重复荷载作用下无粘结部分预应力高强混凝土梁正常使用阶段性能研究

通过26根无粘结部分预应力高强混凝土梁,研究了影响裂缝宽度及裂缝闭合和变形的主要因素,将无粘结部分预应力高强混凝土梁在使用荷载作用下的受力状态转化为偏心受压构件的受力状态,求解非预应力筋的应力,然后采用现有规范裂缝宽度计算公式来求无粘结部分预应力高强混凝土梁的裂缝宽度,并建立了重复荷载作用下的无粘结部分预应力高强混凝土梁裂缝宽度计算公式;应用名义拉应力建立了闭合弯矩计算公式.将预应力筋和非预应力筋对无粘结梁跨中最大挠度的影响,用无粘结配筋指标和综合配筋指标之比η和换算配筋率αpρ这两个参数来反映,并且采用与国内有关规范相一致的直接双直线法,建立了任意荷载作用下的无粘结部分预应力高强混凝土梁变形计算公式.计算结果与试验结果吻合较好.

RESEARCH ON THE BEHAVIOR OF UNBONDED PARTIALLY PRESTRESSED HIGHSTRENGTH CONCRETEBEAMS UNDER A REPEATED LOADING

An experimental result of 26 pieces of unbonded partially prestressed high -- strength concrete beams is performed in the paper. An attempt is made to study some major factors that affect crack width, crack closure, and deformation of a unbonded partially prestressed concrete (PPC) beam. The state under service load of unbonded partially prestressed high-strength concrete beams can be considered as an eccentric compression for a member. The formula for crack width in the present cods is adopted to calculate the crack width of unbonded prestressed high-strength concrete beams. Then a crack width formula for unhanded prestressed high-strength concrete beams under repeat load is established. The formula for closed bending moments is obtained based on the normal tensile stress. The calculating results are matched with the test results well.