单跨大跨度现浇刚构人行桥舒适度分析.pdf

第6 期（总第2 9 0 期）2023年6 月城市道桥与防洪URBANROADSBRIDGES&FLOODCONTROL桥梁结构D01:10.16799/ki.csdqyfh.2023.06.031单跨大跨度现浇刚构人行桥舒适度分析卜江峰（中铁上海设计院集团有限公司，上海市2 0 0 0 0 0）摘要：刚构桥是桥梁设计中较为成熟、应用比较广泛的桥型，但一般情况下，大跨度刚构桥以车行桥为主，很少对人行工况下的舒适度进行验算。目前在城市建设中的大跨度人行桥大多采用钢结构或组合结构桥梁，但是在一些特殊的情况下，现浇结构有其不可替代的优势。以单跨50 m刚构桥为例，介绍了单跨大跨度现浇刚构人行桥的舒适度验算方法，为类似工程提供经验参考。关键词：刚构桥；大跨度；舒适度；人行桥中图分类号：U448.23文献标志码：B文章编号：10 0 9-7 7 16(2 0 2 3)0 6-0 115-0 3钢绞线，腹板钢束合计为12 束，底板为2 束。0引言250为方便行人出行，会在某些重点位置建设人行挑谷桥，综合施工、造价、周边环境等各种因素，单跨大跨165018度现浇梁桥成为相对合适的方案，但桥梁自振频率往往小于3Hz要求。根据国内外设计经验和规范要求，可以对桥梁舒适度进行分析，以评价桥梁方案是否满足人行要求。韩智强等对大跨弯连续刚构桥自振频率计算公式进行了研究和分析。李艺林 2 对考虑桩土效应的刚构桥高墩稳定性和动力特性进行了研究。马信欣 3 对人行天桥舒适度和减振控制进行了分析。上述文献对刚构桥自振频率、钢结构人行桥舒适度做出了详细的阐述和研究，笔者将以实际工程为例，对现浇混凝土大跨度刚构人行桥的舒适度进行分析，总结计算方法和要点，研究结论可为类似项目提供参考。1工程概况如图1所示，拟建桥梁采用1 50 m现浇预应力混凝土门式刚构桥跨越现状V级航道，通航净空为45m5m，主梁总长度50.7 m，计算长度48.6 5m，单箱单室直腹板箱梁，主梁桥面总宽4.5m，净宽3.5m，梁高2.5m，两侧横梁宽2.0 5m。跨中腹板宽0.45m，端部腹板宽0.9 m，跨中顶板厚0.2 m，底板厚0.2 2 m，主梁布置钢束为12-15.2mm预应力收稿日期：2 0 2 2-0 8-12作者简介：卜江峰（19 8 8 一），男，本科，工程师，从事道路桥梁设计工作。55705070V级航道通航孔45000XC0S5110300110520120钻孔灌注桩长40 m号台50桥梁中心线！25,50/451260450图1桥梁构造图桥墩采用矩形实体截面桥墩，桥墩高8.1m，截面尺寸为1.6 5m（纵）3.5m（横），承台采用矩形实体承台，桩基采用直径1.2m钻孔灌注桩，每个承台下布置6 根桩，桩基间距均为3.0 m。2桥梁舒适度分析基本方法人行桥舒适度主要从两个方向分析，即人行荷载的激励作用和结构自身的动力响应。首先通过对行人慢走、正常步行到慢跑、跑步的单足落地曲线进行研究，对单足曲线进行周期性叠加，建立连续行走荷载曲线，并利用傅里叶级数的形式对曲线函数化，具体表达式为：:115.250挑165D2Qd120钻孔灌注桩门长40 m1号台45035050145150城市道桥与防洪F(t)=P1+Z a;cos(2 if,t+,)卜江峰：单跨大跨度现浇刚构人行桥舒适度分析2023年第6 期VRRATIOMNOE式中：P为人的自重；a;为第i阶荷载谐的动载因子；i指第i阶荷载谐波（=1,2,3);f.为步频;t为时间；;为相位角。对于桥梁结构竖向的人行激励，研究表明第一荷载谐波对桥梁的影响占主要部分，对以上公式进行简化后，得出一阶人群荷载谐波余弦函数表达式为：P(t)=P.cos(2 Tf,t)n式中：P为单个人以f,步频行走产生的力的分量；n为加载面积为S的行人流等效人数；亚为落脚频率接近结构固有频率的概率折减系数。将行人连续脚步荷载按以上公式展开后，可知人行桥竖向自振频率的敏感范围为1.2 5 3.0 Hz，侧向为0.51.2 Hz。故对结构自身的动力响应进行分析后，对于常规桥梁可采用避开结构敏感频率的方法进行设计。但对于大跨度人行桥的自振频率往往落在敏感区间，应从加速度的角度，对人致振动舒适度进行评价。3刚构桥舒适度验算采用Midas建立实体模型，全桥共建立单元182个，桩基按实际桩长13m建立，桩底固结，桩基采用等代土弹簧模拟，桩与桥梁承台固接，薄壁墩与主梁和承台固结。刚构人行桥建立实体模型后，对桥梁自振频率进行验算。一阶振形为侧向平动，频率为2.42 7 Hz，避开了侧向敏感区间0.51.2 Hz，横向振动满足舒适度要求。二阶振形为竖向振动，频率为2.9 Hz,位于规范允许的敏感区间1.2 53Hz内（见图2）。根据规范要求，需对刚构桥进行人致振动舒适度验算，本次人行桥舒适度评价等级按CL1等级控制，即人行舒适度达到最佳。3.1人行荷载模型确定通过国内外对行人交通级别和行人密度的研究和总结（见表1），人行桥舒适度验算时，交通级别按D级设计，人群密度d=1.5人/m，即达到行走不舒适，变得拥挤，行人不能自由地选择步伐的特点。本次桥梁人行通道净宽3.5m，桥梁全长50.7 m，桥面面积S=177.45m,桥上总人数n=dS=266.175人，行人流等效人数n=1.85Vn/S=0.17，人的自重P=280 N,f.=2.9 Hzo通过插值，竖向折减系数业=0.143（见图3）。三图2 一、二阶振动模态表1行人交通级别和行人密度交通行人密度d/描述级别(人m-2)A0.2B0.5C1.0D1.5E4.61.0-001.00.2500对以上数据进行代入，并简化公式进行处理后，本次刚构桥桥梁单位面积行人流荷载函数为：116特点舒适而自由地行走，可快步交通十分稀少行走，单个行人能够自由选择步伐行走依然不受限制，快步行交通正常走有时可能被限制行走自由受限，快步行走不交通繁忙可能行走不舒适，变得拥挤。