先张折线预应力T形梁腹板厚度优化研究  

Study on Optimization of Web Thickness for Pre-tensioned Polyline Prestressed T-Beam

作　　者：张青 魏明光 张炜 ZHANG Qing;WEI Mingguang;ZHANG Wei

机构地区：[1]江西昌铜高速公路有限责任公司,江西南昌330025 [2]上海市政工程设计研究总院(集团)有限公司,上海市200092 [3]江西省交通投资集团有限公司南昌西管理中心信息分中心,江西南昌330009

出　　处：《城市道桥与防洪》2024年第12期97-99,103,M0010,共5页Urban Roads Bridges & Flood Control

摘　　要：先张法预应力T形梁因结构简洁、施工方便、经济性和耐久性好等突出优点逐渐开始在我国的桥梁建设中大规模应用。腹板是T形梁的重要受力部位,是提供结构抗剪的重要部件。根据结构的受力特点,我国传统T梁一般采用变厚腹板的形式,支点腹板厚度一般达到45 cm。然而,美国推出的先张法折线预应力T梁采用等厚腹板的形式,且在支点处的腹板厚度远小于我国T梁腹板。为了探明腹板厚度对桥梁力学性能及经济性的影响,以一座30 m跨的先张折线预应力等厚腹板T形梁为例,对3种腹板厚度进行了空间有限元分析,对抗弯、抗剪、抗裂的关键力学指标和预制梁的经济性进行了分析。研究表明:腹板厚度的变化对荷载效应、承载力、刚度及抗裂性的影响较小,对截面抗剪上限值的影响较大,往往会控制设计。不同设计规范对截面尺寸的限制存在较大差异,采用《公路装配式混凝土桥梁设计规范》(JTG/T 3365-05-2022)以及规范《节段预制混凝土桥梁技术标准》(CJJ/T 111-2023)设计的预制T梁经济性更好。The pre-tensioned prestressed T-beam is gradually and widely used in bridge construction in China due to its outstanding advantages such as simple structure,convenient construction,good economy and good durability.The web is an important load-bearing part of the T-beam and an essential component that provides structural shear resistance.According to the stress characteristics of the structure,the traditional T-beams in China generally adopt a variable-thickness web form,and the thickness of the fulcrum web generally reaches 45 cm.However,the pre-tensioned polyline prestressed T-beam introduced in the United States adopts the form of equal thickness web,and the thickness of the web at the fulcrum is much smaller than that of T-beam webs in China.To investigate the impact of web thickness on the mechanical properties and economics of bridges,taking a 30 m-span pre-tensioned polyline prestressed equal-thickness web T-beam as an example,the spatial finite element analysis is carried out for three web thicknesses.The key mechanical indicators of bending resistance,shear resistance and crack resistance,and the the economics of prefabricated beams are analyzed.The research shows that the change of web thickness has little influence on the load effect,bearing capacity,stiffness and crack resistance,but significantly impact on the upper limit of section shear resistance,often controlling the design.There are significant differences in the restrictions on section dimensions among different design codes.The economy of precast T-beam is better by Code for Design of Highway Prefabricated Concrete Bridges(JTG/T 3365-05—2022)and Technical Standard for Precast Concrete Segment Bridges(CJJ/T 1—2023)during the design.

关 键 词：先张法 折线预应力 腹板 力学性能 经济性 

分 类 号：TU758.11[建筑科学—建筑技术科学] U445.471[建筑科学—桥梁与隧道工程]