Vertical component of seismic load - NBCC

Question

Dear All, 
 
 I am trying to consider vertical component of seismic load using National building code of Canada NBCC. I assume 70% of acceleration is vertical direction (see below), but I am getting errors. I would appreciate if you tell me where is the error and if there are example of using Staad to calculate seismic load using NBCC. Thanks a lot 
 
 STAAD SPACE START JOB INFORMATION ENGINEER DATE 30-Oct-21 END JOB INFORMATION INPUT WIDTH 79 UNIT METER KN JOINT COORDINATES 1 0 1.1 0; 2 6 8.175 0; 4 6 1.1 0; 6 0 8.175 0; 7 0 6.375 0; 9 6 6.975 0; 10 6 8.775 0; 11 0 8.775 0; 12 6 5.175 0; 13 0 5.175 0; 14 0 6.975 0; 16 6 4.375 0; 17 6 3.175 0; 18 4.05001 6.975 0; 19 0 1.1 6; 20 6 8.175 6; 21 6 6.375 6; 22 6 1.1 6; 23 6 4.175 6; 24 0 8.175 6; 25 0 6.375 6; 26 0 4.175 6; 27 6 6.975 6; 28 6 8.775 6; 29 0 8.775 6; 30 6 5.175 6; 31 0 5.175 6; 32 0 6.975 6; 33 6 2.175 6; 34 6 4.375 6; 35 6 3.175 6; 36 3 5.175 6; 37 3 8.775 6; 38 4.05001 6.975 6; 39 0 8.175 9; 40 0 6.375 9; 41 6 8.175 9; 42 6 6.375 9; 43 6 4.175 9; 44 0 4.175 9; 45 0 8.175 12; 46 0 6.375 12; 47 6 8.175 12; 48 6 6.375 12; 49 0 1.1 12; 50 6 1.1 12; 51 0 8.775 12; 52 6 8.775 12; 53 6 5.175 12; 54 0 5.175 12; 55 0 6.975 12; 56 6 6.975 12; 57 0 7.19 12; 58 0 4.175 12; 59 6 4.175 12; 60 3 5.175 12; 61 3 8.775 12; 679 3 5.175 9; 680 3 8.775 9; MEMBER INCIDENCES 1452 49 58; 1453 47 56; 1454 50 59; 1455 45 57; 1456 47 52; 1457 45 51; 1458 53 48; 1459 54 46; 1460 55 46; 1461 56 48; 1462 51 61; 1463 55 56; 1464 54 60; 1465 57 55; 1468 58 54; 1469 59 53; 1470 24 39; 1471 25 40; 1472 20 41; 1473 21 42; 1474 23 43; 1475 39 45; 1476 40 46; 1477 41 47; 1478 42 48; 1479 43 59; 1480 26 44; 1481 44 58; 1482 19 44; 1483 49 44; 1484 26 40; 1485 58 40; 1486 25 39; 1487 46 39; 1488 22 43; 1489 50 43; 1490 23 42; 1491 59 42; 1492 21 41; 1493 48 41; 1494 19 26; 1495 20 27; 1496 22 33; 1497 24 32; 1498 20 28; 1499 24 29; 1500 30 21; 1501 31 25; 1502 32 25; 1503 27 21; 1505 26 31; 1506 23 34; 1507 29 37; 1508 32 38; 1509 31 36; 1510 33 35; 1511 1 13; 1512 2 9; 1513 4 17; 1514 6 14; 1515 2 10; 1516 6 11; 1517 12 9; 1518 13 7; 1519 14 7; 1522 16 17; 1523 11 10; 1524 14 18; 1525 13 12; 1527 6 24; 1528 7 25; 1529 13 31; 1530 2 20; 1531 9 27; 1532 12 30; 1533 16 12; 1534 34 30; 1535 16 34; 1537 35 23; 1538 17 35; 1559 36 30; 1560 60 53; 1561 36 679; 1562 31 679; 1563 30 679; 1564 37 28; 1565 61 52; 1566 37 680; 1567 29 680; 1568 28 680; 1569 38 27; 1570 18 9; 1571 18 38; 1575 679 60; 1576 679 53; 1577 679 54; 1578 680 61; 1579 680 52; 1580 680 51; DEFINE MATERIAL START ISOTROPIC STEEL E 2.05e+08 POISSON 0.3 DENSITY 76.8195 ALPHA 1.2e-05 DAMP 0.03 G 7.88462e+07 TYPE STEEL STRENGTH RY 1.5 RT 1.2 END DEFINE MATERIAL MEMBER PROPERTY CANADIAN 1452 TO 1461 1465 1468 1469 1494 TO 1503 1505 1506 1510 TO 1519 1522 1533 - 1534 1537 TABLE ST W310X86 1462 1463 1507 1508 1523 1524 1564 1565 1569 1570 TABLE ST W310X60 1470 TO 1481 1527 TO 1532 1535 1538 1571 TABLE ST W250X33 1484 TO 1487 1490 TO 1493 TABLE T W250X49 1464 1509 1525 1559 1560 TABLE ST W410X85 1561 1566 1575 1578 TABLE ST W200X36 1562 1563 1567 1568 1576 1577 1579 1580 TABLE T W200X36 1482 1483 1488 1489 TABLE T W310X79 CONSTANTS BETA 90 MEMB 1482 TO 1493 MATERIAL STEEL ALL SUPPORTS 1 4 19 22 49 50 PINNED MEMBER RELEASE 1470 TO 1474 1480 1482 TO 1493 1527 TO 1532 1535 1538 1561 TO 1563 - 1566 TO 1568 1571 1576 1577 1579 1580 START MY MZ 1475 1476 1478 1479 1481 TO 1493 1527 TO 1532 1535 1538 1562 1563 1567 1568 - 1571 1575 TO 1580 END MY MZ 1477 END MY MZ CUT OFF MODE SHAPE 100 ******************* For seismic load DEFINE REFERENCE LOADS LOAD R1 LOADTYPE Mass TITLE MASS - FOR SEISMIC CASE * Own weight of steel structures SELFWEIGHT X 1.1 SELFWEIGHT Y 1.1 SELFWEIGHT Z 1.1 END DEFINE REFERENCE LOADS ******************************** DEFINE NRC 2010 LOAD SA1 1.14 SA2 0.66 SA3 0.35 SA4 0.15 I 1.3 SCL 3 MVX 1.2 MVZ 1.2 RDX 2 RDZ 2 - ROX 1.5 ROZ 1.5 PX 0.75 PZ 0.19 FA 1 FV 1 STX 1 STZ 3 MD 1 ************* Seismic load ************************** LOAD 1 LOADTYPE Seismic-H TITLE SEISMIC_X+ NRC LOAD X 1 LOAD 2 LOADTYPE Seismic-H TITLE SEISMIC_Z+ NRC LOAD Z 1 LOAD 3 LOADTYPE Seismic-V TITLE SEISMIC +Y NRC LOAD Y 0.66666 PERFORM ANALYSIS PARAMETER 1 CODE CANADIAN ************* FYLD 345000 MEMB 1482 TO 1493 1562 1563 1567 1568 1576 1577 1579 1580 ************* FYLD 345000 MEMB 1452 TO 1465 1468 TO 1481 1494 TO 1503 1505 TO 1519 1522 - 1523 TO 1525 1527 TO 1535 1537 1538 1559 TO 1561 1564 TO 1566 1569 TO 1571 - 1575 1578 *********************************************************************** PERFORM ANALYSIS FINISH

