再生大骨料自密实混凝土梁正截面受力特性研究

Study on the Normal Section Mechanical Characteristics of Self-compacted Concrete Beam with Recycled large Aggregate

梁的正截面受力特性是梁构件内力分析的前提条件。为了研究再生大骨料自密实混凝土梁的正截面受力特性,本研究以再生大骨料配比为变量,设计了三根再生大骨料自密实混凝土梁(PH1、PH2、PH3),进行了四点弯梁试验,获取了梁破坏的相关参数指标,分析了梁跨中截面混凝土应变沿截面高度的变化规律,以及天然毛石含量对裂缝开展和梁承载能力的影响。研究结果表明:1)再生大骨料自密实混凝土梁满足平截面假定;2)与普通混凝土梁相同,再生大骨料自密实混凝土梁也具有明显的弹性、开裂、屈服和极限四个受力特点;3)随着天然毛石含量的增加,再生大骨料自密实混凝土梁的开裂荷载逐渐降低,而极限承载力逐渐增大;4)天然毛石的加入影响再生大骨料自密实混凝土梁裂缝产生的位置和开展轨迹。部分裂缝的产生位置不再是梁底部,裂缝开展轨迹也沿非平截面方向发展。

The normal section mechanical characteristics of beam are the precondition of the internal force analysis of beam component.In order to study the normal section mechanical characteristics of recycled large aggregate self-compacted concrete beam,taking the aggregate proportion as variable,three recycled large aggregate reinforced self-compacted concrete beams（PH1,PH2,PH3）were designed for three-point loading experiment.The relevant parameters of beam failure were obtained.The variation pattern of mid span section strain along section height and the effect of natural rubble content on the crack development and bearing capacity were analyzed.Results show that 1）recycled large aggregate self-compacted concrete beam satisfies plane section assumption.2）As same as ordinary concrete beam,recycled large aggregate self-compacted concrete beam has four obvious mechanical characteristics,including elastic,cracking,yielding and ultimate stress.3）With the increase of natural rubble content,the cracking load of recycled large aggregate self-compacted concrete beam decreases gradually,but the ultimate bearing capacity gradually increases.4）The effect of adding natural rubble on recycled large aggregate self-compacted concrete beam is exhibited by the location of crack initiation and crack development trajectory.The initiation location of partial crack is no longer the beam bottom,and partial crack development trajectories are along non-plane cross section direction.