Sir,The model is a steel structure and is analyzed for seismic qualification. One of the criteria checked is displacement.In the model, we see higher joint displacement in nodes 4 & 6.kindly see the model details attached and help us with modifications to reduce the displacement.
STAAD SPACE START JOB INFORMATION ENGINEER DATE 20-Jul-21 END JOB INFORMATION INPUT WIDTH 79 UNIT MMS NEWTON JOINT COORDINATES 1 0 0 0; 2 0 4000 0; 3 0 3550 0; 4 500 3550 0; 5 395 3550 0; 6 395 3550 -275; 7 395 3550 -175; MEMBER INCIDENCES 1 1 3; 2 3 2; 3 3 5; 4 5 4; 5 5 7; 6 7 6; DEFINE MATERIAL START ISOTROPIC STEEL E 205000 POISSON 0.3 DENSITY 7.68195e-005 ALPHA 1.2e-005 DAMP 0.03 TYPE STEEL STRENGTH FY 253.2 FU 407.8 RY 1.5 RT 1.2 END DEFINE MATERIAL MEMBER PROPERTY INDIAN 1 TO 6 TABLE FR ISMC150 CONSTANTS MATERIAL STEEL ALL SUPPORTS 1 FIXED LOAD 1 LOADTYPE Dead TITLE DL SELFWEIGHT Y -1 JOINT LOAD 7 FY -60 LOAD 3 LOADTYPE Live TITLE SL(SSE) JOINT LOAD 7 FX 253 LOAD 5 LOADTYPE Live TITLE SL(SSE)WITH -VE JOINT LOAD 7 FX -253 LOAD 9 LOADTYPE Seismic TITLE EQX(SSE) SELFWEIGHT X 1 SELFWEIGHT Y 1 SELFWEIGHT Z 1 JOINT LOAD 7 FX 253 7 FY 253 7 FZ 253 7 FX 60 7 FY 60 7 FZ 60 SPECTRUM SRSS X 1 ACC DAMP 0 LIN MIS 0 20 1193.6; 4 1193.6; 2.85714 1422.3; 2.5 1617.9; 2.22222 1945.8; 2 2181; 1.66667 2367.2; 1.53846 2513.4; 1.42857 2807.3; 1.25 2962.9; 1.17647 3193.4; 1.05263 3375.2; 0.869565 3375.2; 0.8 3487.7; 0.740741 3788.5; 0.714286 3788.5; 0.666667 3937.6; 0.645161 4265.7; 0.625 4432; 0.588235 4446.4; 0.555556 4674; 0.540541 4901.6; 0.487805 5927.8; 0.465116 5927.8; 0.444444 6193.5; 0.425532 6893.2; 0.416667 7599.6; 0.4 8312.6; 0.294118 8312.6; 0.285714 7493.5; 0.28169 7185.4; 0.232558 6855; 0.227273 7209.7; 0.212766 7242.9; 0.206186 7611.2; 0.20202 7701.7; 0.19802 7727.5; 0.192308 7938.9; 0.190476 8289.1; 0.185185 8800.3; 0.181818 9054.8; 0.18018 9208.7; 0.178571 9235.4; 0.131579 9235.4; 0.12987 9145.6; 0.128205 8932.1; 0.127389 8875.1; 0.125786 9058.5; 0.125 9090.6; 0.0925926 9090.6; 0.0909091 8988.7; 0.0892857 8742; 0.0877193 8677.2; 0.0869565 8552.8; 0.0865801 8520; 0.0858369 8310.4; 0.0854701 8226.8; 0.0851064 8185.5; 0.0840336 7979.7; 0.08 8028.7; 0.0591716 8028.7; 0.0588235 7505.1; 0.058651 7287.5; 0.0584795 7158.5; 0.058309 7053.6; 0.0571429 6723.1; 0.0560224 6460.8; 0.0554017 6298.8; 0.0550964 5902.6; 0.0549451 5732.7; 0.0544959 5376; 0.0526316 5184.1; 0.052356 4879.1; 0.0522193 4747.8; 0.0520833 4659.1; 0.0508906 4627; 0.0502513 4422.2; 0.0496278 4354.4; 0.0486618 4065.1; 0.0465116 3813.5; 0.0433839 3274.8; 0.04329 3216.5; 