Problem. A five-storey shear wall split into two piers by door openings and joined by a coupling beam at every floor is solved separately with MindFEM and with ETABS. The shells carry pier (PIER) and coupling beam (SPANDREL) labels, and both programs sum the section forces of every label. The axial force, shear and moment of the piers at every storey and the end shear and moment of the coupling beams are compared.
Reference document. The reference is the same wall modelled in ETABS 20.1.0 with its own objects. The labels are given with the pier and spandrel assignments of ETABS, and the forces are read from its pier and spandrel output.
Numerical model. The wall is 7.5 m wide with five storeys of 3 m; P1 and P2 are each 3 m wide, and above the 1.5 m wide, 2 m high door opening between them a 1 m deep coupling beam joins them at every floor (S1 to S5). The thickness is 0.30 m, the concrete C30/37, the base is fixed and the mesh is made of 0.25 × 0.25 m quadrilateral elements.
Five-storey coupled shear wall
Independent calculation. ETABS 20.1.0, the same structure modelled with ETABS's own objects
42-row table · largest deviation 3.98%
| Quantity | Reference | Computed | Deviation |
|---|---|---|---|
| EX: P1, bottom of storey 1, N [kN] | 486.318 | 486.364 | 0.0093% |
| EX: P1, bottom of storey 1, V2 [kN] | 150 | 150 | < 0.001% |
| EX: P1, bottom of storey 1, M3 [kNm] | 555.784 | 555.681 | 0.0184% |
| EX: P1, bottom of storey 2, N [kN] | 388.001 | 387.994 | 0.0018% |
| EX: P1, bottom of storey 2, V2 [kN] | 140 | 140 | < 0.001% |
| EX: P1, bottom of storey 2, M3 [kNm] | 326.997 | 327.014 | 0.0049% |
| EX: P1, bottom of storey 3, N [kN] | 262.859 | 262.819 | 0.0151% |
| EX: P1, bottom of storey 3, V2 [kN] | 120 | 120 | < 0.001% |
| EX: P1, bottom of storey 3, M3 [kNm] | 188.568 | 188.657 | 0.0473% |
| EX: P1, bottom of storey 4, N [kN] | 146.614 | 146.564 | 0.0341% |
| EX: P1, bottom of storey 4, V2 [kN] | 90 | 90 | < 0.001% |
| EX: P1, bottom of storey 4, M3 [kNm] | 90.1178 | 90.2302 | 0.125% |
| EX: P1, bottom of storey 5, N [kN] | 53.6607 | 53.617 | 0.0815% |
| EX: P1, bottom of storey 5, V2 [kN] | 50 | 50 | < 0.001% |
| EX: P1, bottom of storey 5, M3 [kNm] | 29.2634 | 29.3618 | 0.336% |
| EX: S1, left end, V2 [kN] | 98.3172 | 98.3698 | 0.0535% |
| EX: S1, left end, M3 [kNm] | 72.9315 | 72.9709 | 0.0541% |
| EX: S2, left end, V2 [kN] | 125.142 | 125.175 | 0.0259% |
| EX: S2, left end, M3 [kNm] | 92.2439 | 92.2683 | 0.0264% |
| EX: S3, left end, V2 [kN] | 116.244 | 116.255 | 0.0089% |
| EX: S3, left end, M3 [kNm] | 84.7639 | 84.7717 | 0.0091% |
| EX: S4, left end, V2 [kN] | 92.9536 | 92.9474 | 0.0067% |
| EX: S4, left end, M3 [kNm] | 66.4894 | 66.4847 | 0.0070% |
| EX: S5, left end, V2 [kN] | 53.6607 | 53.617 | 0.0815% |
| EX: S5, left end, M3 [kNm] | 36.2133 | 36.1805 | 0.0906% |
| EX: P2, bottom of storey 1, N [kN] | -486.318 | -486.364 | 0.0093% |
| EX: P2, bottom of storey 1, V2 [kN] | 150 | 150 | < 0.001% |
| EX: P2, bottom of storey 1, M3 [kNm] | 555.784 | 555.681 | 0.0184% |
| G: P1, bottom of storey 1, N [kN] | -658.556 | -658.556 | < 0.001% |
| G: P1, bottom of storey 1, M3 [kNm] | -21.5616 | -22.4194 | 3.98% |
| G: P2, bottom of storey 1, N [kN] | -658.556 | -658.556 | < 0.001% |
| G: P2, bottom of storey 1, M3 [kNm] | 21.5616 | 22.4194 | 3.98% |
| G: P1, bottom of storey 3, N [kN] | -395.133 | -395.133 | < 0.001% |
| G: S1, left end, V2 [kN] | -5.51624 | -5.51624 | < 0.001% |
| G: S1, left end, M3 [kNm] | -2.29294 | -2.34745 | 2.38% |
| G + EX: P1, bottom of storey 1, N [kN] | -172.237 | -172.192 | 0.0264% |
| G + EX: P1, bottom of storey 1, M3 [kNm] | 534.222 | 533.262 | 0.180% |
| G + EX: P2, bottom of storey 1, N [kN] | -1,144.87 | -1,144.92 | 0.0040% |
| G + EX: P2, bottom of storey 1, M3 [kNm] | 577.345 | 578.101 | 0.131% |
| G + EX: P1, bottom of storey 3, N [kN] | -132.275 | -132.314 | 0.0300% |
| G + EX: S1, left end, V2 [kN] | 92.801 | 92.8536 | 0.0567% |
| G + EX: S1, left end, M3 [kNm] | 70.6385 | 70.6235 | 0.0213% |
Elevation of the wall: piers P1 and P2, the door openings in dashed lines, and the coupling beams S1 to S5 above the openings at every floor. Dimensions are in metres.
Note. G is the self weight with 20 kN/m on the piers at every floor, EX a lateral load at the floors rising from 20 to 100 kN. The values are the force on the positive face of the section, N is positive in tension, and the two programs use the same sign convention. The bottom section of a pier is just above the floor, the left end of a coupling beam is the section where it joins P1. The top sections are left out. That section passes through the corner node where the coupling beam joins the pier, which is also the corner of the door opening of the storey above. There the shear force agrees within 1 per cent and the axial force differs by 1 to 3 per cent in the first three storeys, while the moment approaches zero higher up and its percentage difference grows without meaning. The difference comes from how the end force of the coupling beam is shared among its end nodes; its total at the end is the same in both programs.
Model files
The ETABS model that produced the results in the table can be downloaded. It opens in ETABS 20
and later with File > Import > ETABS .e2k File.