高架桥接触问题的非线性研究进展

随着经济的发展和科技的进步,我国的城市化水平不断提高,但人口的过度集中导致了城市交通拥挤等问题,于是高架桥梁体系日趋完善。因此研究高架桥梁结构间的一系列动力学行为显得尤为重要,特别是在地震作用下的非线性动力相互作用问题。本文首先介绍了高架桥梁结构间接触面问题研究的发展现状,阐述了各种连接单元模型与研究方法,并集中起来进行全面、客观的对比评价,总结了其优点和不足。最后对高架桥非线性接触问题的研究进行了总结与展望。     

地震对桥梁抗震的思考

通过对桥梁抗震理论发展的探讨,结合汶川地震对桥梁破坏情况,阐述了自身对桥梁抗震设计的观点,为桥梁抗震设计提供了参考.     

道桥防水施工路基面处理方法研究分析

道桥防水施工路基面的处理,是直接影响道桥路基面防水层质量和防水层之上的沥青路面铺装层质量的重要因素之一,近几年来越来越受到道桥科研、设计、建造、施工、管理与养护等各方面的重视.道桥路基面防水质量关系到道桥使用的寿命,因为水的渗入会使道桥水泥混凝土里的钢筋锈蚀,导致水泥混凝土胀裂和路桥结构的破坏;而钢箱式桥梁由于水的腐蚀造成钢结构强度破坏更是显而易见.道桥防水层下与道桥路基面粘结,上与沥青路面铺装层粘结,因此道桥防水层与路基面的粘结质量还影响到沥青路面铺装层的质量.我国高速公路和道桥建设飞速发展的二十多年来,高速公路和道桥沥青路面铺装层开裂、起壳等质量问题层出不穷.     

故宫古建筑的防震科学

<正>近日,土耳其发生两次7.8级地震,震级大,破坏力强,导致千年古堡——加济安泰普古堡被毁。从建筑结构角度而言,加济安泰普古堡属于砌体结构,主要特点即以砖石作为建筑核心材料,砖石之间通过砂浆黏结,因而当砂浆受到地震破坏时,易诱发建筑整体破坏。相比而言,木结构建筑以弹性性能良好的木材为核心材料,且拥有平摆浮搁柱根、榫卯节点、斗拱等多种抗震构造,因而能够抵抗较为强烈的地震。故宫便是其中的代表之一。     

多点激励下多跨斜拉桥缩尺模型的地震响应研究.部分2:数值分析（英文）

研究目的:通过非线性动力有限元分析,模拟多塔斜拉桥在多点激励下的地震响应以及揭示其在强震下的倒塌破坏模式。创新要点:解决了多塔斜拉桥的非线性动力数值模拟技术,并首次模拟了多塔斜拉桥在强震下的破坏模式。研究方法:首先采用隐式的Newmark-β法求解多点地震激励下的非线性动力方程(图3),随后采用显式的中心差分格式对强震作用下桥梁的倒塌破坏过程进行数值仿真(图4)。重要结论:1.单主梁模型的数值结果可以很好地反映地震模拟振动台试验的地震响应结果;2.在加速度峰值为4.0 m/s2的El-Centro波时,多塔斜拉桥模型只出现了中塔支座的破坏;3.在加速度峰值为4.0 m/s2的江心波时,多塔斜拉桥模型先后出现了支座破坏、拉索与塔的连接破坏以及中塔上塔柱段的单元失效。     

陕西关中地区农村房屋抗震性能的现状与加强措施

我国是一个多地震国家,近四千年的地震文献记载表明,我国绝大部分地区都发生过震级较大的破坏性地震,地震的发生不仅导致房屋、道路、桥梁等工程结构的倒塌破坏,而且造成惨重的人员伤亡。目前我国农村中的房屋大都采用砖混结构,而且,由于经济的原因,砌体结构中最重要的抗震构造——构造柱、圈梁几乎没有人设置,连砌体结构最基本的抗震构造要求都未达到。2010年利用假期对陕西省中部泾阳县13个镇13乡11562农户的房屋的抗震性能进行了调研。     

