| 预制节段干接缝体外预应力混凝土简支梁抗剪性能试验 |
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| 引用本文： | 姜海波,李宇鸿,肖杰,陈远航,方壮城.预制节段干接缝体外预应力混凝土简支梁抗剪性能试验[J].中国公路学报,2018,31(12):188-195. |
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| 作者姓名： | 姜海波 李宇鸿 肖杰 陈远航 方壮城 |
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| 作者单位： | 广东工业大学 土木与交通工程学院, 广东 广州 510006 |
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| 基金项目： | 广州市科技计划项目（201804010422） |
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| 摘 要： | 预制节段干接缝体外预应力混凝土梁是一种适应于快速化施工的新型桥梁结构形式，然而预制节段干接缝体外预应力混凝土梁的斜截面抗剪破坏机理尚不明确。针对此类状况以文献18]中推荐的箱型截面为原型，进行4根预制节段干接缝体外预应力混凝土梁和3根整体式体外预应力混凝土梁的1：8缩尺模型试验，揭示不同剪跨比（1.5，2.0和2.5）、接缝类型（整体式接缝和干接缝）以及接缝数量（2和4）对预制节段干接缝体外预应力混凝土梁斜截面抗剪性能的影响。在试验过程中观测裂缝的发展，记录体外束应力增量、挠度发展规律、接缝张开情况和破坏形态。试验结果表明：体外预应力预制节段干接缝混凝土梁在键齿处容易产生裂缝；剪跨比是影响节段梁和整体梁抗剪承载力的主要因素，随着剪跨比增大，节段梁和整体梁的抗剪承载力明显降低；在剪跨比小于或等于2.0时，预制节段干接缝体外预应力混凝土梁的抗剪承载力小于相应的整体式混凝土梁的抗剪承载力；根据节段式混凝土梁的接缝是否张开，节段式混凝土梁的受力过程可划分为接缝张开前、后2个阶段；在接缝张开前，节段式混凝土梁的力学行为与整体式混凝土梁的无异；接缝张开前、后，节段式混凝土梁的力学行为发生改变；接缝是控制梁抗剪承载力的主要因素，但接缝数量对节段式混凝土梁抗剪承载力的影响不显著。
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| 关 键 词： | 桥梁工程 斜截面抗剪性能 模型试验 预制节段混凝土梁 干接缝 体外束 快速化施工 |
| 收稿时间： | 2018-07-15 |
Shear Behavior of Precast Concrete Segmental Simply Supported Beam with External Tendons and Dry Joints |
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| JIANG Hai-bo,LI Yu-hong,XIAO Jie,CHEN Yuan-hang,FANG Zhuang-cheng.Shear Behavior of Precast Concrete Segmental Simply Supported Beam with External Tendons and Dry Joints[J].China Journal of Highway and Transport,2018,31(12):188-195. |
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| Authors: | JIANG Hai-bo LI Yu-hong XIAO Jie CHEN Yuan-hang FANG Zhuang-cheng |
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| Affiliation: | School of Civil and Transportation Engineering, Guangdong University of Technology, Guangzhou 510006, Guangdong, China |
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| Abstract: | The precast concrete segmental beam with external tendons and dry joints is a new type of bridge structure suitable for accelerated bridge construction. However, the shear failure mechanism of the precast concrete segmental beam with external tendons and dry joints is unclear. The 1:8 scaled prototypes of the models used in the experiments were determined by referring to the standard sections proposed in "AASHTO-PCI-ASBI Segmental box girder standards for span-by-span and balanced cantilever construction." This study was aimed to investigate the effect of the shear-span ratio (1.5, 2.0 and 2.5), joint type (monolithic joint and dry joint), and number of joints (2 and 4) on the shear behavior of precast concrete segmental beam with external tendons and dry joints. The testing was done on four precast concrete segmental beams with external tendons and dry joints, and three monolithic concrete beams with external tendons. The development of cracks was observed during the test. At the same time, the stress increment in the external tendon, load-deflection relationship, joint opening, and failure pattern were recorded. The experimental results show that the first cracks are observed on the root of keys for precast concrete segmental beams. The shear-span ratio has the principal effect on the shear bearing capacity of segmental and monolithic beams. With the increase in shear-span ratio, the shear bearing capacity of the segmental beam and monolithic beam apparently decreases. When the shear-span ratio is less than or equal to 2.0, the shear bearing capacity of precast concrete segmental beams with external tendons and dry joints is less than that of the corresponding monolithic beams. According to opening of the joint, the mechanical behavior of the concrete segmental beams can be divided into two phases. Before opening, the mechanics behavior of the concrete segmental beam is similar to that of the monolithic concrete beams; after opening, the mechanics behavior of the concrete segmental beams transforms. The joint is the main factor controlling the shear bearing capacity of beams. However, the number of joints in the beam has a little influence on the shear bearing capacity of the concrete segmental beams. |
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| Keywords: | bridge engineering shear behavior model test precast concrete segmental beam dry joint external tendon accelerated bridge construction |
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