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某单跨厂房,跨度为15m,柱距6m,无天窗,有悬挂电动单梁吊车一台(起重量1t,L_k=9m,动力系数1.1)。选用国标G353(六)SL15-3Ca双坡薄腹屋面梁,混凝土设计等级为C30。屋面梁吊装前发现混凝土强度远达不到设计要求,须对薄腹梁补强加固。本文通过补强设计计算,说明补强加固原理、构造措施以及施工过程。 一、混凝土强度偏低原因分析 经分析,由于水泥标号发生问题,加之混凝土套用经验配合比,未采用实验室配合比,造成混凝土强度偏低。经试块抗压试验和现场“回弹法”,测定混凝土实际强度等级在C15～C30之间,7根薄腹梁强度评定结果分别为28.7,25.6,23.8,24.7,
A single-span factory building with a span of 15m, a column spacing of 6m, no skylights, and an electric single-girder hoist (upload 1t, L_k=9m, power coefficient 1.1). The national standard G353 (Six) SL15-3Ca double-slope thin-walled roof beams was selected and the concrete design grade was C30. Before the roof beam is lifted, it is found that the concrete strength is far from the design requirements and it is necessary to reinforce and reinforce the thin-web beam. In this paper, reinforcement design calculations are used to illustrate the reinforcement and reinforcement principles, construction measures and construction process. First, the analysis of the causes of low concrete strength Through analysis, due to the problem of cement marking, combined with the experience of the concrete mix ratio, did not use the laboratory mix, resulting in low concrete strength. After the compressive test of the test block and the site “rebound method”, the actual strength grade of the concrete was measured between C15 and C30, and the evaluation results of the strength of 7 thin-web beams were 28.7, 25.6, 23.8, and 24.7, respectively.