缓粘结部分预应力混凝土梁等幅疲劳性能试验研究

自行研制配制出满足后张法有粘结预应力混凝土的缓凝砂浆.根据12根缓粘结部分预应力混凝土梁静载以及等幅疲劳荷载作用下的试验结果,得到了钢筋和混凝土的应变增量、梁的裂缝宽度和挠度随重复荷载循环次数的增加而增长的规律,及部分预应力混凝土梁的疲劳破坏始于非预应力钢筋的疲劳断裂的结论.缓粘结部分预应力混凝土梁与同条件下通过灌浆浇筑的部分预应力混凝土梁相比,疲劳寿命较高.建议了预应力损失的计算公式和部分预应力混凝土梁疲劳验算的计算公式,对试验梁进行了结构静力计算和疲劳验算,计算结果与试验结果吻合较好.

Experimental research on constant-amplitude fatigue behavior of retard-bonded partially prestressed concrete beams

Retarding mortar which meets the requirements of the bonded post-tensioned prestressed concrete is developed. 12 retard-bonded partially prestressed concrete (P.P.C) T-beams are tested. There are two kinds of loadings, one is static loading, and the other is constant-amplitude fatigue loading. The strain increment of reinforcement and concrete, crack width and deflection versus number of cycles under constant-amplitude fatigue loading are obtained from the test results. In addition, the conclusion is drawn that the damage of P.P.C beams is due to the fracture of non-prestressed reinforcement. Compared with the T-beams in the same conditions except job practice, fatigue life of retard-bonded P.P.C T-beams is much longer. Based on the test results, the formulas for prestress loss and fatigue calculation of P.P.C T-beams are recommended, and the calculating results match with the test results well.