Problem. In a steel hangar of nine portal frames, 30 m in span and 48 m long, bridge cranes travel on continuous crane girders resting on column brackets on both sides. The travel of one and of two cranes along the girder is solved separately with MindFEM and with SAP2000, and the largest and smallest values of quantities in the crane girder, the bracket and the column bases are compared. Two cases of the cranes braking at given positions and the self weight are compared as static cases.
Reference document. The reference is the same hangar modelled in SAP2000 27.1.0 with its own objects. The crane envelopes are read from its moving load analysis, the braking cases from static load cases.
Numerical model. The columns are HEB 500, the rafters IPE 600, the brackets HEB 300 and the crane girders HEB 400; the column bases are fixed and the end bays carry wall and roof bracing. The crane girders are at 7.5 m and the rails 29 m apart; nodes sit only where members meet, and the crane girder is a single frame element in every span.
Steel crane hangar, moving crane load and braking
Independent calculation. SAP2000 27.1.0, the same hangar modelled with SAP2000's own objects and its moving load analysis
58-row table · largest deviation 1.09%
| Quantity | Reference | Computed | Deviation |
|---|---|---|---|
| G: sum of the base reactions, Fz [kN] | 970.15 | 970.15 | < 0.001% |
| G: girder A, y = 3 m (end span middle), M3 [kNm] | 4.08953 | 4.08953 | < 0.001% |
| G: bracket A, y = 24 m, V2 [kN] | -9.68625 | -9.68625 | < 0.001% |
| G: column A base, y = 24 m, My [kNm] | 60.3465 | 60.3465 | < 0.001% |
| F1: girder A, y = 24 m (support), M3 [kNm] | -80.2071 | -80.2071 | 0% |
| F1: girder A, y = 24 m (support), V2 [kN] | 69.3798 | 69.3798 | 0% |
| F1: bracket A, y = 24 m, M3 [kNm] | -69.2976 | -69.2976 | 0% |
| F1: bracket A, y = 24 m, V2 [kN] | -138.752 | -138.752 | 0% |
| F1: bracket A, y = 24 m, axial force [kN] | 5.39213 | 5.39213 | 0% |
| F1: tip of bracket A, y = 24 m, deflection uz [mm] | -0.882817 | -0.882817 | 0% |
| F1: column A base, y = 24 m, Fz [kN] | 137.703 | 137.703 | 0% |
| F1: column A base, y = 24 m, My [kNm] | -16.6446 | -16.6446 | 0% |
| F1: column B base, y = 24 m, My [kNm] | -41.0227 | -41.0227 | 0% |
| F1: lower wall brace A (y = 0-6), axial force [kN] | 6.63876 | 6.63876 | 0% |
| F1: girder A, y = 21 m, axial force [kN] | 9.24565 | 9.24565 | 0% |
| F1: girder A, y = 24 m, uy [mm] | 0.274292 | 0.274292 | 0% |
| F1: column A base, y = 0, Fy [kN] | -4.24106 | -4.24106 | 0% |
| F1: sum of the base reactions, Fy [kN] | -24.5 | -24.5 | 0% |
| F2: girder A, y = 24 m (support), M3 [kNm] | -81.1282 | -81.1282 | 0% |
| F2: bracket A, y = 24 m, V2 [kN] | -208.979 | -208.979 | 0% |
| F2: bracket A, y = 24 m, axial force [kN] | 8.8907 | 8.8907 | 0% |
| F2: column A base, y = 24 m, My [kNm] | -30.0562 | -30.0562 | 0% |
| F2: column B base, y = 24 m, My [kNm] | -66.9741 | -66.9741 | 0% |
| F2: lower wall brace A (y = 0-6), axial force [kN] | 13.4035 | 13.4035 | 0% |
| F2: girder A, y = 21 m, axial force [kN] | 9.45148 | 9.45148 | 0% |
| F2: girder A, y = 24 m, uy [mm] | 0.545425 | 0.545425 | 0% |
| F2: column A base, y = 0, Fy [kN] | -8.55981 | -8.55981 | 0% |
| F2: sum of the base reactions, Fy [kN] | -49 | -49 | 0% |
| K1: girder A, y = 3 m (end span middle), M3, largest [kNm] | 97.025 | 96.996 | 0.0299% |
| K1: girder A, y = 21 m (inner span middle), M3, largest [kNm] | 83.4435 | 83.3809 | 0.0751% |
| K1: girder A, y = 6 m (support), M3, smallest [kNm] | -86.9057 | -86.9057 | < 0.001% |
| K1: girder A, y = 24 m (support), M3, smallest [kNm] | -80.5194 | -80.5194 | < 0.001% |
| K1: girder A, y = 24 m (support), V2, largest [kN] | 116.553 | 115.286 | 1.09% |
| K1: bracket A, y = 24 m, M3, smallest [kNm] | -69.3629 | -69.3683 | 0.0077% |