0.0357782 2795.6; 0.0322061 2795.6; 0.030303 2624; LOAD 10 LOADTYPE Seismic TITLE EQY(SSE) SPECTRUM SRSS Y 0.67 ACC DAMP 0.05 LIN MIS 0 20 797.5; 4 797.5; 2.85714 948.8; 2.5 1078.2; 2.22222 1291.6; 2 1444.2; 1.66667 1568.4; 1.53846 1666.5; 1.42857 1878.8; 1.25 1960.3; 1.17647 2118.6; 1.05263 2272.7; 0.869565 2272.7; 0.8 2331.9; 0.769231 2391.1; 0.740741 2521.8; 0.714286 2521.8; 0.666667 2542; 0.645161 2744.7; 0.625 2849.3; 0.588235 2849.8; 0.555556 2969.2; 0.540541 3088.5; 0.487805 4043.3; 0.47619 4256.4; 0.454545 4469.6; 0.425532 4903.1; 0.416667 5521.8; 0.4 6470.3; 0.294118 6470.3; 0.28169 6284.8; 0.25974 6950; 0.253165 7038.8; 0.243902 7282.6; 0.238095 7376.2; 0.212766 7501.6; 0.206186 7857.8; 0.204082 8091.4; 0.20202 8550.9; 0.19802 9002.4; 0.145985 9002.4; 0.133333 8867.3; 0.131579 9460.2; 0.12987 9611.8; 0.129032 9799.2; 0.128205 10173.9; 0.127389 10190.2; 0.0938967 10190.2; 0.0930233 10112.9; 0.0913242 9828.1; 0.0843882 8609; 0.0833333 8477.5; 0.0826446 8455; 0.0809717 8455; 0.0803213 8173.3; 0.08 8148; 0.0796813 8097.4; 0.0790514 7849.2; 0.077821 7437.3; 0.0775194 7371.8; 0.0763359 6818; 0.0757576 6617.4; 0.0740741 6156.8; 0.0735294 5836; 0.0732601 5704.6; 0.0729927 5630.8; 0.0727273 5589.3; 0.0719424 5581.4; 0.0711744 5581.4; 0.0696864 5485; 0.0687285 5485; 0.0682594 5389.3; 0.0657895 5365.9; 0.0641026 4983.8; 0.0591716 4610.1; 0.058651 4104.1; 0.0584795 3988.1; 0.058309 3917.2; 0.0581395 3868; 0.0555556 3627; 0.0546448 3627; 0.0508906 3583.2; 0.0501253 3458.5; 0.0496278 3458.5; 0.0493827 3457.7; 0.0486618 3457.7; 0.0465116 3421.6; 0.0462963 3340.2; 0.0460829 3299.4; 0.0458716 3218; 0.0452489 3147.9; 0.0433839 2743; 0.04329 2659.8; 0.030303 2265.9; LOAD 11 LOADTYPE Seismic TITLE EQZ(SSE) SPECTRUM SRSS Z 1 ACC DAMP 0 LIN MIS 0 20 1197.4; 4 1197.4; 2.85714 1423.8; 2.5 1619.7; 2.22222 1946.8; 2 2184.5; 1.66667 2362; 1.53846 2514.6; 1.42857 2839.1; 1.25 2964.9; 1.17647 3207.6; 1.05263 3414.1; 0.869565 3414.1; 0.8 3536.9; 0.740741 3861.6; 0.714286 3861.6; 0.666667 3972; 0.645161 4218; 0.625 4315.9; 0.588235 4387.7; 0.555556 4637.7; 0.540541 4887.6; 0.487805 5969; 0.454545 6031.5; 0.425532 7171.6; 0.416667 7883.4; 0.4 8547.1; 0.377358 8579.8; 0.28169 8579.8; 0.277778 8469.1; 0.266667 8320.4; 0.263158 8308.6; 0.25974 8369; 0.253165 8429.4; 0.204082 8432.1; 0.20202 8597.5; 0.19802 8741.4; 0.192308 8865; 0.190476 9090.3; 0.188679 9202.9; 0.185185 9304.4; 0.181818 9447.1; 0.18018 9574.7; 0.178571 9631.1; 0.148148 9698.9; 0.147059 9843.6; 0.145985 9900.4; 0.137931 9900.4; 0.136054 9960.5; 0.134228 