翻译1_to.pdf

空间悬索桥斜吊杆安装索缆试验空间悬索桥斜吊杆安装索缆试验 摘要摘要 永江大桥中包含一段有斜缆索的自锚式悬索桥 该桥采用锚固在刚架末端的斜索 面支撑主缆 在主缆的架设过程中 人们预计斜面索会因为相对较大的张角产生侧向位移或 提升现象 人们用相同比例的实物模型试验来测量缆索的位移值 以决定采取相应的措施来 解决这一问题 通过这些试验安排架设斜面上绳索的方案被修正 在尝试 最后的方案在实 桥中得到成功的应用 DOI 10 1061 ASCE 1084 0702 2002 7 5 300 数据库数据库 关键词 桥 悬索 朝鲜 索缆 简介简介 永江大桥包含一跨钢箱梁 一跨刚桁架 一跨悬索桥 悬索桥跨度 550m 采取 斜索面自锚体系 如图 1 自锚式桥主缆锚固在刚桁架上 只有一小部分已经完工 由于 缆索的空间布置形式 在纺丝架缆过程中 主跨的主缆保持竖直 但是在吊杆与主缆相连后 缆索平面会发生倾斜 在成桥状态主跨 边跨的索面都是斜的 悬索桥主缆由 14 股钢绞线 绞合而成 每股包含 480 根直径 5 1mm 的镀锌钢丝 为架设主缆人们采用了可以比平行索 法架设更多股钢丝的空气离心技术 悬索桥在锚固区附近通常采用索鞍来支撑主缆 各股索缆在索鞍处分散开来 延伸出去 由锚固脚或锚槽锚固 同时把索力传到锚固块上 一般来说 索鞍布置在股脚上部以把各索 向下分散开来 为了像图 2 那样把各索合理的分散开来 大桥的悬索跨与其说采用索鞍还不 如说用了倾斜的索箍 与个索连在一起 在水平和竖直方向将缆索对称的分散开来 图 3 所示斜索箍以 16 314 安装 以同主缆轴线张角相适应 为了安放放射钢线 水平和竖直的 定位块布置在各股钢索之间 斜吊杆外侧 斜吊杆由两份构成 顶部和底部 在纺索过程中 索面下部临时固结在刚架上 然后在其上架设钢丝 吊杆的下部有可嵌入钢丝的索槽 索缆 架设完毕后斜吊杆上下部都用螺栓锚固 然后在其自身平衡下 放松刚架的临时固结 悬索桥段的独特之处在于 自锚式体系和其索的空间布置形式 带来一系列的架设问题 在索塔 索鞍处更加突出 为了解决这些问题人们许多按实物尺寸的模型演示试验 试验和 鞍塔处的试验结果 另有文章论述 本文只论述斜索面的试验结果 为了解决架设问题 人 们 提 出 了 好 多 可 替 代 的 架 设 方 案 选 出 最 好 的 用 于 大 桥 住 缆 架 设 图 1悬索桥总览 图 3 锚定处张拉钢丝 问题的提出问题的提出 锚固区是指从斜索面底到半圆形套管的整个区域 如图 5 所示 套管沿主篮轴线对称 布置 由于主缆锚固在刚架上 斜索面到套管的距离相当的小 只有 13 米 而且主索的水 平倾角 16 650 大于竖向 8 76 的倾角 一些套管 例如 8 10 14 号只好安装在主缆轴线 的上侧或偏左偏右 连接套管的索在成桥状态下是弯曲的 而在架设过程中表现出提升和侧 移现象 下面对架设过程中出现的问题进行了细致的描述 钢丝的侧向位移 在典型的地锚式悬索桥中 索鞍放置在套管之上水平 位移非常小在大桥中 14 股缆索 包含主缆 像扇子一样在斜索面上展开 与各自的套管相连 对于这些有水平张角的钢索 斜索面上索的水平弯曲力比竖向弯曲力还大 这就导致了斜索槽侧面钢丝卷起 如图 6 所示 钢丝的提升现象 在成桥状态下 如图 2 所示 各股钢索从斜索面处向外延伸 在竖直和水平两个面内都 是对称的 为了与主缆延伸相适应 面的入口一侧 塔架一侧 是直的 而在出口一侧 套 管一侧 是竖向弯曲的 上面一排的 5 个套管布置在主缆轴线的上方 与这些套管相连的索 在斜索成型后以 4 3811 上扬 在缆索的纺线过程中 斜索底部要与刚架临时固结 然后在其上架索 与套管相连的索 有向上移动的趋势 由于索的抬升趋势 如图 7 所示 朝向索塔一侧的索可以布置在索槽根 部 但是朝向套管一侧的索并不与索鞍底部接触 因此始终得不到支撑 这就要在架设过程 中约束主缆 图 4 竖直和水平方向上的垫片 试验安装与安装次序 14 根主缆的布置形式如图 3 所示 在这些实物比例的模拟试验中 人们对 4 10 号两 根索进行了试验 在纺索过程中人们预计 4 号索钢绞线在斜索面上会出现侧向位移 10 号 索回同时发生侧向位移和提升现象 如图 8 所示 在框架上设置等比例的套管和索槽 套管设置在左侧 人们设计从不同的 方位安装 以演示不同的套管试验 同时用以铸铁制造的中心框架将索槽封闭起来 索槽内 部宽度为 105 斜索面处主缆的倾角及各索的张角与成桥状态保持一致 钢绞线缠绕在套 管上 锚固在用楔子在右侧框架上安装的锚固块上 人们用 343n 的反力张拉缆索 以同纺 索施工中对索的张拉力相同 实桥中每根主缆都有 480 根钢绞线 24 层 每层 20 根 人们对每根索配的钢绞线只 有 100 根 5 层 每层 20 根 先对侧向位移试验然后再对抬升现象试验 本试验以 4 号索进行演示 该索与主缆轴线左侧的套管相连 如图 5 所示 人们估计在 纺索过程中该索会发生侧向位移 以斜索面上的槽来模拟实桥中的索槽 如图 9 所示 在出 口一侧 索槽水平竖直方向都有弯曲 以与两个面内索的弯曲相适应 人们对 几种安装索 的方案进行修正 试验 如有必要 在试验过程中人们对索槽也要修改 图 5马蹄装置 图 6 方案一方案一 采用索缆成型器 大家一致认为 索缆成型器是塔鞍处安装索缆的有效工具 它看起来像个梳子 是一根 内部塞有琴弦一样钢绞线的钢杆 如图 10 所示 将 21 根高强钢丝嵌入 20 根钢绞线中 这 样就与每层上线的数目相同 在缆索架设过程中 索布置在钢丝的接缝之间 本试验中钢索 成型器在斜索面两侧都有布置 试验结果表明 成型器使人们有能力在槽两侧都安装 索槽 内侧的水平弯曲和钢绞线的侧向弯曲却造成了 索槽内部的安装障碍 而且钢索偏向一侧 同时人们发现用手工对张拉过的索重新定位几乎是不可能的 方案二方案二 改变索的安装次序 以空气绞线法架设缆索 索 以其位置被分为 固定索于活动索两种 为了减少索在 锚固段的交叉数量 从索箍到套管 固定索从 槽中心开始安装 活动索从两边开始 因此 斜索面上槽的安装以活动 固定 活动的模式 如图 11 a 所示 图 11 所示的数字代表槽 内索的架设顺序 图7斜吊杆钢筋拉伸 图8建立实验 正如前面解释的那样 钢绞线偏向一侧 如图 11 偏向左侧 这就造成了架设主缆安 装不到位 大家认为通过改变索缆的安装次序可以解决这一问题 各索简单的从左向右架固 定索和活动索之间不留空隙 因此像图 11b 那样 两条活动索紧跟着固定索架设 纺车每 次可以纺两条索 而不是采用活动 固定 活动的安装模式 但是人们仍然发现槽左侧缆索的偏移 抬升现象 工程师设计了一个特制的导索来阻止 缆索的抬升 以保证各索始终在其设计位置 这个装置是一根 95 长的铁杆 安装在一个 与缆索直径 5 1 相适应的高度 在导索的帮助下 第一层索可以很轻松的安装好 但随后 工程师们又发现 在用导索安装第二层索时 第一层索却碍手碍脚 更糟糕的是由于固定和 活 动 索 的 混 合 使 用 人 们 发 现 许 多 索 在 锚 固 区 交 叉 图9 