Suvadeep Acharjee · Answer

The load generation facility has been developed to generate equivalent static seismic loads per NBCC/NRC 2010 along horizontal directions only. However in your model Load Case 3 attempts to generate loads along vertical direction hence the error. You can manually generate vertical component of seismic load in Load Case 3 in Y direction as nodal joint loads instead of NRC LOAD to avoid the error. Amongst horizontal directions (i.e. X & Z) check which direction base shear is more (Z direction in this model) then use PRINT LOAD DATA command to print the joint loading data along that direction in output file. Copy the loading data in excel and apply factor 0.66666 and then apply as joint loads in Load Case 3. NRC 2010.STD

Suvadeep Acharjee · Answer

Yes your understanding is correct. The program is not capable of generating equivalent static seismic load along vertical direction for NBCC/NRC 2010 codes. For response spectrum loading program expects user to provide time-acceleration (spectrum type = acceleration) or time-displacement (spectrum type = displacement) pairs. In the data you have provided its not clear what the unit of function S(T) is and you need to check whether data is for acceleration spectra or displacement spectra. If it is for acceleration spectra then just enter the time-acceleration pairs inside the response spectrum loading dialog box. Factors for the input spectrum to be applied in X, Y, & Z directions. In picture you attached direction factor is used as 1.0 for vertical Y direction so if you want to consider 66.666% in vertical direction you should change it to 0.66666. I f the acceleration data available for response spectrum is in terms of g's (i.e. acceleration due to gravity) then one needs to account for it. In STAAD we have SCALE parameter which is the factor by which the spectral data will be multiplied for factoring g's to length/sec2 units. This SCALE parameter should be input according to current unit system i.e. it may be 9.81 in m/s2 unit system or 32.2 ft/s2 unit system.