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对5片配置不同强度等级非预应力筋的无粘结部分预应力混凝土试验梁进行了加载试验,研究了该结构正常使用阶段和承载能力极限状态下,非预应力筋的强度等级以及高强非预应力筋配筋率对预应力筋应力增量的影响,并根据各国规范对试验梁极限应力增量的计算值与实测值进行了对比分析。研究结果表明:非预应力筋的强度等级差别及配筋率在弹性工作阶段对预应力筋的应力增量影响很小,但在混凝土开裂后至破坏阶段影响显著。各国规范极限应力增量计算值和实测值相比,我国现行规范计算结果更为安全合理。
Five unbonded partially prestressed concrete test beams with different prestressing tendons with different strength grades were tested with load test. The strength of non-prestressed tendons and the strength of non-prestressed tendons under normal load and ultimate load were studied. The influence of the prestressing tendon reinforcement ratio on the stress increment of the prestressing tendons was analyzed and compared with the calculated value and the measured value of the ultimate stress increment of the test beam according to the national norms. The results show that the difference of strength grade and reinforcement ratio of non-prestressed tendons have little effect on the stress increment of prestressing tendons in the elastic working stage, but have significant influence after the cracking of concrete to the damaged stage. Compared with the measured values of the normalized ultimate stress increment in various countries, the calculation results of the current norms in our country are more safe and reasonable.