图10成丝机 方案三方案三 用松弛装置降低预应力索的预应力 除了钢丝索平弯之外 人们发现钢索的预加应力会尽量使钢索保持水平 同样造成钢索 布置的紊乱 工程师们认为当索的预加力足够小时人们可以轻易的用手工对其进行控制 安 装 为降低索面的内部应力 人们设计了一个降低索力的松弛装置 如图 12 所示 图12拉伸装置 图13定型装置 人们引入了一个每层可以容纳 20 根索的扣件 作为松弛装置的一部分 一个安置在出 口 套管一侧 另一个安置在槽入口 塔架一侧 与紧线器相连 架设完一层后 槽两侧 的索也架设好了 并由这个紧线器来支撑 这样就可以通过调整 紧线器来调整降低索的预 加应力 试验结果显示 人们可以通过缩短紧线器间的距离来降低索力 但是索槽内部 索的长 度并没有减少 它们很自然的开始下催 结果是安装索草几乎是不可能的 尽管第一层索可 以安装得很合适 为安装第二层索移动紧线器时 安装工作很容易受阻 图14布置钢丝的夹具 图15钢丝布置 方案四方案四 形状保持装置 到目前为止 人们发现的架设问题的一个是 怎样在架设新一层索缆时保持以架设索缆 不发生位置变化 在方案四中 人们采用如图 13 所示的 绑扎用铁丝 热处理的钢条 3 厚 25 宽 还有索夹来布置缆索 以保证随后架设过程中先前架设的不发生位置改变 有必要的话 人们可以切断斜缆索槽的侧壁来安放这些设备 为锚固钢杆和夹子人们把螺纹 钢筋也焊到了槽底和侧壁上 在纺缆过程中以架设的索被绑扎钢丝临时连成一列 该施工阶段不但用到了绑扎钢丝 还用到了索夹 来保持索始终在其设计位置 如图 14 所示 新的缆索纺完后 夹子绕着螺 纹锚具旋转 打开然后将个股钢丝放置进去 第一层索安装完毕后 人们便将绑扎钢丝移走 靠手工和木锤布置缆索 同时另添加两个装在侧壁的夹子来压紧第一层索 型索夹 安 装完毕后 侧壁开口处的钢杆被锚固到斜索底部 同时将 型夹子移走 在假设第二层索的过程中人们用钢杆来维持个索的布置 第二层索被架设在钢杆上 钢 束像第一层索一样被纺起来 然后固定在 型索夹下面 架设完毕后两层间的钢杆被抽出来 重新安在第二层上 此工艺流程循环进行 直到架设完毕 索槽内部通道宽 105 比索层厚度 5 1 20 102 要大 奇数层的缆索从索槽的 右侧壁开始安装 偶数层的索从左侧开始安装 因此 新一层的缆索被安放在以架设好的钢 绞线之间形成的凹槽处 如图 15 所示 人们发现由于索的平弯 偶数层索倾向于滑向左侧 从而到了以架设好索的顶部而不是在凹槽之中 为了阻止这种现象发生 人们在索槽侧壁和 左弯较多的索之间安了一块 3 厚的垫板 图17 试验结果试验结果 经过这一系列的试验 人们发现方案四是解决安装缆索过程中发生侧向位移的理想体 系 安装完每一层后工程师都要测量其高度与理论高度值相比较 从表 1 的比较中我们可以 发现随着层数的增加实际与理论高差越来越小 而且左侧发生偏移的一边反而比右册侧还高 些 试验的另一个重要因数是安装个索所需要的时间 人们用纺车把揽索从一个锚固区牵引 到另一个锚固区所需要的时间大约是 15 分 20 秒 为了不影响纺线 各层必须在这段时间内 完成 这一点人们还是很自信的 因为从表 1 得到的试验数据 时间为从 14 分 23 秒到 12 分 40 秒 小于纺丝所需要的时间 图18出口处钢筋布置装置 抬升试验 工程师取预计会发生抬升现象并伴随侧向位移的 10 号索作为试验对象 容纳 10 号索的 索槽采用铸铁作成 安装是采用与主缆相适应 16 2414 如图 16 所示 为与主缆的张角相 适应 10 号索槽在水平和竖直面内都有弯曲 而且人们专门设计了一个架设在地面上 450 的水平缆索定位架 人们用它在斜缆索内部将个条索分隔开来 在试验中人们先预计一个 量值然后与分析后的实际数值想比较再设计控制抬升与布索方案 试验程序与结论试验程序与结论 最初设计用来阻止先前试验缆索侧向位移的钢杆和夹子同索槽连在一起 两者都是通过 将缆索压向索槽底部来保持以架设缆索的位置 如有必要可以切断斜索面槽的侧壁来安放钢 杆 夹子 正如预计的那样 由于斜索面的竖向弯曲和抬升 钢索只与底部部分相接触 如图 7 所示 尽管用钢杆 夹子可以向下压人们仍然发现第一层和与底版之间有一条很大的缝隙 在水平索缆定位器末端附近 由于缝隙的存在在加上索缆的纵向向上移动 钢杆甲子并不能 将索缆有效的压回底部 这样钢索变得紊乱而无法安装 人们吊杆内部引入了一个木制的垫板 索槽外侧布置一对钢杆来帮助钢索安装 如图 17 所示 木制的垫板被安装在水平索缆定位器末端来填充索缆与槽底的空间 它支撑着架 设好的索缆 被工程师用做抵抗钢杆传来力的平面 在实吊杆中水平垫板被延伸到 815 长 如图 18 所示 安装在吊杆外侧的钢杆 索夹同样阻止索缆变得紊乱 在成桥状态下 低一 些支架的架设高度要与第一层索缆的布置高度相适应 索架在支撑杆顶部 而且每一层架设 完毕后 缆索保持在上下两杆之间的设设计位置 控制抬升的钢杆与索夹的施工工序与控制侧向位移的极为相似 索同样架在钢杆顶部 夹限制缆索位移 每层架完后人们将钢杆抽出 在架在刚安好的缆上 放松索夹 架好 如 此重复施工直到完毕 为测试体系的有效性 工程师测量架好索的高度 与理论值比较 结果总结在表 2 中 同样的测试架设索缆所需要的时间 表 2 中的结果显示 实际层高与理论层高从第二层开始 不同 而且随层高加大 架完第十层 偏差以达 4 但偏差并不显著增加 表 1 所示 10 号索实际与理论偏差略大于 4 号索 由于 10 号索还发生抬升 4 号索只有 侧向位移 如前所示 纺车从一个锚固区移到另一个大约要 15 分 20 秒 随层数增加架索时间减少 到第十层时只要 13 分钟左右 因此不会影响防线作业 结论 工程师们估计 悬索桥架设过程中会发生吊杆侧向移动 垂直移动 与设计位置偏离 通过一系列的试验 修正 尝试 工程师发现钢杆与索箍组合体系最为有效 一些细节问题 如垫板长度等也得到检验 该体系在实际桥中得到成功应用 Cable Eraction Testat Splay Band for Spatial Suspension Bridge Heungbae Gil MASCE AND Youngjae Choi Abstract The Youngjong Grand Bridge include a self anchored suspension bridge with inclined cable planes The bridge use splay band cable collars to flare the main cable at anchorage which is located at the end of a stiffing truss During the cable erection some ofthe wires at the splay band were expected to experience lateral displacement and or lift phenomena because of the