无黏结预应力混凝土梁短期裂缝试验

Experimental research on short-term crack of unbonded prestressed concrete beams

通过八根无黏结预应力混凝土梁和两根普通混凝土梁的短期裂缝试验,研究了配置HRBF500钢筋的无黏结预应力混凝土梁的裂缝间距和宽度,并对'混凝土结构设计规范GB50010—2010';裂缝计算公式的适用性进行了评析.研究表明:规范GB50010的裂缝计算模式对配HRBF500钢筋的无黏结预应力混凝土梁仍适用,但按规范GB50010计算的平均裂缝宽度和最大裂缝宽度总体上比试验值偏大,计算值与试验值之比平均分别为1.333和1.403.根据试验结果,建议将裂缝间混凝土伸长对裂缝宽度的影响系数αc和短期裂缝宽度扩大系数τs调整为0.58和1.54,调整后的计算值与试验值符合较好.

The crack spacing and crack width of the unbonded prestressed concrete beams with HRBF500 steel bars were researched by short-term tests of 8unbonded prestressed concrete beams and 2reinforced concrete beams,while the formulae for crack spacing and crack width in code for design of concrete structures GB50010—2010 were evaluated.The research shows that the original method in code GB 50010—2010is applicable to unbonded prestressed concrete beams with HRBF500 steel bars,but the calculated values of average crack width and maximum crack width are generally larger than those test values with the average ratios of 1.333 and 1.403.Based on the test results,the influence coefficient of elongation of concrete to crack widths between cracksαcand the expansion coefficient of short-term crackτsare suggested to modify to 0.58 and 1.54.The average ratios of the modified values of average crack width and maximum crack width agree well with the experimented ones.