Post-tensioning Effects

The post-tensioning tendons were modeled using equivalent load effects. The effective anchorage force of each tendon after losses was determined to be 352 kips for the strong axis tendons and 224 kips for the minor axis tendons. The equivalent uniform uplift of the tendons was determined to be 68 psf by using the simplified load balancing model. This assumes that the effective stress, f se, in the

tendons considering time-dependent losses was equal to 0.6 fpu , which is 144 ksi. Figure 5 shows a

simplified load-balancing model with two “super tendons” along the major and minor axes to represent all post-tensioning tendons in the structural roof.

Figure 5. Equivalent force system of PT tendons.

The roof system was modeled with equivalent post-tensioned beams forming a 10 ft. waffle grid. The equivalent section that includes the precast panels is shown in Figure 6.

120

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PT Tendon

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Figure 6. Equivalent roof post-tension beam cross section detail.