共查询到18条相似文献，搜索用时 546 毫秒
1.
从工程实例出发,对一座钢管混凝土拱桥建立了有限元模型,从线弹性和几何非线性两个方面进行了数值分析,分析表明该桥的屈曲稳定比较可靠,结构失稳模态均为拱肋面外失稳,表明拱肋的横向刚度相对系梁较弱. 相似文献
2.
黄玉萍 《石家庄铁路职业技术学院学报》2018,(1)
望湖街路桥斜跨拱肋混凝土主梁的组合拱桥,其吊杆是呈空间索面布置。由于该桥的拱肋刚度相对于主梁较弱,拱肋在吊杆不同批次张拉时的受力复杂,吊杆力对拱肋的受力和其他吊杆的受力影响较大,吊杆索力的偏差对整桥的受力特性影响巨大。通过建立有限元模型,对张拉顺序和张拉加载过程进行了精细计算分析,找出了最佳加载顺序,从而使得钢箱拱最终水平位移最小。计算结果具有较强的实用价值。 相似文献
3.
两河口大桥在施工过程中采用了分7段分2层浇注方式,其顺序是先拱脚,再拱顶两侧,然后对称向上浇注,最后封顶。在本施工阶段中确保拱肋的稳定,拱肋各截面的应力不超过允许值,以及保证拱肋线型处在设计和规范规定的范围内是该阶段的施工控制主要目标。施工当时在L/8、L/4、3L/8、L/2处共设置了14个点,以便监测。结果表明:拱顶截面在浇注钢筋砼的施工过程中,在L/2处挠度最大,预计挠度最大值为0.02487m,挠度的产业化幅度也最大,挠度的变化幅值为0.03769m。由此可见,拱肋截面的刚度较大,在浇注砼的施工过程中的变形不大,能够满足施工中拱肋对挠度的要求。拱肋横向轴线偏移量在规范允许值内,拱肋线型在设计规定的范围内,达到了分析、监测及控制的预期目标。 相似文献
4.
两河口大桥在施工过程中采用了分7段分2层浇注方式，其顺序是先拱脚，再拱顶两侧，然后对称向上浇注，最后封顶。在本施工阶段中确保拱肋的稳定，拱肋各截面的应力不超过允许值，以及保证拱肋线型处在设计和规范规定的范围内是该阶段的施工控制主要目标。施工当时在L／8、L／4、3L／8、L／2处共设置了14个点，以便监测。结果表明：拱顶截面在浇注钢筋砼的施工过程中，在L／2处挠度最大，预计挠度最大值为0．02487m，挠度的产业化幅度也最大，挠度的变化幅值为0．03769m。由此可见．拱肋截面的刚度较大，在浇注砼的施工过程中的变形不大，能够满足施工中拱肋对挠度的要求。拱肋横向轴线偏移量在规范允许值内，拱肋线型在设计规定的范围内，达到了分析、监测及控制的预期目标。 相似文献
5.
王天舒 《淮北职业技术学院学报》2009,8(1):22-23
结合安徽铜陵至汤口高速公路太平湖大桥拱肋吊装实例,介绍了该桥拱肋安装技术和拱肋安装过程中测控的内容。采用拱肋安装过程中线形测控、复核调整技术,优化拱轴线线形,确保钢管混凝土拱桥受力最合理。 相似文献
6.
颜桂云 《福建工程学院学报》2012,(1):12-16
为检验在役混凝土拱桥的承载能力与动力特性,对某净跨为134.7m的拱桥进行荷载试验。测试结构静态的应变、桥面挠度、拱肋挠度、吊索变形、吊索索力等结构静力反应。同时,测试了结构自振频率、动挠度及加速度等结构动力反应,根据动挠度计算得出冲击系数。将实测值与理论值进行对比分析。结果表明,应变校验系数在0.7～1.0之间,实测的挠度、吊索索力、频率及冲击系数均小于理论值,说明桥梁具有较好承载力和整体竖向刚度较好。试验方法与分析结果为今后评估与鉴定同类型桥梁提供理论依据和技术参考。 相似文献
7.
以某混合梁斜拉桥为工程背景,分别采用Midas Civil和ANSYS建立全桥空间杆系有限元模型和钢混凝土结合段的精细实体有限元模型,进行最不利荷载组合作用下结构受力性能分析。研究表明:钢-混凝土结合段在最不利荷载组合工况下各组成部分受力均衡、变形连续协调;钢-混凝土结合段的钢箱梁应力满足要求,各钢板无屈曲现象发生;钢-混凝土结合段中混凝土箱梁节段在混凝土顶板与隔板结合部及翼缘倒角位置会出现较大的主拉应力,最大可达到4.84 MPa,超过C50混凝土抗拉强度,建议必要时应增加钢筋用量,进一步优化局部受力。 相似文献
8.
