【摘要】 为了研究荷载水平对长期加载作用下混凝土的剩余承载力的影响,对混凝土预制缺口梁首先施加60%和80%极限荷载并进行持续6个月和12个月加载。长期加载试验结束后,一部分混凝土梁从加载架取出并且在静载条件下加载到破坏。而另外一部分混凝土梁进行更高荷载水平的持载试验。在试验过程中得到混凝土梁加载点位移随时间的变化曲线以及静载条件下的荷载-位移曲线。根据试验结果可以得到长期加载作用后混凝土的起裂荷载、剩余承载力以及断裂能。结果表明,长期荷载作用后,混凝土的起裂荷载和剩余承载力有明显的提高。且荷载水平越高,徐变后混凝土剩余承载力越大。长期荷载作用对混凝土断裂能没有影响。此外,80%极限荷载持续加载12个月后的混凝土时间在伴随试件极限荷载的持续加载作用下仍然可以在一段时间内保持稳定不发生破坏。更多还原

【Abstract】 In order to investigate the effects of load levels on the residual capacity of concrete under long-term loading,pre-notched concrete beams were firstly subjected to sustained loads of 60% and 80% peak load( Pmax) with a duration of 6 months and 12 months. After the long term loading tests,the creep specimens were removed from loading frames and immediately loaded up to failure. The loading point displacement versus time and load-crack mouth opening displacement curves was obtained from the tests. According to the experimental results,the initial cracking load,residual capacity and fracture energy can be calculated as well. The results indicated that comparing with the concrete under static loading condition and residual capacity of creep concrete had increments. Meanwhile,the residual capacity of creep concrete will increase with the increase of load levels. The fracture energy almost had no effects on the long-term loading. In addition,the sustained loading tests under Pmax from static loading condition were carried out for the beams under 80% Pmaxafter 12 months sustained loading. The results indicated that the creep concrete could maintain stability for a period.更多还原