斜拉桥单向预应力体系索塔锚固区足尺模型试验研究

为研究布置单向预应力的混凝土索塔锚固区的传力机理,明确该类新型索塔锚固区的实际受力状况,以广中江高速公路西江水道桥为工程背景,进行了索塔节段足尺模型试验和有限元数值分析,试验中特制了与实桥一致的平行钢丝索短索,并设计了斜向加载反力梁,以模拟斜拉索的大吨位斜向荷载;试验过程中观测结构的应力、变形以及裂缝发展.研究结果表明:理论分析与试验结果吻合较好,结构在1.2倍设计荷载下仍处在弹性受力状态,主要受力部位未发现裂缝;推算抗裂安全系数为2.04,布置在顺桥向塔壁的单向预应力能够提供足够的压应力储备.

Full-scale Model Test of Pylon Anchorage Zone with One-way Prestressing Tendons in Cable-stayed Bridge

In order to study the mechanism of new one-way pre-stressed tendons applied to cable-pylon anchorage zone, as well as to clarify the actual stress distribution of the tendons, a full-scale model test and finite element analysis were conducted. As the construction background, Xijiang River Bridge of Guangzhou - Zhongshan - Jiangmen highway was considered. To simulate the large-tonnage inclined load of the cable, four short parallel wire cables and a reaction beam were designed and manufactured. Strains, displacements, and cracks of the structure were measured. The predictions by the finite element analysis agreed well with the test results. The linear strain distributions of the structure were measured even at 1.2 times of designed load, and cracks did not occur in the main load-resisting members. In addition, the safety coefficient 2.04 was estimated to prevent cracks, and enough prestress reserve was provided by the one-way pre-stressed tendons placed in the longitudinal direction wall.