抱箍支架法在圆弧形桥墩顶帽施工技术

我国桥梁施工技术不断进步,抱箍支架法被广泛应用于圆形桥墩盖梁或横梁施工中。圆弧形桥墩圆弧长度不同、圆心角角度不同,导致抱箍形式、抱箍受力不同。在天津市津滨轻轨轨道交通工程中,高架区桥梁简支U梁采用圆弧形桥墩,以抱箍支架法在圆弧形桥墩上顶帽施工为背景,详细介绍了抱箍支架法的工艺原理和工艺流程。实践证明,这种施工方法安全可靠,节省施工时间,保证工程质量,值得推广应用。     

浮箱式跨海高架浮桥抗风防浪方法及能力的评估

在所有的自然现象中,地震激励的海啸和风所激励的海浪作用对浮桥的影响最大。因此研究浮箱式跨海高架浮桥抗风防浪能力,是浮箱式跨海高架浮桥能否建成的最重要的因素之一。本文从理论上探讨浮箱式跨海高架浮桥的抗风防浪的方法和能力估算方法。     

多点激励下多跨斜拉桥缩尺模型的地震响应研究．部分2：数值分析

研究目的：通过非线性动力有限元分析,模拟多塔斜拉桥在多点激励下的地震响应以及揭爪其在强震下的倒塌破坏模式。创新要点：解决了多塔斜拉桥的非线性动力数值模拟技术,并首次模拟了多塔斜拉桥在强震下的破坏模式。研究方法：首先采用隐式的Newmark-β法求解多点地震激励下的非线性动力方程（图3）,随后采用显式的中心差分格式对强震作用下桥梁的倒塌破坏过程进行数值仿真（图4）。重要结论：1．单主梁模犁的数值结果可以很好地反映地震模拟振动台试验的地震响应结果;2．在加速度峰值为4．0m／s2的E1。Centro波时,多塔斜拉桥模型只出现了中塔支座的破坏;3．在加速度峰值为4．0m／s2的江心波时,多塔斜拉桥模型先后出现了支序破坏、拉索与塔的连接破坏以及中塔上塔柱段的单元失效。     

带初始裂缝钢筋与混凝土粘结破坏机理

钢筋与混凝土之间的粘结是保障钢筋混凝土结构实现其建筑功能(安全性、适用性和耐久性)的关键影响因素之一.通过实验室模拟不同工作环境中带有不同初始裂缝宽度、以及不同水灰比铰梁试件,经海水浸泡180 d干湿循环或大气环境180 d等环境作用下,对钢筋与混凝土粘结性能进行研究.本文主要分析钢筋与混凝土之间粘结破坏机理.本文试验研究结果表明:(1)钢筋与混凝土粘结破坏主要表现为混凝土沿纵筋方向劈裂破坏(贯穿劈裂破坏和部分劈裂破坏);(2)带预制裂缝试件钢筋与混凝土粘结受预制裂缝的影响,钢筋与混凝土的粘结应力分布改变,钢筋与混凝土的粘结破坏为部分劈裂破坏;(3)如果试件中的钢筋不能提供足够拉力时,会发生钢筋受拉屈服的破坏而钢筋与混凝土的粘结不破坏.     

