桁式钢管混凝土拱桥面内极限承载受力研究

以4管桁式钢管混凝土拱桥为实例,采用弹塑性大变形计算理论,对拱桥面内极限承载受力全过程进行研究。对拱肋失稳形态和拱肋竖向位移、轴力、弯矩的发展等方面作了比较。最后对钢管混凝土拱桥设计规范(修订稿)中的简化计算方法进行了讨论。     

双跨钢管高强混凝土拱桥模态分析与对比

为了获得钢管高强混凝土拱桥的和振型特征,文中以某双跨拱桥为例,通过改变拱肋中混凝土强度、钢管厚度、径厚比等参数,分析其对钢管混凝土拱桥的刚度及自振频率的影响,明确混凝土强度及拱肋钢管厚度对固有频率及拱肋位移的影响规律.结果表明拱桥最大竖向振动频率与最大水平振动频率均小于人体感知范围,振动发生时并不会使人感觉到有明显的振感.拱肋、桥面系的平面内刚度大于平面外刚度,拱肋和桥面系的平面内弯曲变形出现的时间较晚.拱肋中混凝土强度的增加对拱肋刚度的提高并不明显.随着钢管厚度的增加,拱肋的延性和拱桥的竖向刚度逐渐提高,但钢管厚度过大会不利于拱桥的整体稳定性.钢管径厚比的增大有利于提高拱肋的平面外刚度及拱桥整体的竖向刚度.为进一步开展拱桥的动力响应分析奠定基础.     

双肢哑铃形钢管混凝土灌注方案比较

以某双肢哑铃形钢管混凝土拱桥为计算模型,用有限元软件模拟了三种钢管拱肋混凝土灌注方案下的拱肋应力和位移,识别出钢管混凝土拱桥灌注最优的方案及最不利情况,从而在量化的基础上有针对地对钢管混凝土拱桥进行施工方案优化研究。     

青干河大桥主拱空管吊装过程的索力逆分析和优化

钢管拱肋空管的吊装是钢管混凝土拱桥各个施工工序中最为关键的工序 ,它影响着钢管混凝土拱桥成拱时的线形质量。通过对三峡库区青干河大桥的监测监控实践和有限元分析程序 ,就钢管拱肋的吊装过程进行静力逆分析 ,计算扣索索力的变化规律 ,再运用遗传算法优化方法 ,寻找在各个拱肋空管吊装施工过程中能满足施工预拱度的索力值 ,并使吊装合拢时各组扣索索力相差尽可能小     

钢管混凝土拱桥拱肋施工线形控制技术

拱肋线形控制是钢管混凝土拱桥施工中的重要环节,关系到成桥后结构的线形和内力是否满足设计要求。本文以某下承式钢管混凝土拱桥为工程背景,通过有限元数值计算模拟了施工过程中拱肋的受力变形,提出了钢管拱在加工、吊装定位以及拱肋混凝土灌注等各施工阶段拱肋的线形控制技术。     

钢管混凝土桁架拱桥施工阶段应力和位移的有限元分析

文章以某219m跨径的钢管混凝土桁架拱桥为例,首先利用有限元软件Midas/civil建立了2种FEM模型,然后根据现场施工方案将整个施工过程划分为13个施工阶段,并利用Midas/civil分析得到不同施工阶段钢管混凝土拱肋的应力与位移变化规律。结果表明:钢管混凝土拱肋所承担的弯矩值较小,即钢管混凝土拱肋总体处于受压状态;最大应力和位移均可满足设计要求,从而验证了大桥施工方案的合理性。     

某三拱肋混凝土拱桥成桥状态静力分析

以某三拱肋混凝土拱桥为实例,采用空间有限元分析程序MIDAS/ClVIL建立三拱肋拱桥有限元计算模型,分析拱肋、系杆梁等主要构件的受力与变形性能。计算结果表明:拱桥各构件的受力与变形基本关于跨中对称,两侧边拱肋基本关于中跨拱肋对称,但是中间拱肋的变形明显要大于边拱肋;拱肋、系梁总体处于受压状态;全桥以竖向位移为主,最大竖向位移发生在拱顶,系梁竖向位移较小。     