large flare angles at the splay band mockup cable erection test at the anchorage were carried out to find the degree of displacement of wires and to determine appropriate measures to deal with these problems through these problems Through these tests method to arrange wires at the splay bands were devised and tried and select methodwas successfully used for actually bridge DOI 10 1061 ASCE 1084 0702 2002 7 5 300 CE Database keywords Bridges suspension Korea Cables Introduction The young jiong Grand bridge consists of a steel box girder span a truss span and a suspension span Gil and cho1998 The suspension span 550m is a self anchored suspension bridge with inclined main planes Fig 1 Self anchored suspension bridge have the main cable anchorageat the Stiffing truss and only a limited number of them have been built ochsendorf and biillington 1999 Due to the spatial layout of the cable the main cable plane of the main span is vertical during the cable spinning But the cable planes become inclined as the hanger ropes suspender are linked to the main cable In the completed state the cable planes of the main and side spans areinclined The main cable planes of thesuspension have 14 strands each ofwhich Is composed of 480 galvanized parallel wires with a diameter of 5 1mm theairspinning method which can have more wires per strands than the parallel wire strand method is used to erect main cables The typical suspension bridge usesplay saddles to splay the maincable near the anchorage The strands diverging from the splay saddles are flared and anchored to strand shoes or sockets and transmit the cable forces to anchor block In general the splay saddle is placed above the strand shoes or socket and spreads the cable downward To flare the main cable as showninFig2 the suspension span of the Grand Bridge has a splay band cable collar rather than a splay saddle The splay band binds and then spreads the cable symmetricallyinthe vertical and horizontal plane The splay band showninFig3 is installed with an angle of 16 314 which correspond to the angle of the main cable centerline To accommodate the flare vertical and horizontal spacers showninFig4 are placed between the strands at the exit side of the splay band thesplay band composed of two parts thetop and the bottom during the cable spinning the bottom of the splay band is temporarily fixed to the stiffing truss and wires are erected on it the bottom has rectangle grooves to house the strands after completion of the cable erection the top and bottom ofthe splay band are fastened by bolts and then the bands are released from the stiffing truss and equilibriumintheair Theunique features of thesuspension span the self anchored and spatial cable layout posecable erection problems which are most prominentinthe tower saddles and at the splay band Mockup erection test were performed to deal with these problems The problems of and the results of the mockup tests at the tower saddle are dealt withinan other paper gil and