以北海市海景大道工程冯家江大桥主桥100 m下承式钢-混叠合梁简支钢拱桥为施工监控背景,采用了基于物联网及云平台的自动化监测技术,根据现场施工采用主梁拼装滑移施工+主拱肋吊装施工的工法,从施工临时结构的沉降、受力、周边环境、主拱肋风压等多个方面进行自动化监测,取得了较好的效果. 相似文献
9.
在分析闽浙木拱廊桥结构发展背景和营造特点的基础上,总结了国内外对闽浙木拱廊桥木材材性、受力系统、传力机理、节点等方面的研究方法和研究内容。 文献分析表明,廊屋等竖向荷载对廊桥整体稳定有利,但廊桥抵抗横向荷载的能力不强。 该体系中构件受力以轴力为主,各个系统之间相互搭接传力,拥有拱桥的受力特性,是现存廊桥最为成熟的结构形式。 通过综述研究指出闽浙木拱廊桥受力系统和节点是对结构受力性能影响的关键问题,为廊桥的保护修缮和新建改造提供理论依据。 相似文献
10.
以重庆铁路枢纽东环线珞璜南右线特大桥连续梁跨越既有渝贵线铁路工程为依托,研究了转体桥施工力学特性及监控技术.采用Midas civil软件建立桥梁模型,研究转体桥关键工况的力学特性,对比分析了桥梁变形、内力的数值模拟值与现场实测值.结果表明:危险工况中箱梁截面应力最大发生在跨中,其值为12.36 MPa,位移最大发生在8#梁段与9#梁段交界面,其值为26.34 mm.支座及跨中两个位置是关键工况中危险受力处,悬臂根部截面应选为应力监测截面.线形监测表明在转体施工过程中,小里程、大里程侧梁顶标高数值模拟值与实测值差值最大分别为17 mm、19 mm;转体完成拆除支架后,主梁线形变化较大,小里程、大里程侧变化最大分别为16 mm、20 mm.悬臂梁根部应力监测表明,顶板应力值始终大于底板应力值,最大压应力发生在顶板处,其值为8.14 MPa,小于C55混凝土抗压强度标准值,顶板、底板处应力数值模拟值与实测值差值最大分别为0.92 MPa、0.81 MPa.以上均满足设计要求,保证了转体施工安全,为同类型施工提供了借鉴经验. 相似文献
11.
A three-dimensional finite element model was established for a large span concrete filled steel tubular (CFST) arch bridge which is currently under construction. The arch rib, the spandrel columns, the prestressed concrete box-beam, the cast-in-situ concrete plate of bridge deck, the steel box-beam and the crossbeams connecting the two pieces of arch ribs, were modeled by three-dimensional Timoshenko beam elements (3DTBE). The suspenders were modeled by three-dimensional cable elements (3DCE). Both geometric nonlinearity and prestress effect could be included in each kind of element. At the same time a second finite element model with the same geometric and material properties excepted for the sectional dimension of arch rib was set up. Static dynamic analyses were performed to determine the corresponding characteristics of the structure. The results showed that the arch rib's axial rigidity could be determined by static analysis. The stability and vibration of this system could be separated into in-plane modes, out-of-plane modes and coupled modes. The in-plane stability and dynamic characteristics are determined by the arch rib's vertical stiffness and that of out-of-plane is determined by the crossbeams' stiffness and arch rib's lateral stiffness mainly. The in-plane stiffness is much greater than that of out-of-plane for this kind of bridge . The effect of geometric nonlinearity and prestress effect on bridge behavior is insignificant. 相似文献
12.
The key in the force transmission between the tower and the foundation for offshore wind turbines is to transfer the large moment and horizontal loads.The finite element model of a large-scale prestres... 相似文献
13.
采用有限元方法模拟了热载荷下梯度结构硬质合金的弹塑性响应．样品几何模型为二维梯度结构的轴对称圆柱体．通过引入约束因子构建了梯度材料的弹塑性本构方程．数值模拟表明：当材料温度从初始无应力的800℃下降到0℃时,在样品表面出现了压应力而在富钴区出现了拉应力;表面压应力的最大值为254MPa,富钴区拉应力的最大值为252MPa;在钴相浓度差等于或大于0．3时,钴相梯度区出现了明显的塑性流动;当温度从0℃上升到800℃时,总的塑性应变达到0．0014．塑性流动有利于降低材料内部的热应力集中． 相似文献
14.