钢管混凝土拱桥拱肋的研究

根据已建钢管混凝土拱桥的拱肋形式，构造了两座400m跨度，宽27．5m的钢管混凝土桁式拱桥，分析了其静力、动力特性，并讨论了拱肋刚度和含钢率对力学性能的影响，为大跨度钢管混凝土拱桥的拱肋形式的设计提供参考。     

TMD对大跨钢管混凝土拱桥的减震性能研究

以某单拱肋钢管混凝土拱桥为原型,通过Midas软件对其有限元模拟并进行动力分析得到该拱桥的动力特性。根据分析结果在主拱肋顶部拟安装TMD系统,分别按照主结构无阻尼和有阻尼两种情况研究该TMD最优参数的取值。对比布置所求参数的TMD前后该拱桥主拱圈顶部在三种不同地震波作用下的位移反应,分析该TMD装置对该拱桥的减震性能。     

钢管混凝土拱桥稳定性影响因素及敏感性研究

通过对某钢管混凝土拱特大桥进行有限元分析,不断改变桥梁结构各部分的刚度、结构形式,分析影响钢管混凝土拱桥稳定性的各因素及敏感性。结果表明:提高拱肋刚度、风撑刚度、风撑形式、吊杆刚度、主梁刚度等均可以提高钢管混凝土拱桥的稳定性;钢管混凝土拱桥稳定性对风撑形式最为敏感,拱肋刚度次之,吊杆刚度最不敏感;采用K字撑是提高钢管混凝土拱桥稳定性的有效手段。     

无风撑背靠式钢管拱肋焊接变形控制技术

介绍了韩江北桥无风撑人字形背靠式钢管混凝土拱桥钢拱肋合拢后,通过对钢管拱肋焊接变形有效控制以减小钢管拱肋横向偏位,使其达到了规范允许范围之内。     

钢结构吊装体系平衡状态确定的优化迭代算法

钢结构吊装体系平衡状态确定的难点在于索力如何实现迭代平衡、刚体位移如何消除以及体系的弹性变形如何考虑.根据钢结构吊装体系的受力特性,建立其平衡状态确定的一种力学模型,通过虚加构件的方法来消除体系的刚体位移,以各吊索段内力相等为优化目标,进而构造了其平衡状态确定的优化迭代算法.能够真实地反映吊装体系由不平衡状态转变到平衡状态时其空间姿态和力学状态的演变过程,可有效模拟实际工程中钢结构的吊装.     

基于荷载试验的大跨钢拱桥承载能力评估

为了解大跨钢拱桥的力学特性,评价其实际承载能力,以厦门五石桥为工程背景,对该桥的动静态力学性能进行了有限元数值分析和动静载试验研究.试验与分析结果表明:静载作用下,该桥拱肋、主梁的应力和变形试验校验系数均在正常范围内,弹性工作性能良好,具有足够的强度和刚度;钢主梁剪力滞效应比较明显,顶底板纵向应力沿横断面近似呈V形分布;动载作用下,结构动态放大系数处于正常范围,结构动力性能良好.     

拱肋倾角对刚性系杆拱桥受力性能的影响

采用MIDAS/Civil软件系统,以某跨度为96m的刚性系杆拱桥为例,分两种工况研究了该桥在恒载和恒载+活载作用下拱肋倾角变化对该体系桥梁受力性能的影响。研究结果表明:拱肋倾角变化对其自身变形、应力等受力性能影响较大,对结构动力特性及稳定性影响也较大,对系梁影响相对较小;研究表明:在跨度100m左右的刚性系杆拱桥中,设计时的拱肋倾角取值与施工过程中拱肋倾角偏差值应该控制在-3°～2°。研究结果可为同类型的桥梁设计与施工提供参考。     

钢箱拱肋缆索吊装中几何非线性影响的分析

在钢箱拱肋的缆索吊装中,由于索的垂度效应、大位移效应以及梁—柱效应等几何非线性因素的影响,致使拱肋的位移以及内力与实际情况存在一定偏差。为了减小合龙拱轴线线形误差,确保桥梁结构施工安全,通过考虑与不考虑几何非线性两种情况的分析对比,提出拱肋缆索吊装过程中可视具体情况给拱肋节段赋予一定的预抬量以抵消几何非线性作用使拱肋所产生的下沉量。     