EFFECT OF CORROSION ON BOND BEHAVIOR AND BENDING STRENGTH OF REINFORCED CONCRETE BEAMS

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FRP加固锈蚀钢筋混凝土梁的受弯性能分析(英文)

采用Ansys有限元软件对8根不同锈蚀率的FRP片材加固钢筋混凝土梁的受弯性能进行数值分析,研究纵筋锈蚀率对FRP加固梁的裂纹开展、破坏模式、承载能力以及延性和变形能力的影响.研究结果表明:低钢筋锈蚀率的梁发生受压区混凝土压碎破坏;中等锈蚀率的梁钢筋屈服后,钢筋与混凝土界面发生黏结滑移,最后FRP剥离破坏;高锈蚀率的梁钢筋没有达到屈服强度便发生黏结滑移,最后发生受压区混凝土压碎破坏.钢筋锈蚀越严重,FRP加固钢筋混凝土梁的承载力降低得越多.试件RCB-1(锈蚀率为0)的承载力为115 kN,而试件RCB-7(锈蚀率为20%)的承载力仅为42 kN.与FRP加固未锈蚀的钢筋混凝土梁相比,FRP加固锈蚀钢筋混凝土梁的变形能力较高.试件RCB-1和试件RCB-7的最大跨中挠度分别为20 mm和35 mm,而试件RCB-5(锈蚀率为10%)的最大跨中挠度达到了60 mm.     

论加快中国文化软实力建设的重大意义

中国拥有丰富的文化软实力资源。她不仅拥有悠久的历史和灿烂的文化,而且坚持社会主义、建立了最高类型的民主价值观、探索出一条不同于西方发达国家的现代化道路,即建设中国特色社会主义的中国发展模式。但是,目前我国文化软实力的建设还处于起步阶段,在文化软实力建设方面还存在一些问题,与世界上其他大国尤其是西方国家相比,还有很大的差距。因此,加快我国的文化软实力建设具有重大的理论和现实意义。     

Reinforcement and numerical analysis on the corbel of a half-through arch bridge

Corbels support the crossbeams of half-through arch bridges. They are prone to cracking easily due to their characteristics and complicated loading conditions. Based on a practical diagnosis of a bridge crossbeam, we bonded steel plates onto bridge corbels to strengthen them. We carried out a numerical analysis on the effectiveness of the reinforcement by using the commercial sof~are ANSYS. The numerical analysis shows that the stresses near the section break increased slightly, but the variation amplitude was small and all the stresses were within an allowable range. The loading test indicates that it is feasible to strengthen the corbel with vertical bonded steel plates. Therefore, the reinforcement is effective and economical. This reinforcement method is suitable for this type of corbel and can be applied in similar cases.     

Numerical Determination of Shear Strength of Steel Reinforced Concrete Column Strengthened by CFRP Sheets

The earthquake-resistant property of reinforced concrete members depends on the interaction between reinforcing bars and surrounding concrete through bond to a large degree,In this paper a general system aimed at dealing with the failure analysis of reinforced concrete columns strengthened with carbon-fiber-reinforced plastic(CFRP) sheets including bond-slip of the anchored reinforcing bars at the foot of the columns is presented.It is based on the yield design theory with a mixed modeling of the structue,according to which the concrete material is treated as a classical two-dimensional continuum ,whereas the longitudinal reinfocing bars are regarded as one-dimensional rods including bond-slip at the foot of the columns,In shear reinforced zones both the shear CFRP sheets and transvers reinforcing bars are incorporated in the analysis throuth a homogenization procedure and they are only in tesion ,The approach is then implemented numerically by means of the finite-element formulation,The numerical procedure produces accurate estimates for the loading-carrying capactiy of the shear members taken as an illustrative application by correlation with the experimental results,so the proposed approach is valid.     

Seismic behavior of specially shaped column joints with X-shaped reinforcement

To investigate the seismic behavior of specially shaped column joints with X-shaped reinforcement,two groups of specimens with or without X-shaped reinforcement in joint core region were tested under constant axial compression load and low reversed cyclic loading,which imitated low to moderate earthquake force.The seismic behavior of specially shaped column joints with X-shaped reinforcement in terms of bearing capacity,displacement,ductility,hysteretic curve,stiffness degradation and energy dissipation was studied and compared to that without Xshaped reinforcement in joint core region.With the damage estimation model,the accumulated damage was analyzed.The shearing capacity formula of specially shaped column joints reinforced by X-shaped reinforcement was proposed with a simple form.The test results show that X-shaped reinforcement is an effective measure for improving the seismic behavior of specially shaped column joints including deformation behavior,ductility and hysteretic characteristic.All specimens were damaged with gradual stiffness degeneration.In addition,X-shaped reinforcement in the joint core region is an effective way to lighten the degree of cumulated damage.The good seismic performance obtained from the specially shaped column joint with X-shaped reinforcement can be used in engineering applications.The test value is higher than the calculated value,which indicates that the formula is safe for the design of specially shaped column joints.     

