后张预应力预制混凝土框架梁柱节点抗震性能试验研究

Experimental study on seismic performance of Post-Tensioned Prestressed Precast Concrete beam-column assemblages

采用后张预应力筋将预制梁柱拼装在一起的连接方式属于延性连接,地震作用下塑性变形主要集中在连接部位,梁柱构件均保持弹性。采用这类连接的预制混凝土框架结构具有结构恢复性能好、耐久性好、有利于实现大跨度预应力混凝土框架结构的"梁铰耗能机制"等优点。为了研究其抗震性能,对4榀梁柱中节点进行低周反复加载试验。其中,2榀试件中预应力筋为有黏结,另外2榀预应力筋在梁端一定范围内设置为无黏结。试验结果表明,4榀试件的破坏主要集中在梁柱连接截面附近,梁柱构件本身及节点核心区破坏都比较轻微;与普通钢筋混凝土构件相比,试件滞回环面积较小,耗能能力较差,但残余变形较小,恢复性能较好;预应力筋在梁柱连接截面附近为无黏结的试件由于预应力筋没有达到屈服强度,耗能更小,恢复性能也更好;4榀试件最大楼层位移角介于0.359～0.439之间,大于我国抗震规范规定的框架结构最大弹塑性层间位移角限值,具有足够的变形能力。

The construction that connects the beams and columns by post-tensioning tendons provides ductile connections. When subjected to seismic loading, nonlinear behavior occurs in the connections, while the beams and columns remain elastic. The precast reinibrced concrete frame adopting this type of construction has the advantages of favorable self-centering capacity and high grades of durability, and furthermore, it makes the ＂beam-hinge＂ energy dissipation mechanism possible for large-span prestressed reinforced concrete frames. To study its seismic performance, four beam-to-column assemblages were tested under cyclic reversal loads. For two test specimens, the post-tensioned strands are bonded all through the beams, while for the others the strands are designed to be unbonded near the beam end. The test results indicate that inelastic deformation concentrates near the beam-column connections, while damage of the beam, column and joint is relative minor. Comparing with the common concrete structure, the test specimens show less loop area and poor energy dissipation capability, while the self-centering ability is preferable since the residual drift is quite small. For the specimens with partially unbounded strands, the energy dissipation capability is even smaller and the self-centering ability is more remarkable. The uhimate drifts of the four specimens are between 0. 359 - 0. 439, which are bigger than the required values of Chinese seismic design code, so the deformation ability of these beam- column assemblages is enough.