首页|间距对公铁双幅主梁气动特性影响的试验研究

间距对公铁双幅主梁气动特性影响的试验研究

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为研究间距对非对称公铁双幅主梁气动特性的影响,以某大跨度公铁双幅斜拉桥主梁断面为背景进行节段模型风洞试验,在间距L/Br=0.2～2.0范围内,测试了2种不同来流方向下双幅主梁的气动特性,分析非对称双幅主梁气动力系数、表面风压分布并推断主梁周围绕流特征,明确间距对非对称公铁双幅主梁气动干扰规律的影响规律.结果表明:无论风向角α=0°或α=180°,上游主梁气动力系数、表面风压分布和绕流方式受间距影响程度相对较小,与单幅主梁气动特性和绕流方式相似;但下游主梁气动特性受间距影响较大,且完全不同于单幅主梁,间隙处的绕流形式随间距的增大而发生变化,下游主梁气动力系数、平均风压系数曲线和脉动风压曲线也表现出完全不同的规律;且间距越大,下游主梁气动特性和绕流方式越接近于单幅主梁.公路主梁的流线性相比于铁路主梁更强,这种气动外形差异导致2种来流方向下非对称双幅主梁气动特性和绕流形式不同,间距在L/Br=0.2～2.0范围内,气动干扰对其影响规律也完全不同.如α=0°时,双主梁上表面始终为"单一钝体流态";但α=180°时,双主梁上表面属于"剪切层附着流态",间距不同,上游公路主梁尾流附着于下游铁路主梁的位置不同,据此可再细分为2种不同的绕流方式.研究成果可为同类型非对称双幅桥梁间隙距离设计提供参考.
Experiment study on spacing effect of the aerodynamic characteristics of twin parallel decks for rail-cum-road bridges
In order to study the spacing effect on the aerodynamic characteristics between the asymmetric parallel girders of rail-cum-road bridges,the wind tunnel test with twin asymmetric section models was carried out on the background of the main beams of a long-span twin asymmetric parallel girders of rail-cum-road bridge to study the aerodynamic characteristics,the wind pressure distribution and flow characteristics of the highway and railway girders under different wind directions in the spacing range of L/Br=0.2～2.0.The results show that regardless of α=0° or α=180°,the aerodynamic coefficient,surface wind pressure distribution and flow pattern of the upstream girder are less affected by the spacing,which is also similar to that of a single girder.However,the aerodynamic characteristics of the downstream girders are greatly affected by the spacing,and are completely different from that of a single girder.The flow pattern around the gap changes with increasing spacing,and the aerodynamic coefficient,mean wind pressure coefficient curve and fluctuating wind pressure coefficient curves of the downstream girders for highway and railway also show completely different laws.The larger the spacing,the closer the aerodynamic characteristics and flow pattern are to that of a single girder.Highway girder has stronger streamlines than railway girder.This difference in aerodynamic shape leads to different aerodynamic interference characteristic of twin asymmetric girders under two opposite wind directions,and the influence of spacing on them is completely different.For example,when α=0° and L/Br=0.2～2.0,the flow pattern for the upper surface of the whole girder is"Single-body regime",but when α=180°,the flow pattern for the upper surface of the whole girder is"Reattachment regime".Depending on the spacing,the wake of the upstream highway girder is attached to the downstream railway girder in different positions,which can be subdivided into two different flow modes.This study can provide reference for the spacing design of the same type of twin asymmetric parallel decks bridge.

spacing effecttwin asymmetric parallel decksrail-cum-road bridgesaerodynamics interferencewind pressure coefficientwind tunnel test

刘路路、何旭辉、邹云峰、杨甲锋

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中南大学 土木工程学院,湖南 长沙 410075

轨道交通工程结构防灾减灾湖南省重点实验室,湖南 长沙 410075

间距效应 双幅桥 公铁平层桥 气动干扰 风压系数 风洞试验

国家自然科学基金国家自然科学基金国家自然科学基金湖南省自然科学基金湖南省科技创新项目中央高校基本科研业务费专项中南大学项目中央高校基本科研业务费专项中南大学项目

52078504U1934209519258082022JJ100822021RC3016CX202202382022ZZTS0152

2024

10.19713/j.cnki.43-1423/u.T20231003

铁道科学与工程学报
中南大学 中国铁道学会

铁道科学与工程学报

CSTPCD北大核心EI
影响因子：0.837
ISSN：1672-7029
年,卷(期)：2024.21(4)
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