高强轻骨料混凝土梁的长期性能试验研究

进行了28d强度为60.8MPa和64.4MPa的3根高强轻骨料混凝土梁近1年的长期荷载试验。试验结果表明,在持续荷载作用下,轻骨料混凝土梁的长期变形在初期发展较快,后期发展较慢;受压区配筋能够约束梁的长期变形发展,配筋率越高,长期变形越小。结合编制的混凝土结构长期性能分析程序,基于材料收缩和徐变试验数据,对试验梁进行了计算分析,计算值与试验结果吻合较好。还分别采用几个规范方法对长期挠度增大系数进行了分析,结果表明,ACI318和ACI435方法与试验结果比较吻合,而《混凝土结构设计规范》(GB 50010-2002)与《轻骨料混凝土桥梁技术规程》(报批稿)的计算结果对试验偏于不安全。

LONG-TERM DEFLECTION OF HIGH-STRENGTH LIGHTWEIGHT AGGREGATE CONCRETE BEAMS

Three high-strength lightweight aggregate concrete(LWAC) beams were experimented for long-term deflections,which lasted for nearly 1 year,with the average 28-day compressive strength 60.8MPa and 64.4MPa.From the test results it is observed that long-term deflections developed quickly at early ages and reinforcement ratio for compression steel had a significant effect on time-dependent deflections.Finite element methods had been developed to account for time-dependent deflections of reinforced concrete members and a good agreement was achieved.It is found that ACI318 and ACI435 methods had resulted in good estimates for the time-dependent deformation and the design methods of current Chinese codes may be unsafe.