行人交通十分繁忙不能自由选择步伐行人十分拥挤，难以行走，但交通异常繁忙可原地踏步0.50.71.0 1.2频率/Hz(a）侧向1.251.7 2.33.0频率/Hz(b)竖向图3折减系数业2023年第6 期卜江峰：单跨大跨度现浇刚构人行桥舒适度分析城市道桥与防洪P(t)=P.cos(2 f.t)n.Y=280 c0s(2 T 2.9 t)0.143 0.17=6.807 cos(5.8 T t)。3.2桥梁舒适度验算舒适度分析一般为小变形分析，桥梁整体结构处于弹性范围内，因此可以按线性时程分析的方法进行模拟。分析方法采用直接积分法，时程采用瞬态类型，分析时间步长按0.0 1s，分析时间采用50 s。阻尼计算方法采用质量和刚度因子，阻尼比采用0.0 1，通过计算桥梁竖向加速度为0.0 2 41m/s,满足规范中 0,0.2 5f0.78)的要求，满足舒适度CL1级的设计要求。0.02300.0130-0.00650.00300.00450.00250.00050.0015-0.00350.00550.0075+00.20.40.60.84结语对大跨度刚构人行桥的舒适度研究表明，在满足结构受力的前提下，桥梁的舒适度也满足规范要求。在类似工程中，可运用舒适度验算的方法对桥梁结构进行验算，与避让敏感频率的设计方法相比更加科学，更能在一定程度上减少工程造价，具有一定-0.0070-0.017011.21.41.61.822.22.42.62.833.23.43.6时间/s0.0270200:0图4时间函数曲线及加速度时程表的参考意义。参考文献：1韩智强，刘世忠，周勇军，等.大跨弯连续刚构桥自振频率计算公式J.太原科技大学学报，2 0 2 1(4)：2 8 8-2 9 1,2 9 5.2李艺林.考虑桩土效应的刚构桥高墩稳定性及动力特性研究 D.西安：长安大学，2 0 18.3马信欣.人行天桥舒适度与减振控制 D.贵阳：贵州大学,2 0 2 0.90080000100210091008100忆0 0080098008600城市道桥与防洪杂志是您合作的伙伴，为您提供平台，携手共同发展！欢迎新老读者订阅期刊欢迎新老客户刊登广告投稿网站：http:/电话：[phone]联系邮箱：117.Abstract:Cofferdam is widely used as a common temporary enclosure structure in the construction ofmodern bridge foundation pit It is necessary to design and study cofferdam to ensure the safety.The PLC pilecofferdam is used as the water retaining structure of the pier foundation,which not only enhances the watersealing effect of the locked steel pipe pile,but also saves the steel and reduces the construction cost.Takingthe PLC pile cofferdam used in the construction of the main pier of a landscape bridge in Hainan as anexample,the PLC pile cofferdam in the deep foundation pit is analyzed.Combined with the finite elementmethod and theoretical formula,the design scheme is analyzed to ensure the safety and stability of the deepfoundation pit structure in the construction.Keywords:PLC pile;cofferdam;deep foundation pit;finite element analysis;bridgeAnalysis on Comfort Level of Single-span Long-span Cast-in-situ Rigid-frame Pedestrian Bridge.BU Jiangfeng(115)Abstract:The rigid-frame bridge is a mature and widely used bridge type in bridge design.But generally,the long-span rigid-frame bridge is mainly vehicular bridge,and the comfort level under the pedestrianconditions is rarely checked.At present,the steel structure or composite structure bridges are mostly used forthe long-span pedestrian bridges in urban construction.But in some special cases,the