| K1: bracket A, y = 24 m, V2, smallest [kN] | -138.872 | -138.883 | 0.0077% |
| K1: tip of bracket A, y = 24 m, deflection uz, smallest [mm] | -0.833515 | -0.833515 | < 0.001% |
| K1: column A base, y = 24 m, Fz, largest [kN] | 137.918 | 137.929 | 0.0077% |
| K1: column A base, y = 24 m, My, smallest [kNm] | -4.82027 | -4.82048 | 0.0043% |
| K1: column B base, y = 24 m, My, smallest [kNm] | -22.5884 | -22.5908 | 0.0105% |
| K1 light: girder A, y = 3 m (end span middle), M3, largest [kNm] | 35.1634 | 35.1529 | 0.0299% |
| K1 light: girder A, y = 24 m (support), M3, smallest [kNm] | -29.1815 | -29.1815 | < 0.001% |
| K1 light: bracket A, y = 24 m, V2, smallest [kN] | -50.3294 | -50.3333 | 0.0077% |
| K1 light: column A base, y = 24 m, Fz, largest [kN] | 49.9838 | 49.9876 | 0.0077% |
| K2: girder A, y = 3 m (end span middle), M3, largest [kNm] | 100.892 | 100.853 | 0.0389% |
| K2: girder A, y = 21 m (inner span middle), M3, largest [kNm] | 104.192 | 104.145 | 0.0450% |
| K2: girder A, y = 6 m (support), M3, smallest [kNm] | -120.003 | -120.004 | < 0.001% |
| K2: girder A, y = 24 m (support), M3, smallest [kNm] | -113.546 | -113.546 | < 0.001% |
| K2: girder A, y = 24 m (support), V2, largest [kN] | 170.661 | 169.003 | 0.971% |
| K2: bracket A, y = 24 m, M3, smallest [kNm] | -104.479 | -104.472 | 0.0062% |
| K2: bracket A, y = 24 m, V2, smallest [kN] | -209.126 | -209.113 | 0.0062% |
| K2: tip of bracket A, y = 24 m, deflection uz, smallest [mm] | -1.27635 | -1.27631 | 0.0028% |
| K2: column A base, y = 24 m, Fz, largest [kN] | 207.614 | 207.601 | 0.0063% |
| K2: column A base, y = 24 m, My, smallest [kNm] | -9.64052 | -9.64092 | 0.0042% |
| K2: column B base, y = 24 m, My, smallest [kNm] | -37.7186 | -37.7163 | 0.0059% |
| K1 dropped: girder A, y = 3 m (end span middle), M3, largest [kNm] | 110.019 | 109.995 | 0.0214% |
| K1 dropped: girder A, y = 21 m (inner span middle), M3, largest [kNm] | 94.598 | 94.5531 | 0.0475% |
| K1 dropped: bracket A, y = 24 m, V2, smallest [kN] | -138.872 | -138.883 | 0.0077% |
| K1 dropped: column A base, y = 24 m, Fz, largest [kN] | 137.918 | 137.929 | 0.0077% |
The plan of the hangar shows the crane girders on both sides (A and B, at 7.5 m), the columns, the sections read and, dashed, the braced end bays. The horizontal axis is the length of the hangar (y), the vertical one its span (x), and dimensions are in metres.
Note. The crane values are an example. A crane has two wheels on each rail, 4 m apart, and with the trolley next to rail A a wheel on rail A carries 89.9 kN and a wheel on rail B 32.6 kN. The K rows are envelopes: as the crane travels along the rail, they give the largest or the smallest value each quantity takes. K1 is one crane, K1 light the crane with its trolley next to rail B, K2 two cranes at least 1.5 m apart, and in these rows only the wheels on rail A are loaded. In the viewer's Z1 and Z2 envelopes the crane stands on both rails, so their values differ from the K rows by a few per mille. The F rows give the moment the crane stands at one position. There the crane loads bracket A the most, and every wheel also carries a braking force of 10 per cent of its load along the rail and a lateral force of 5 per cent across it. Since SAP2000 applies only the vertical load in a moving load analysis, braking and the lateral force are compared in the F rows. Every wheel is counted; the K1 dropped rows show SAP2000's default setting, which leaves out a wheel that lowers the value. The 1 per cent difference in the support shear comes from the two programs placing a wheel at a different distance from the section.
Model files
The SAP2000 model that produced the results in the table can be downloaded. It opens in SAP2000 27
and later with File > Import > SAP2000 .s2k Text File.