自密实混凝土梁长期变形性能研究

对13根自密实混凝土梁在长期荷载作用下的变形性能进行了试验研究,探讨了早龄期加载时混凝土的固化程度、预加应力以及结构超静定次数对梁的长期变形性能的影响。试验研究和理论分析表明:(1)同组梁实测结果的离散性很小,自密实混凝土品质优良。(2)早龄期加载时混凝土的固化程度、预加应力以及结构超静定次数对梁的长期变形性能有较大的影响。(3)自密实混凝土梁的挠度徐变系数在1.0～1.8之间,在工程中采用自密实混凝土时一般不需要对自密实混凝土的徐变加以特殊考虑。(4)采用修正的MC90徐变和收缩模型及龄期调整有效模量法结合截面分析能较准确地计算自密实混凝土梁的徐变挠度。同时为自密实混凝土工程设计和结构分析提供可靠的试验依据。

Experimental study on the long-term behavior of self-compacting concrete beams

This paper reports the test results of 13 self-compacting concrete(SCC) beams.The effects of the degree of solidification of concrete at early stage of loading,the prestress force and the degree of indeterminacy on the long-term behavior of self-compacting concrete beams are investigated.Experimental study and theoretical analysis indicate that:(1) the variability of test results for the same group of SCC beams is very small,attributing to the good quality of SCC,(2) the degree of solidification of concrete at early age of loading,the prestress force and the degree of indeterminacy have great impacts on the long-term behavior of self-compacting concrete beams,(3) the deflection creep coefficient of SCC beams is between 1.0 and 1.8,thus extra preventions considering shrinkage and creep behavior are probably not needed,and(4) the test beams are modeled by section analysis using a modified MC 90 creep and shrinkage model and a age-adjusted effective modulus method.The calculated results agree well with the tests.