Deduction and use of an analytical expression for the characteristic curve of a support based on yielding steel ribs

The convergence-confinement method (CCM) applies for cylindrical tunnels driven through a rock-mass that is assumed to be subject initially to a hydrostatic stress field. A basic component of the method is the support characteristic curve (SCC), which represents the deformation of the support produced by the load imposed on it; that is, the load that the support must carry for the amount of radial convergence occurred since support installation. The different elements that may constitute the tunnel support (before installing the tunnel lining) are steel arches (also named steel sets or steel ribs), bolts and shotcrete. The corresponding SCC’s have been developed for each of these support elements. However, for steel arches, the expressions proposed assume that the arch behaves as a rigid element, which is certainly the case for some types of arches. An accurate equation of the characteristic curve for yielding steel ribs (YSRs), steel arches with yielding capacity, has not been widely spread. This paper proposes a specific expression for this type of steel arches, capable of explaining the arch behavior which is easily used, as corresponds to the application of the CCM.     

Study on steel box girder bridges partly stiffened by CFT arch ribs

A new type of arch girder bridge, steel box girders partly stiffened by arch ribs, is proposed and the structural characteristic is studied. Arch ribs are concrete filled steel tubes (CFT) which have high resistance against compression and bending. A parametric study is carried out for the arch girder bridge with different ratios of arch span length to arch rise. Bending moment and tensile forces of the girder are largest with the shortest arch span and decrease as the arch span becomes longer. On the other hand bending moments of the girder do not significantly depend on the arch rise. Bending moments and compressive forces of the arch rib have the same tendency as the girder. Safety of the structural members is verified by the limit state design method considering non-linear stress versus strain relations of steel and concrete. Large deformation elastic–plastic analysis is conducted for the basic case of the proposed bridge to clarify the global buckling strength. Three inclined angles of the arch rib plane are assumed as initial imperfections. The larger initial imperfection decreases the lateral torsional buckling strength. Estimated construction cost of the arch girder bridge with steel pipes without concrete filling is 9% higher than that of the basic CFT arch girder case. The pure CFT arch bridge is the most economical and 23% lower than the basic case. However, as the arch rise of this pure arch bridge is higher, its esthetics may be inferior and it also restricts the available aerial space. This study shows that the proposed bridge has sufficient resistance against bending, compression, global buckling and is considered feasible.     

Static analysis of cable-stayed bridge with CFT arch ribs

A new type of cable supported bridge, cable-stayed CFT arch bridge, was proposed and its static strength was studied in this paper. Arch ribs consist of concrete filled steel tubes (CFT). CFTs have high resistance against bending moments and compressive axial forces and are ideal as arch ribs. A cable-stayed CFT arch bridge with a main-span of 300 m was designed and the safety of its structural members was checked by the limit state design method. Large deformation analysis was used to obtain sectional forces. The CFT arch ribs and the steel box girders and towers of the designed bridge satisfied the required safety criteria for ultimate design loads. The applied loads were further increased until the bridge collapsed when the arch ribs buckled. The amount of steel required for the cable-stayed CFT arch bridge was significantly lower than that for the cable-stayed bridge. It has been found that the proposed cable-stayed CFT arch bridge is feasible and potentially economical.     

钱塘江第四大桥拱肋钢锚箱受力分析

吊杆和拱肋之间的锚固区是把桥面荷栽传给拱肋的关键部位，由于锚固区构造复杂，承受较大的局部荷栽，故建立锚固区的实体模型进行有限元分析，得到了锚固区局部的应力，并对钢锚箱与钢管拱肋的连接部位的焊缝进行了疲劳强度的验算。     

开孔工字形钢梁弹性挠曲变形分析

将腹板开孔钢梁的弹性挠曲变形视为完整钢梁的变形和开孔部分梁段附加变形的迭加;对孔洞处的变形建立了刚性臂模型,变形过程中完整梁段部分保持刚体转动。对孔洞处弯曲应力及变形进行了分析,得到了腹板开孔钢梁弹性挠曲变形的计算公式,并举例进行了验证。