choi2002 this paper presents the results ofmockup tests at the splay band A few alternative proposals were suggested to deal with the erection problems and the optimal alternative was selected and used for erection of themain cables of the Grand Bridge Problem statements The anchorage zone refers to the zone from the splay bands to the semicircular strand shoes as showninFig 5 the strands shoes are symmetrically distributed around the main cable centerline since the main cable anchorage is located at the stiffing truss Thedistance between the splay band and the strand shoes is rather short 13 0m Furthermore the horizontal flare angle of the cable 16 65 is larger than the vertical flare angle 8 76 Some strand shoes for example Nos 8 10 and 14 are located above and or the left right of the centerline The strands linked to these strands bend at the complete state and showed lift and or lateral displacement phenomena during cable erection A detailed description of the cable erection problem is given below Lateral displacement of wires In a typical earth anchored suspension bridge the splay saddle is placed above the strand and the horizontal flare is rather small Therefore the wires at splay saddle bend downward and there is little horizontal movement of the wires In the Grand Bridge 14 strands composing a main cable fan out from the splay band and linked to the respective strand shoes for the strand that have horizontal flare angles the horizontal bending force of the wires at the splay band is higher than the vertical bending force This cause lateral displacement shift and pilling up of wires on the side of the splay band channel asshowninFig6 WIRE LIFT In the complete state the strands as showninFig2 are symmetrical flare out from the splay band invertical as well asinhorizontal plane To accommodate the flare of the main cable theband at the entrances pylon sides is straight but has vertical curvatures at the exit strand shoe side The five strand shoes of the upper row Fig5 are placed above the main cable centerline and the strands linked to these shoes bend upward with the angle of 4 338 after leaving thesplay band at thecomplete state During cable spinning the bottom of the splay band is temporarily attached to the stiffing truss and the wires are erected onit strands linked to the upper strand shoes tend to move upward Because of this phenomena wire lift showninFig7 thewire toward the main pylon can be laid on the base of the band channel but the wire toward the strand shoes do not contract the base of the sadldle and therefore remain unsupported this requires restraining of the wires during erection Test setup and procedure The arrangement of 14 strands at the splay band is showninFig 3 In the mockup test the wire arrangement of two strands Nos 4and 10 were tested During cable spinning the wires of the strand NO4 are expected to be displaced laterally at the splay band and those of NO 10 are expected to show both lateral displacement and lift