10365; 0.133333 10603.1; 0.131579 10841.2; 0.129032 11614.9; 0.128205 12104.5; 0.127389 12144.8; 0.125786 12524.2; 0.0930233 12524.2; 0.0925926 12504.7; 0.0917431 12308; 0.0913242 12242.4; 0.0884956 11456.5; 0.0881057 11387.2; 0.0865801 11304.8; 0.0809717 11304.8; 0.0803213 11108.6; 0.08 11059.9; 0.0796813 10962.5; 0.0790514 10579.6; 0.0784314 10257; 0.077821 10010.4; 0.0775194 9921.8; 0.0760456 8986; 0.0757576 8828.6; 0.075188 8656.3; 0.0740741 8472.3; 0.0735294 8142.3; 0.0724638 7722.4; 0.0722022 7647.7; 0.0714286 7529.3; 0.0706714 7523.2; 0.0701754 7523.2; 0.0687285 7514.2; 0.0684932 7410.9; 0.0680272 7311.7; 0.0675676 7311.7; 0.0657895 7259.1; 0.0643087 6630.1; 0.0641026 6575.8; 0.0628931 6131.9; 0.0591716 5937.6; 0.0588235 5312.7; 0.058651 5055.7; 0.0584795 4909.6; 0.058309 4801.3; 0.0554017 4377.1; 0.0544959 4115.3; 0.0526316 4036.5; 0.0520833 3866.1; 0.0508906 3847.4; 0.0502513 3682.8; 0.0433839 3196.9; 0.0431965 3144.1; 0.030303 2692.3; LOAD COMB 20 LC1(SSE) 1 1.0 9 1.0 3 1.0 LOAD COMB 21 LC2(SSE) 1 1.0 10 1.0 3 1.0 LOAD COMB 22 LC3(SSE) 1 1.0 11 1.0 3 1.0 LOAD COMB SRSS 23 LC4(SSE) -1 1.0 9 1.0 10 1.0 11 1.0 -3 1.0 1 LOAD COMB 24 LC1(SSE WITH -VE SL) 1 1.0 5 1.0 9 1.0 LOAD COMB 25 LC2(SSE WITH -VE SL) 1 1.0 5 1.0 10 1.0 LOAD COMB 26 LC3(SSE WITH -VE SL) 1 1.0 5 1.0 11 1.0 LOAD COMB SRSS 27 LC4(SSE WITH -VE SL) -1 1.0 -5 1.0 9 1.0 10 1.0 11 1.0 1 PERFORM ANALYSIS PRINT STATICS CHECK FINISH
As there is high lateral loads displacement is expected. You may try with some higher sections to reduce displacement.
Sir,
Changing the section is not possible as it is an existing structure.
Whether We can do some strengthening to qualify.
Sir , Thank you .
S we are using site specific spectra to DBE level.
One clarification : For MCE level whether this I/R is applicable?
No, for MCE level you can't use I/R. For design purpose, DBE level should e considered.
In this case, we need to qualify the structure for both DBE and MCE level with site specific spectra.
The structure I value is 2 & R value is 4. I/R = 0.5
For DBE level:
Direction factor used is 0.5 for X & Z direction and for Y direction 0.33 (2/3 of 0.5) used in the analysis.
For MCE level:
Direction factor used is 1 for X & Z direction and for Y direction 0.67 (2/3 of 1) used in the analysis.
Kindly clarify whether this values used in the analysis is ok .
Yes, your understanding is correct.
For DBE level,
X and Z direction factor will be 0.5 and in Y direction 0.33
For MCE level
X and Z direction factor will be 1 and in Y direction 0.67.
thank you