The main bridge of the Changmen Bridge is a hybrid girder cable-stayed bridge with double pylons,double cable planes and with the main span of 550 m.The structural system of the bridge is the rigid fixity system of the pylons,main girder and piers.To analyze the mechanical be-havior of a rigid fixity area of the pylon,main girder and pier of the bridge,the scale-down model of 1:5 for the rigid fixity area was designed and fabricated,the model tests for the area were car-ried out and the stresses,displacement and cracking safety of the area at the service stage were studied.The results of the study reveal that under the design loads,the stresses of the critical sec-tions of the rigid fixity area can satisfy the relevant requirements in the codes,the vertical displace-ment of the concrete main girder and the lower cross beam of the pylon is little,the structure is safe and has sufficient bending and shear rigidity.The cracking moment of the concrete main girder in the area measured in the tests is far greater than the maximum cracking moment under the de-signed loads and the cracking safety and safety margin of the main girder is quite great.%长门特大桥主桥为主跨550 m的双塔双索面混合梁斜拉桥,采用塔梁墩固结体系.为分析该桥塔梁墩固结区的受力特性,设计制作缩尺比1:5的塔梁墩固结区模型进行试验,研究塔梁墩固结区在使用阶段的应力、位移和抗裂安全性.结果表明:在设计荷载作用下,塔梁墩固结区各关键截面应力均满足规范要求,混凝土主梁和下横梁的竖向位移较小,结构安全且具有足够的抗弯和抗剪刚度;试验测得的固结区主梁混凝土开裂弯矩远大于设计荷载作用下最大弯矩,混凝土主梁具有较大的抗裂安全性和安全储备.
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