Amockup strand shoe and splay band channels are placed on the frames as showninFig8 and the mockup strand shoe was placed on the left itwas designed to be fixed at different position to model different strand shoes to be tested The center frame housed the full scale splay band channels which are made of cast iron The interior width of the channel is 105mm themain cable angles at the splay band and flare angles of the strands were kept the same as those of the real bridge and the wires were looped around the strand shoes and anchored plate placed on the right frame using wedges The wires were tensioned using a 343N countering weight which corresponded to the cable tension during cable spinning Each strandinthe real bridge has 480 wires 20 wires per x24 layers In the mockup test the fewer than 100 wires 20 wires per layerx5layers were erected for each strand the lateral displacement of wires at the splay band was investigated first after which thelift wasperformed Lateral displacement The test was performed using strand NO14 which was linked to the strand shoe located to the left of the centerline Fig5 Its wires were expected to be displaced laterally during cable spinning The splay band channel that stimulated thegroove of thesplay band is showninFig 9 Thechannel has horizontal and vertical curvatures at the exit side to accommodate flaring of the strandinboth planes several schemes to arrange the wires were devised and tried The modification to splay band channel weremade during the tests if necessary PROPOSAL 1 Wire Formeruse A wire former proved to be an effective tool for the arrangement of the wires at the pylon saddle of the Grand Bridge Gil and Choi2001 The wire former which look like somewhat a comb is a steel bar with inserted piano wires were inserted to house 20 wires which is equal to the number of the wires to each layer During cable erection the cable wires were placedinthe slots between piano wires Wires formers were placed at both ends of the splay band channelinthis test the test results showed that the wire former enable the arrangement at both end of the channel At the inside of the channel however the arrangement was disturbed and the wires shifted to one side of due to the horizontal curvature of the channel and the lateral bending of the wires it was also found that realigning the shifted wires by hand was almost impossible dueto thewire tension PROPOSAL2 Change of Wires layout order Inairspinning method of cable erection The wires are classified into dead wire and live wire depending on the position of the wires To minimize the number of wire crossings tangling at the anchor span from the splay band to the strand shoes the dead wires are laid from the sides therefore the wires at the splay band are arrangedinthe live wire dead wire live wire pattern showninFig11 a The numberinFig11 represent the erection order of the wires inside the channel As explainearlier the wires moved to one side The left sideinFig 11 which caused