基于现场实测的某大跨度悬索桥桥址区风场特性

为了对大桥抗风评估提供可靠依据,结合东海某大跨度悬索桥的健康监测系统,同步实测了桥面及桥塔处的风速,采用统计及频谱分析方法对桥面平均风速和风向、风速随高度变化、风速的脉动特性、相关性以及桥面风场的绕流特性等进行了分析.结果表明:加劲梁纵向不同位置处平均风速大小接近,但平均风向差别较大;无量纲幂指数随风速增大呈明显减小的...     

论大连(旅顺)史在中国东北史中的地位

大连、旅顺地处辽东半岛的南端 ,并与山东半岛遥遥相对 ,形成扼守京津塘地区的咽喉要地 ,是古代中原地区联接东北地区的大陆桥。近一百年以来在大连地区发现了众多的考古文化。无论是远古、古代、还是近现代 ,一些重大的历史事件均发生在这一地区 ,并与东北各历史时期有着广泛而深刻的联系。本文试图通过考古发现 ,简述大连旅顺在中国东北地区的历史地位与作用。     

Effect of corrosion on bond behavior and bending strength of reinforced concrete beams

There is growing concern for corrosion damage in reinforced concrete structures with several decades’ service. Pullout tests and beam tests were carried out to study the effect of reinforcement corrosion on the bond behavior and bending strength of reinforced concrete beams. The bond strength of plain bars and concrete initially increases with increasing corrosion, then declines. The turning point depends on the cracking of the concrete cover. The bond strength of deformed bars and concrete increases with corrosion up to a certain amount, but with progressive increase in corrosion, the bond strength decreases, and the cracking of the concrete cover seems to have no effect on the bond strength. On the basis of test data, the bond strength coefficient recommended here, which, together with the bond strength of uncorroded steel bars and concrete, can be used to easily calculate the bond strength of corroded steel bars and concrete. The bond strength coefficient proposed in this paper can be used to study the bond stress-slip relationship of corroded steel bars and concrete. The bending strength of corroded reinforced concrete beams declines with increasing reinforcement corrosion. Decreased bending strength of corroded RC beam is due to reduction in steel bar cross section, reduction of yield strength of steel bar, and reduction of bond capacity between steel bar and concrete. Project supported by Cao Guanbiao Key Technology Development Founding of Zhejiang University and Construction Ministry of China.     

Bond property test of reinforced concrete with all soaking and impressed current method corrosion

In order to research the bond properties between corroded reinforcement bars and concrete, reinforcement bars with different diameters and different types and concrete with different strength levels were treated specially with all soaking and impressed current method, and the bond properties were measured with the pull-out test. The comparative analysis of the bond properties of corroded reinforcement bars was carried out. The results showed that the types of reinforcement bars and concrete had great influence on the bond strength. The corrosion and volume expansion of reinforcement bars made concrete in tensile condition, which tended to produce cracks in parallel reinforced direction. The typical bond failure of plain reinforcement bars was pull-out, while the typical bond failure of ribbed reinforcement bars was split. The bond strength between corroded reinforcement bars and concrete increased with the increase of concrete strength. The bond strength of plain and ribbed reinforcement bars showed a decreasing trend after the first increase with the increase of the extent of corrosion. Through the test, the coefficients of the bond strength of plain and ribbed reinforcement bars were given, respectively.