高速铁路斜拉桥钢-混组合箱梁受力及变形性能试验研究

为研究设计速度350 km/h高速铁路斜拉桥钢-混组合箱梁的受力特性与桥面变形性能,采用Ansys软件建立赣江特大桥3个梁段的有限元模型,分析其应力分布特性;以应力等效的原则优化设计出相似比为1∶3的全截面静载试验模型并开展受力传力及桥面变形特性研究。结果表明:钢-混组合箱梁在轴力及弯矩最不利荷载组合工况下,混凝土桥面板、钢梁最大压应力分别为8.36、107.2 MPa;其中钢主梁顶板与底板应力值较高,为受力关键区域;实测应力值与原桥理论值相符良好;混凝土桥面板与钢主梁顶板之间无明显滑移发生。沿纵桥向轴力传力中,钢主梁传递轴力由35.35%增加到52.26%,混凝土桥面板传递轴力由64.65%降低至47.74%。竖向单线1.0倍ZK荷载加载及双线交替增加至1.6倍时,主梁两侧高差均小于0.5 mm,小于轨道2 mm/5 m(3 m)的高低(扭曲)精度要求;在双线ZK列车竖向荷载下,纵横向挠度均呈正弦波分布,节间挠跨比分别为1/2631、1/2123,小于规范规定的1/1600。高速铁路钢-混组合箱梁具有良好的受力与变形性能。

Experimental Study on Mechanical and Deformation Performance of Steel-concrete Composite Box Girder of High-speed Railway Cable-stayed Bridge

To study the mechanical behavior and deck deformation performance of the steel-concrete composite box girder of a cable-stayed bridge of high-speed railway with a design speed of 350 km/h,a finite element model with 3 girder segments was established to analyze the stress distribution of the Ganjiang Bridge using Ansys software.A 1∶3 scaled test specimen with full cross-section was optimized according to the principle of stress equivalence and the static tests under the most unfavorable load cases were carried out to study the mechanical behavior as well as the deformation performance of the deck.The results show that the maximum compressive stresses of the concrete bridge deck and steel girder are 8.36 MPa and 107.2 MPa respectively under the cases of the most unfavorable load combination of axial force and bending moment.The top and bottom plates of the major steel girder show higher stress values,indicating they are the key areas of stress.The measured stresses are in good agreement with the calculated stresses of the original bridge.No obvious slip occurs between the concrete deck slab and the top plate of the steel girder.The axial force transferred by the steel girder increases from 35.35%to 52.26%while that of the concrete deck decreases from 64.65%to 47.74%.Under the one-line ZK Load and alternately increasing to 1.6 times of double line ZK Load,the measured height difference between the two sides of the main girder is less than 0.5 mm,which is lower than the height difference(torsional)limit values of 2 mm/5 m(3 m)of the track.Under the two-line ZK train load,the longitudinal and transverse deflections show smooth sine waves,and the longitudinal and lateral ratio of deck deflection to span is 1/2631 and 1/2123,less than the limit(1/1600)specified by the high-speed railway bridge design code.The steel-concrete composite box girder for high-speed railway has good mechanical and deformation performance.