disarrangement of the erected wires It was thought that these problems could be dealt with by changing the layout order of the wires the wires were simply placed from left to right without distinction between dead wires or live wires Thus as showninFig11 b two live wires were followed by two dead wires the spinning wheel carried two wires at a time rather than the live wire dead wire live wire patten However itwas observed that the wires still shifted and piled up at the left side of the channel A special wire guide was devised to prevent wire piling and keep the wires at the desired position This device is a 95mm long metal bar which is fixed at a height corresponding to the diameter of one wire 5 1mm With the help of this guide the arrangement of the first layerwire can be easily finished However itwas found that the arrangement of the first layer was easily disturbed when the guide was removed to erected the second layer Furthermore lots of wires crossings tangling wereobserved at theanchoragezone due to the mixture of the dead and the live wires PROPOSAL3 Tension reduction by Slacking Device In addition to horizontal bending of the strand wire tension was observed to cause the wire disarrangement asittried to straighten the wires It was thought that the wires could be easily managed and arranged by handifthe wire tension at the splay band is low enough to reduce the wire tension inside the splay band a tension reduction slacking device was devised as shownin Fig12 As a part of the slacking device a specialfastener that can hold one layer of 20wires was introduced One fastener was fixed at the exit side strand shoe side of the channel and the other was placed at the entrance side pylon side and connected to a turnbuckle After a layer was erected wires at both ends of the channel were arranged and held by the fasteners Wire tension inside the band could be reduced by adjusting theturnbuckle Test resuts showed that the tension ofthe wire inside the splay band could be reduced by decreasing the distance between the fastener However the length of wires inside the channel was not reduced and the wires simply started to sag As a result arranging the wires was almost impossible Even f the wires of the first layer was properly arranged The arrangement was easily disturbed when the fastener were removed for theerection of thesecond layer PROPOSA Shape preserving Device One of the erection problem observed so far was how to maintain the arrangement of the previously erected layer during erection of a new layer In Proposal 4tiewires heat treated steel bars thickness 3mm width 25mm and clamps as showninFig13 were employed to arrange the wires and to maintain the arrangement of the erected layers during the erection of a new layer When necessary the sidewalls of the mockup splay band channel were cut out to install the device Toanchor thje bars and theclamps threaded rods were also welded to the channel baseand sidwall During cable spinning the erected wires were