cast-in-situ structurehas its irreplaceable advantages.Taking a single-span 50 m rigid-frame bridge as an example,the checkingcalculation method of the comfort level for single-span long-span cast-in-situ rigid-frame pedestrian bridgeis introduced,which provides the experience and reference for similar projects.Keywords:rigid-frame bridge;long span;comfort level;pedestrian bridgeAnalysis on Failure Mechanism of Hinge Joints in Fabricated Hollow Slab Bridges.RAO Ke,JIANG Fuxiang,QIN Yiming（1 1 8)Abstract:Fabricated hollow slab bridges are widely used.The damage of hinge joints is a common disease offabricated hollow slab bridges,and there is controversy over the failure mechanism of hinge joints.Mostscholars believe that the design of hinge joints is defective and the hinge joints are damaged by the crosswisetensile stress.For the investigation of the old bridges,it is found that the proportion of hinge joint failure isvery high,but there is no problem of hinge joints in the investigation of new bridges.If the hinge joints aredamaged,not only the problems of hinge joint exist in the old bridges,but also the failure mechanism of hingejoints has the other important causes.The detailed finite element model is established by using ABAQUSfully to consider the contact between the hinge joint and the hollow slab,and the connecting steel bar betweenthe hinge joint and the hollow slab.It is concluded that the structural stress of the hinge joint is reasonable,inwhich the position of the connecting steel bar is very important.If the connecting steel bar is rusted,the stressof the hinge joint will be defective.Therefore,it is concluded that the disease of the hinge joint is caused bythe corrosion of the connecting steel bar.Keywords:bridge engineering;hinge joint disease;hollow slab;single-slab stress;stressMaterial Selection and Design of Steel Deck Pavement System:.XIE Shengjia,TANG Dongye,CHENG Zhiqiang（1 2 1)Abstract:Combined with the mix design and performance test of pavement materials,the high temperaturestability,fatigue cracking performance and the bonding layer application of the typical pavement materials arestudied and analyzed.The result shows that the epoxy asphalt mixture EA has the better anti-rut features.Its60 f i n a l r u t d e p t h i s a b o u t 3 0%o f a s p h a l t ma s t i c ma c a d a m mi x t u r e.T h e 7 0 f i n a l r u t d e p t h i s o n l y a b o u t