大型复杂桥梁结构的极限状态函数都是隐式的非线性函数,采用传统的可靠性分析方法可能无法实现,但利用响应面有限元法可以很好地解决这类问题。利用响应面法对一下承式钢拱桥拱肋、主梁在正常使用极限状态下的轴向应力、竖向位移的可靠度进行了分析,并根据拟合出的各极限状态函数显式表达式得出了相应的可靠度指标,说明响应面有限元法是计算下承式钢拱桥构件可靠度的有效方法。 相似文献
15.
以某双塔单索面人行钢斜拉桥为对象,采用Midas Civil建立全桥空间杆系有限元模型,进行恒载、活载和承载能力极限状态作用下结构受力性能分析,同时开展该桥的动力特性分析。研究表明:对于该异形斜拉桥,活载引起的主梁和主塔弯矩效应较恒载作用下的结果更加显著;承载能力极限状态作用下,该桥主梁、主塔、斜拉索等主要承重构件的最大应力均小于材料容许应力,满足规范要求;动力特性分析结果表明主梁面内刚度和主塔面外刚度较小,此外遮阳棚的局部振动在高阶振型中所占比例较大,在地震作用下可能发生破坏;该桥的一阶竖向自振频率为1.92 Hz,不满足现行规范要求,建议采取有效的减振措施来控制人致振动响应。 相似文献
16.
吴继红胡阳 《福建工程学院学报》2020,(4):324-328
针对一座主梁存在裂缝的混凝土独塔斜拉桥,考虑混凝土裂缝对材料本构关系的影响,对设计荷载作用下桥梁的整体与局部响应进行分析以评估其承载能力。结果表明,在最不利的工况中,开裂后主梁顶板、底板和斜腹板、直腹板上未开裂区域的主拉应力和主压应力都小于规范给出的强度标准值;裂缝法向和切向的压应力均小于规范强度标准值,裂缝切线和法线方向的拉应力在局部很小的范围内略高于规范的抗拉强度标准值。开裂区域局部承载力有所降低,但车辆荷载作用下裂缝不会进一步扩展。 相似文献
17.
Zhang YZ Zhou YC Liu L Lu Y Hirofumi Y 《Journal of Zhejiang University. Science. B》2007,8(6):416-421
Objective： There are no detailed reports of three-dimensional measurement of abutment teeth in mastication, because it is knotty to observe the rotation in chewing directly, and inexact to estimate indirectly. This work studies the three-dimensional stability of rigidly fixed bridge under the stresses of distributed loads and concentrated loads by optical method that gives the tip angle and rotation angle calculated directly based on measurement data. Methods： The specimen, taken from a 25-year-old male, was a left mandible without the second premolars and the first molars. As abutments, first premolar and second molar have complete periodontium. The specimen was soaked in formaldehyde solution. The bridge was fixed between two abutment teeth （first premolars and second molars）, and the mandible was cemented in a steel box. The load was increased from 0 kg to 23 kg. Laser holographic technique was used to measure the three-dimensional bit shift of the dens, both buccolingual bit shift and mesiodistal bit shift, and determine tip angle and rotation angle. Results： The effects of stress distribution on the rigidly fixed bridge were evaluated, and stabilization of the bridge under the stresses of distributed loads and concentrated loads, respectively, were analyzed. The results showed that the tips of two abutments were very similar, and no distinct difference was observed between the distributed load and the concentrated load. However, the maximum rotation angle for the distributed load was two to four times as large as that for the concentrated load. In the experiment, the tip angle of the abutment teeth was no more than 0.65 degree, and the rotation angle was no more than 0.60 degree. All maximum angles occurred in the second molar. Conclusion： The fixed bridge is considered to be safe. In addition, a method for measuring the rotation angle was provided effectively. 相似文献
18.
Approach for analyzing the ultimate strength of concrete filled steel tubular arch bridges with stiffening girder 总被引：2，自引：0，他引：2
ZHANG Zhi-cheng XIE Xu ZHANG He CHEN Heng-zhi 《浙江大学学报(A卷英文版)》2007,8(5):682-692
A convenient approach is proposed for analyzing the ultimate load carrying capacity of concrete filled steel tubular (CFST) arch bridge with stiffening girders. A fiber model beam element is specially used to simulate the stiffening girder and CFST arch rib. The geometric nonlinearity, material nonlinearity, influence of the construction process and the contribution of prestressing reinforcement are all taken into consideration. The accuracy of this method is validated by comparing its results with experimental results. Finally, the ultimate strength of an abnormal CFST arch bridge with stiffening girders is investigated and the effect of construction method is discussed. It is concluded that the construction process has little effect on the ultimate strength of the bridge. 相似文献