摘要
针对传统加固方法在解决大跨径预应力混凝土箱梁桥的开裂和跨中下挠病害不足的问题,提出了斜拉体系加固方法。采用理论计算、模型试验等方法对加固结构体系、关键构造局部受力性能开展了研究,提出了施工过程监控方法及施工质量控制要点等关键技术。结果表明:在不改变原桥荷载的情况下,拉索根数对桥梁结构受力性能影响较大,根数越多,主梁的最大主拉应力会越小,拉索索力越均匀平缓,布索位置显示锚固点均集中在1/3~1/4跨处;拉索静力允许应力值可采用公路矮塔斜拉桥拉索允许应力值的下限值,可通过积累运营期新增拉索在活载作用下的应力幅值数据,进一步确定合理的拉索允许应力值;斜拉索提供的弹性支撑大大改善了主梁受力过程,同时提高了主梁的弹性变形能力和承载能力;张拉过程及破坏试验加载过程中,托架连接位置未出现明显病害,托梁无明显变形情况,说明该传力方式较为合理可靠;发明的斜拉索滑动索鞍和托梁托架等关键构造,可使新增索力可靠地传递到原有箱梁上,并尽量减小不利附加力和局部应力;提出的施工过程监控方法,可将成桥后应力和线形控制在预期目标范围内,保证了施工过程中的安全;制定的专用施工技术规范及专项工程质量检验评定标准,可有效控制工程质量。研究成果已成功应用于东明黄河公路大桥(75+7×120+75) m改造工程中,取得了较好的加固效果,可为类似工程提供参考和借鉴。
In view of the deficiency of traditional strengthening methods in solving the crack and mid-span deflection disease of long-span PC box girder bridges,the cable-stayed system strengthening method is proposed.The local stress performance of the reinforced structure system and key structures is studied by theoretical calculation and model test.The key technologies such as construction process monitoring method and construction quality control points are proposed.The result shows that(1) without changing the load of the original bridge,the number of cables has great influence on the mechanical performance of the bridge structure,the more the number of cables,the smaller the maximum principal tensile stress of the main beam,the more uniform and gentle the cable force,and the anchor points shown by the cable layout are concentrated at 1/3-1/4 span;(2) the allowable static stress value of the cables can be the lower limit of the allowable stress value of the cables of highway low-pylon cable-stayed bridge,the reasonable allowable stress value of the cables can be further determined by accumulating the stress amplitude data under the live load of the newly added cables during the operation period;(3) the elastic support provided by the stay cables greatly improved the stress process of the main beam,and also improved the elastic deformation capacity and bearing capacity of the main beam;(4) during the tension process and the loading process of the failure test,there is no obvious disease at the bracket connection position and no obvious deformation of the joist,which indicates that the force transmission mode is reasonable and reliable;(5) the invention of key structures such as the sliding cable saddle of the stay cable,the bracket and the joist can reliably transmit the new cable force to the original box girder and minimize the adverse additional force and local stress;(6) the proposed construction process monitoring method can control the stress and geometric shape of the completed bridge within the expected target
作者
王来永
张劲泉
武俊彦
徐刚年
WANG Lai-yong;ZHANG Jin-quan;WU Jun-yan;XU Gang-nian(Research Institute of Highway,Ministry of Transport,Beijing 100088,China;School of Civil Engineering,Shandong Jiaotong University,Jinan Shandong 250357,China)
出处
《公路交通科技》
CAS
CSCD
北大核心
2022年第8期101-108,共8页
Journal of Highway and Transportation Research and Development
基金
交通运输部西部交通建设科技项目(2011 318 223 940)。
关键词
桥梁工程
斜拉体系
理论分析
大跨径箱梁桥
试验研究
桥梁加固
bridge engineering
cable-stayed system
theory analysis
long-span box girder bridge
experimental study
bridge strengthening
