混凝土连续箱梁长期受力性能试验研究

目前混凝土连续箱梁普遍存在开裂等病害现象,研究表明混凝土连续箱梁设计理论的不完善是引起结构开裂的重要原因之一.对钢筋混凝土连续箱梁模型均布荷载作用下的长期受力性能进行1006 d的试验观测表明:受拉钢筋的应变增长相对较小,受压钢筋和受压混凝土的应变增长相对较大,且跨中截面的压应变增长较中间支座截面显著,中间支座截面受压翼缘有效分布宽度系数较跨中截面增加更显著.对试验模型持荷1006 d的内力重分布规律进行试验观测,与理论预测结果吻合较好.对现行设计规范进行参数修正后能较好地预测连续箱梁各控制截面的裂缝宽度,跨中长期挠曲变形实测值较理论计算值偏大约11.4%.

Experimental study on the long-term behavior of concrete continuous box girders

At present concrete continuous box girders generally have cracking and other deteriorations, research indicates that imperfection in the design theory of concrete continuous box girders is one of the important reasons causing structure cracking. Long-term behaviors were tested for 1006 days on a reinforced concrete continuous box girder model under uniform loading. The strain of tensile steel bars would change little, the compressive strain of steel bars and concrete would change rather significantly under sustained load, and the strain increase at the mid-span section would be larger than that at the mid-supported section. The increase in the effective distribution width coefficient of compressive flange at the mid-supported section would be larger than that at the mid-span section. The internal force redistributions of the experimental model were tested for 1006 days, and the test data agree well with the theoretical values. By modifying the relative parameters of the updated design code, the theoretical crack width at dominant sections would agree well with the actual values. The actual long-term deflection at the mid-span would be larger than the theoretical values in the updated design code by 11.4%.