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本文报告了33根矩形截面直线配筋和2根T形截面配置曲线预应力筋的无粘结部分预应力砼梁的裂缝宽度的试验研究成果。试验表明,在无粘结预应力砼梁中配置普通有粘结筋对梁在开裂后的裂缝分布有重要影响。本文分析了影响裂缝宽度的主要因素,根据预应力筋与周围砼无粘结而可互相滑动的特点,提出了将预应力筋对砼的预压力作为截面上的纵向压力,求解与弯矩共同作用下普通有粘结筋的应力(?),而后引用普通钢筋砼构件裂缝宽度的公式计算普通钢筋(?)水平处的裂缝宽度和近似计算预应力筋(?)。水平处的裂缝宽度。用本文33根矩形截面梁的裂缝宽度试验数据及文献[2]的数据对所建议的计算方法进行了校核,符合程度较好。此外用本文报告的2根6m跨长配置曲线预应力筋的无粘结部分预应力砼T形梁进行了补充验证,得出最大裂缝宽度的计算值略大于试验值而偏于保守。最后对最大裂缝宽度允许作了讨论。
This paper reports the experimental research results of the crack widths of unbonded partially prestressed trussed girders with 33 prefabricated steel bars with rectangular sections and two T-section profiles. Tests have shown that the configuration of ordinary bonded ribs in unbonded prestressed truss beams has an important effect on the distribution of cracks in the cracked beam. In this paper, the main factors affecting the crack width are analyzed. According to the characteristics that the prestressed tendons do not stick to each other and can slide with each other, the pre-stress of the prestressed tendons to the concrete is proposed as the longitudinal pressure on the cross section. Solving and bending moments are common. Under normal circumstances, the stress (?) of the bonded tendons is used, and then the crack width at the level of ordinary steel (?) is calculated by using the formula for the crack width of ordinary reinforced concrete components and approximate calculation of the prestressed tendons (?). Crack width at the level. Using the test data of the crack widths of 33 rectangular cross-section beams in this paper and the data in [2], the proposed calculation method was checked and the degree of coincidence was good. In addition, the unbonded part of the prestressed concrete T-shaped beams with two 6-meter-long configuration curves reported in this paper were supplemented and verified, and the calculated maximum crack width was slightly larger than the experimental value and was conservative. Finally, the maximum crack width is allowed to be discussed.