基于旧规设计理念的在役空心板梁抗剪性能对比

卢悄悄¹，宋淑琴²，赵鹍鹏^1*，梁茂景³

1.山东交通学院交通土建工程学院，山东 济南  250357；2.济南金曰公路工程有限公司，山东 济南  250101；

3.菏泽交通投资发展集团有限公司，山东 菏泽  274000

摘要：为分析目前在役旧空心板梁支点剪力区的抗剪性能，保障桥梁的使用安全性及耐久性，考虑板梁截面形式、普通钢筋布置方式、预应力钢筋张拉布置方法、混凝土材料强度、荷载作用组合等影响因素，采用软件MIDAS CIVIL分别按公路钢筋混凝土及预应力混凝土桥涵设计规范（JTJ 023—1985）、公路钢筋混凝土及预应力混凝土桥涵设计规范（JTG D62—2004）设计空心板梁模型S1、S2，在静力荷载和移动荷载下进行剪力分析；按缩尺比例1︰4，根据JTJ 023—1985、JTJ 062—2004要求分别设计制作试验梁T1、T2，采用分级加载方式加载至JTJ 062—2004正常使用极限状态和承载力极限状态设计荷载，直至试验梁破坏，对根据JT J023—1985、JTJ 062—2004设计的空心板梁在公路钢筋混凝土及预应力混凝土桥涵设计规范(JTG 3362—2018)车道荷载作用下进行抗剪性能研究，将有限元模型分析结果与缩尺模型加载试验结果进行对比。结果表明：1）在恒载作用下，空心板梁S1所受剪力普遍略小于S2，空心板梁S1、S2的最大剪应力随JTG 3362—2018道荷载组合效应的增大而大幅增大，分别增大26.8%、16.8%。2）试验梁T1、T2的试验现象类似，随荷载增大，加载点底板、纯弯段底板、剪压区先后出现裂缝，剪压区斜裂缝延伸为主裂缝，主裂缝附近出现次生裂缝，加载点横向裂缝延伸至腹板。3）试验梁T1的挠度比试验梁T2大。4）二者在加载初期，主拉应变和荷载大致呈线性关系，随荷载增大，中部主拉应变增速最快，底部次之，梁体中部剪压区首先出现裂缝，延伸至底部，顶部主拉应变变化较小；后期曲线斜率较大，荷载小幅增大时，应变增速过快，裂缝变化较大。5）试验梁T1和T2在加载至JTG 3362—2018设计承载能力极限状态时，试验梁T2的抗剪承载力安全系数不足；试验梁T1基本满足JTG 3362—2018的抗剪要求，但结构安全系数较小。6)试验梁T1和T2的挠度和应变校验系数满足要求，但在剪力区过早出现裂缝将直接影响桥梁使用耐久性，降低桥梁整体刚度。

关键词：桥梁工程；抗剪性能；在役空心板梁；对比试验

Comparison of shear performance of in-service hollow slab beams based on abandoned standards

LU Qiaoqiao¹, SONG Shuqin², ZHAO Kunpeng^1*, LIANG Maojing³

1. School of Civil Engineering, Shandong Jiaotong University, Jinan 250357, China;

2. Jinan Jinyue Highway Engineering Co., Ltd., Jinan 250101, China;

3. Heze Transportation Investment Development Group Co., Ltd., Heze 274000, China

Abstract: To analyze the shear resistance performance of the existing old hollow slab beam bearing shear zone, to ensure the safety and durability of the bridge, considering the factors such as the section form of the slab beam, the layout of ordinary steel bars, the arrangement of prestressed steel bars, the strength of concrete materials, and the combination of load effects, the software MIDAS CIVIL is used to design hollow slab beams S1 and S2 according to Code for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts JTJ 023-1985 and JTG D62-2004, and to perform shear analysis under static loads and moving loads; according to the scale ratio of 1:4, experimental beams T1 and T2 are designed and manufactured according to the requirements of JTJ 023-1985 and JTJ D62-2004, and loaded in a stepwise manner to the normal service limit state and ultimate limit state design loads specified in JTJ D62-2004 until the failure of the experimental beams. Research on the shear resistance performance of the hollow slab beams designed according to JTJ 023-1985 and JTJ D62-2004 under the lane load effects specified in Specifications for Design of Highway Reinforced Concrete and Prestressed Concrete Bridges and Culverts (JTG 3362-2018), and comparison of the results of finite element model analysis with the results of scaled model loading tests. The results show: 1) Under constant load, the shear force on S1 is generally slightly smaller than S2, the maximum shear stress of hollow slab beams S1 and S2 increases significantly with the increase of the combined effect of lane load in JTG 3362-2018, by 26.8% and 16.8% respectively. 2) The experimental phenomena of beams T1 and T2 are similar: As the load increases, cracks appear successively at the loading point bottom plate, pure bending zone bottom plate, and shear compression zone, the inclined cracks in the shear compression zone extend as the main cracks, secondary cracks appear near the main cracks, and transverse cracks at the loading point extend to the web plate. 3) The deflection of beam T1 is greater than that of beam T2. 4)At the beginning of loading, the relationship between the main tensile strain and the load is roughly linear. As the load increases, the main tensile strain in the midspan increases the fastest, followed by the bottom, cracks first appear in the shear compression zone in the middle of the beam, extending to the bottom, the top main tensile strain changes less; the later stage has a larger slope, when the load slightly increases, the strain increase is too fast, and the crack changes greatly. 5)Beams T1 and T2 have not reached the failure state when loaded to the design carrying capacity limit state in JTG 3362-2018, the overall safety margin of the slab beams meets the requirements, but the margin is small. 6)The deflection and strain verification factors of beams T1 and T2 meet the requirements, but early appearance of cracks in the shear zone will directly affect the durability of bridge usage and reduce the overall stiffness of the bridge.

Keywords: bridge engineering; shear-resistant; hollow beam in service; contrast test