摘要:
物流业的兴起催生了物流建筑的概念,物流建筑具有荷载大、跨度大、层高高等特点。对于这种建筑,现有的钢-混凝土组合梁和型钢混凝土梁不仅价格昂贵,而且资源消耗大,这与国家倡导的新型绿色施工模式背道而驰。在实际工程应用中,业主迫切需要降低工程成本,因此为此类建筑开发新的水平构件尤为重要。为了解决上述问题,将部分包覆混凝土梁(PECB)与无支撑施工方法相结合,提出了一种预制装配部分包覆混凝土梁(PPECB)。为了研究预制装配部分包覆混凝土梁的剪切性能,设计了8根部分预制梁和1根PEC梁(整体浇筑对比试件)来研究剪切性能。主要目的是观察和记录整个试验过程,获得预制装配部分包覆混凝土梁试件在竖向荷载作用下的剪切破坏特征、裂缝发展、应变发展规律、荷载-跨中挠度曲线;阐明预制装配部分包覆混凝土梁的剪切破坏机理;探讨了浇筑方式、钢腹板厚度、混凝土强度、箍筋直径、箍筋间距和剪跨比对预制装配部分包覆混凝土梁抗剪性能的影响;建立了预制装配部分包覆混凝土梁斜截面的抗剪承载力模型,推导了预制装配部分包覆混凝土梁斜截面抗剪承载能力的计算方法。试验结果表明:预制装配部分包覆混凝土梁能够基本保持整体工作性能,这与现浇部分外包混凝土组合梁(PECB)的抗剪性能更加一致,其抗剪承载力略低于现浇部分外包混凝土组合梁。总体上,认为浇筑和预制的不同浇筑方法对构件的承载力影响较小;预制装配部分包覆混凝土梁的剪切破坏模式为剪切破坏。最大裂纹在屈服前发展缓慢,屈服后发展迅速;混凝土强度、箍筋间距和直径对裂缝发展速率影响较大;随着混凝土强度等级的提高,预制装配部分包覆混凝土梁的抗剪承载力增加;预制装配部分包覆混凝土梁的抗剪承载力随着钢腹板厚度的增加而增加;增大箍筋直径和减小箍筋间距都可以提高预制装配部分包覆混凝土梁的抗剪承载力;当剪跨比在1.5~2.5之间时,预制装配部分包覆混凝土梁的抗剪承载力随着剪跨比的增大而减小;参考现有规范,初步给出了预制装配部分包覆混凝土梁的抗剪承载力计算公式。基于此理论,计算结果与试验值吻合较好,可为实际工程应用提供参考。
关键词:
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预制 /
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部分包覆混凝土 /
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梁 /
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受剪
Abstract:
The rise of logistics industry has given birth to the concept of logistics architecture, which is characterized by large load, large span and high floor height. For such buildings, the existing steel-concrete composite beams and steel reinforced concrete beams are not only expensive, but also resource consuming, which runs counter to the new green construction mode advocated in our country. In practical engineering applications, the owner urgently needs to reduce the project cost. Therefore it is particularly important to develop new horizontal components for such buildings. In order to solve the above problems, a prefabricated partially encased concrete beam(PPECB) by combining partially encased concrete beam(PECB) with unsupported construction method is proposed in this paper. In order to study the shear behavior of prefabricated partially encased concrete beams, eight partially prefabricated beams and one PEC beam(monolithic casting comparison specimen) were designed to study the shear behavior. The main purpose is to observe and record the whole test process, and obtain the shear failure characteristics, crack development, strain development law, and mid-span deflection curve of prefabricated partially encased concrete beams under vertical load. The shear failure mechanism of precast partially encased concrete beams is clarified. The influence of pouring method, steel web thickness, concrete strength, stirrup diameter, stirrup spacing and shear span ratio on the shear performance of precast partially encased concrete beams is discussed. The shear bearing capacity model of precast partially encased concrete beams is established, and the calculation method of shear bearing capacity of precast partially encased concrete beams is deduced. The test results show that the prefabricated partially encased concrete beam can basically maintain the overall working performance, which is more consistent with the shear performance of the cast-in-place partially encased concrete composite beam(PECB), and its shear bearing capacity is slightly lower than the cast-in-place partially encased concrete composite beam. In general, it is considered that the different pouring methods of pouring and prefabrication have little influence on the bearing capacity of specimens. The shear failure mode of prefabricated partially encased concrete beams is shear failure. The largest crack develops slowly before yielding and rapidly after yielding. The concrete strength, stirrup spacing and diameter have great influence on the crack development rate. With the increase of concrete strength grade, the shear capacity of prefabricated partially encased concrete beams increases. The shear capacity of prefabricated partially encased concrete beams increases with the increase of steel web thickness. Increasing the diameter of stirrups and decreasing the spacing of stirrups can improve the shear capacity of prefabricated partially encased concrete beams. When the shear span ratio is between 1.5 and 2.5, the shear capacity of prefabricated partially encased concrete beams decreases with the increase of shear span ratio. With reference to the existing specifications, the formula for calculating the shear capacity of prefabricated partially encased concrete beams is preliminarily given. Based on this theory, the calculated results are in good agreement with the test values, which can provide reference for practical engineering applications.