0 12; 35 8 3 12; 36 8 0 12;
37 12 3 12; 38 12 0 12; 39 16 3 12; 40 16 0 12; 41 0 6 0; 42 4 6 0; 43 0 6 4;
44 4 6 4; 45 8 6 0; 46 8 6 4; 47 12 6 0; 48 12 6 4; 49 16 6 0; 50 16 6 4;
51 0 6 8; 52 4 6 8; 53 8 6 8; 54 12 6 8; 55 16 6 8; 56 0 6 12; 57 4 6 12;
58 8 6 12; 59 12 6 12; 60 16 6 12; 61 0 9 0; 62 4 9 0; 63 0 9 4; 64 4 9 4;
65 8 9 0; 66 8 9 4; 67 12 9 0; 68 12 9 4; 69 16 9 0; 70 16 9 4;
71 0 9 8; 72 4 9 8; 73 8 9 8; 74 12 9 8; 75 16 9 8; 76 0 9 12;
77 4 9 12; 78 8 9 12; 79 12 9 12; 80 16 9 12;
MEMBER INCIDENCES
1 1 2; 2 2 3; 3 3 4; 4 2 6; 5 3 7; 6 5 6; 7 6 7; 8 7 8; 9 3 9; 10 7 11;
11 9 10; 12 9 11; 13 11 12; 14 9 13; 15 11 15; 16 13 14; 17 13 15; 18 15 16;
19 13 17; 20 15 19; 21 17 18; 22 17 19; 23 19 20; 24 6 22; 25 7 23; 26 11 25;
27 15 27; 28 19 29; 29 21 22; 30 22 23; 31 23 24; 32 23 25; 33 25 26; 34 25 27;
35 27 28; 36 27 29; 37 29 30; 38 22 32; 39 23 33; 40 25 35; 41 27 37; 42 29 39;
43 31 32; 44 32 33; 45 33 34; 46 33 35; 47 35 36; 48 35 37; 49 37 38; 50 37 39;
51 39 40; 52 2 41; 53 3 42; 54 6 43; 55 7 44; 56 9 45; 57 11 46; 58 13 47;
59 15 48; 60 17 49; 61 19 50; 62 22 51; 63 23 52; 64 25 53; 65 27 54; 66 29 55;
67 32 56; 68 33 57; 69 35 58; 70 37 59; 71 39 60; 72 41 42; 73 41 43; 74 42 44;
75 43 44; 76 42 45; 77 44 46; 78 45 46; 79 45 47; 80 46 48; 81 47 48; 82 47 49;
83 48 50; 84 49 50; 85 43 51; 86 44 52; 87 46 53; 88 48 54; 89 50 55; 90 51 52;
91 52 53; 92 53 54; 93 54 55; 94 51 56; 95 52 57; 96 53 58; 97 54 59; 98 55 60;
99 56 57; 100 57 58; 101 58 59; 102 59 60; 103 41 61; 104 42 62; 105 43 63;
106 44 64; 107 45 65; 108 46 66; 109 47 67; 110 48 68; 111 49 69; 112 50 70;
113 51 71; 114 52 72; 115 53 73; 116 54 74; 117 55 75; 118 56 76; 119 57 77;
120 58 78; 121 59 79; 122 60 80; 123 61 62; 124 61 63; 125 62 64; 126 63 64;
127 62 65; 128 64 66; 129 65 66; 130 65 67; 131 66 68; 132 67 68; 133 67 69;
134 68 70; 135 69 70; 136 63 71; 137 64 72; 138 66 73; 139 68 74; 140 70 75;
141 71 72; 142 72 73; 143 73 74; 144 74 75; 145 71 76; 146 72 77; 147 73 78;
148 74 79; 149 75 80; 150 76 77; 151 77 78; 152 78 79; 153 79 80;
DEFINE MATERIAL START
ISOTROPIC CONCRETE
E 2.17185e+07
POISSON 0.17
DENSITY 23.5616
ALPHA 1e-05
DAMP 0.05
TYPE CONCRETE
STRENGTH FCU 27579
END DEFINE MATERIAL
MEMBER PROPERTY AMERICAN
1 TO 153 PRIS YD 0.5 ZD 0.5
CONSTANTS
MATERIAL CONCRETE ALL
SUPPORTS
1 4 5 8 10 12 14 16 18 20 21 24 26 28 30 31 34 36 38 40 FIXED
DEFINE 1893 LOAD
*DEFINE IS1893 2016 LOAD
*ZONE 0.36 RF 5 I 1.2 SS 1 ST 1 DM 0.05 HT 9 DX 16 DZ 12
ZONE 0.36 RF 5 I 1 SS 1 ST 1 DM 0.05
*ZONE 0.36 RF 5 I 1.2 SS 2 ST 1 DM 0.05 HT 9 DX 16 DZ 12
*ZONE 0.36 RF 5 I 1.2 SS 2 ST 1 DM 0.05
*ZONE 0.36 RF 5 I 1.2 SS 3 ST 1 DM 0.05 HT 9 DX 16 DZ 12
*ZONE 0.36 RF 5 I 1.2 SS 3 ST 1 DM 0.05
JOINT WEIGHT
39 60 80 WEIGHT 100
LOAD 1 LOADTYPE Seismic TITLE SS_(+X)
1893 LOAD X 1
LOAD 2 LOADTYPE Seismic TITLE SS_(+Z)
1893 LOAD Z 1
*LOAD 3 LOADTYPE Seismic TITLE SS_(+Y)
*1893 LOAD Y 1
PERFORM ANALYSIS PRINT LOAD DATA
PRINT ANALYSIS RESULTS
FINISH
STAAD Output
********************************************************* * UNITS - KN METE * * TIME PERIOD FOR X 1893 LOADING = 0.38971 SEC * * SA/G PER 1893= 2.500, LOAD FACTOR= 1.000 * * VB PER 1893= 0.0900 X 300.00= 27.00 KN * * * ********************************************************* ********************************************************* * UNITS - KN METE * * TIME PERIOD FOR Z 1893 LOADING = 0.38971 SEC * * SA/G PER 1893= 2.500, LOAD FACTOR= 1.000 * * VB PER 1893= 0.0900 X 300.00= 27.00 KN * * * ********************************************************* JOINT LATERAL TORSIONAL LOAD - 1 LOAD (KN ) MOMENT (KN -METE) FACTOR - 1.000 ----- ------- --------- 39 FX 1.929 MY 0.000 ----------- ----------- TOTAL = 1.929 0.000 AT LEVEL 3.000 METE VB PER 1893 = 27.000 KN 60 FX 7.714 MY 0.000 ----------- ----------- TOTAL = 7.714 0.000 AT LEVEL 6.000 METE VB PER 1893 = 27.000 KN 80 FX 17.357 MY 0.000 ----------- ----------- TOTAL = 17.357 0.000 AT LEVEL 9.000 METE VB PER 1893 = 27.000 KN STAAD SPACE -- PAGE NO. 5 JOINT LATERAL TORSIONAL LOAD - 2 LOAD (KN ) MOMENT (KN -METE) FACTOR - 1.000 ----- ------- --------- 39 FZ 1.929 MY 0.000 ----------- ----------- TOTAL = 1.929 0.000 AT LEVEL 3.000 METE VB PER 1893 = 27.000 KN 60 FZ 7.714 MY 0.000 ----------- ----------- TOTAL = 7.714 0.000 AT LEVEL 6.000 METE VB PER 1893 = 27.000 KN 80 FZ 17.357 MY 0.000 ----------- ----------- TOTAL = 17.357 0.000 AT LEVEL 9.000 METE VB PER 1893 = 27.000 KN