To investigate the structural behavior of segmental precast prestressed concrete box girder un-der the regular service stage and the construction state,a span of 48 m full scale box girder model of this type was tested for the Fourth Nanjing Yangtze River Bridge approach. The assembling and loading plans were de-termined according to the geometric parameters as well as the actual constraints of the girder. This paper focuses on the static performance,such as stress and displacement changes of the girder during segment loading and transporting. Comparative finite element method analysis was also performed for checking. The model test results show that at the regular service stage,the residual deformation of the girder after unloading is small,which demonstrates that the girder keeps in elastic during loading. The tooth joints of segments work well with each other and have no relative slip;the global performance of the girder is good as monotonous. The vertical distribution of longitudinal strain at joint and between joints basically accords with hypothesis of plane section. Also,the stress increment of prestress tendons is linear to the mid-span moment change. Finally,during the segment trans-port stage,it shows that there is sufficient compressive stress of the lower flange of the girder to meet the security requirements of transporting girder.% 以南京长江第四大桥引桥为背景，开展了一孔48 m跨径体内-体外混合配束节段预制拼装箱梁的足尺模型试验，以研究该类箱梁在正常使用阶段和施工状态下的结构行为。根据试验箱梁的尺寸参数以及实际约束条件确定了拼装与加载方案。本文重点研究正常使用荷载和梁上运梁两种工况下梁体应力状况与位移变化等结构静力性能，并与试验梁实体有限元模型进行对比分析。研究结果表明：在正常使用阶段，加、卸载后拼装梁体残余变形较小，基本处于弹性工作状态，整体性较好；键齿接缝两侧基本无相对滑移，接缝截面纵向应变沿梁高大致呈线性变化，力学行为基本符合平截面假定；体外预应力束在转向处基本无滑移，体内外预应力增量随跨中弯矩基本呈线性变化；在梁上运梁工况下，实测梁体下缘压应力储备充足，满足运梁安全性要求。
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