Software Verification SAP2000 6
PROGRAM NAME: REVISION NO.:
EXAMPLE 7-002 CABLE – UNIFORM AND CONCENTRATED LOADING PROBLEM DESCRIPTION In this example a suspended cable is subjected to uniform self-weight and concentrated loads. The geometry, properties and loading are as described in Section 4.6.2, Comparison Example 2, Figure 4.16 and Table 4.1 of Tibert, 1999 and are reproduced in the following figure. Two cable elements are used in the SAP2000 model, one for the cable segment between joints 1 and 2 and the other for the segment between joints 2 and 3. The displacement at point 2 is compared with results presented in Tibert, 1999. In the Sap2000 model point 2 is set at an arbitrary Z coordinate. The self-weight load is applied first and the cable automatically assumes the correct shape as a result of this analysis. Next the 8 kip load is applied continuing from the state at the end of the self-weight analysis (and including the loads from the self-weight case). To obtain the desired displacement, a response combination that combines the results of the self-weight load case with the point load case using a -1 multiplier on the self-weight case. GEOMETRY, PROPERTIES AND LOADING
Z 1
8 kips
X
3 100 ft
400 ft
2
500 ft 1000 ft Cable Properties Cable cross-sectional area = 0.85 in2 Equivalent modulus of elasticity = 19000 kips/in2 Cable self weight = 3.16 lb/ft Undeformed length of cable segment 1-2 = 412.8837 ft Undeformed length of cable segment 2-3 = 613.0422 ft
EXAMPLE 7-002 - 1
Software Verification PROGRAM NAME: REVISION NO.:
SAP2000 6
TECHNICAL FEATURES OF SAP2000 TESTED Uniform load applied to cable elements Concentrated load applied to cable elements Response combination results Nonlinear static analysis RESULTS COMPARISON The independent results are those for the elastic catenary shown in Table 4.2 of Tibert, 1999.
Output Parameter
SAP2000
Independent
Percent Difference
Point 2 X-dir Displacement, ft
-2.819
-2.819
0%
Point 2 Z-dir Displacement, ft
-18.457
-18.457
0%
COMPUTER FILES: Example 7-002 CONCLUSION The SAP2000 results show an exact comparison with the independent results.
EXAMPLE 7-002 - 2