混凝土结构加固设计程序

内容:混凝土结构加固设计计算软件,它适用的加固方法有加大截面法、外包钢法、预应力拉杆、预应力撑杆加固法、粘钢加固法、增设支点加固法等国内外常用的加固方法。计算的构件类型有受弯构件、轴心受压构件、偏心受压构件。主要计算内容有: (1)、混凝土结构或构件加固前和加固后正截面受弯、受压承载力、斜截面受剪承载力; (2)、采用预应力拉杆、预应力撑杆加固的构件加固配筋计算和拉变形量的计算; (3)、增设支点加固的构件内力分析及截面设计计算。软件计算中通过引入截面组合系数     

建筑结构学报1988年(第9卷第1-6期)目录

赎筑结构的理论研究焊接工形柱承载能力的试验及理论研究钢纤维受弯构件荷载一变形全过程分析新型横配筋砖砌体试验研究采用现场非破损试验方法对砖砌体力学 性能的侧定研究和分析钢筋硷构件的收缩应力与翘曲预应力超静定结构的等效荷载计算预应力硷受扭构件的抗裂度及强度计算网状球壳的连续化分析方法广义位移的有限条法及其在高层建筑结 构分析中的应用井式梁的最大挠度系数夹板墙的试验研究与加固设计钢压弯构件弯扭屈曲的研究网格圆柱扁壳的稳定性硷受拉应力一变形全曲线的试验研究自立式高耸结构抗风可靠性分析的 改进方法加权残值法…     

无碴轨道后张法预应力混凝土简支箱梁张拉伸长值的计算及校核

对钢绞线张拉预应力施加、锚固的方法和张拉力、钢绞线伸长量的理论计算,在相应的规范中都已有规定,但对目前客运专线铁路简支箱梁而言,在实际操作中对钢绞线施加预应力张拉的伸长值、钢绞线锚固时锚具夹片回缩量的量测,各家说法及做法均存在差异,这对预应力张拉质量控制的双控指标（即钢绞线张拉力与实际伸长值）的计算和评判产生了一定的影响。鉴于此,本文结合预制梁的设计基本参数进行了伸长值的理论计算及现场张拉伸长值的量测及计算。同时对预应力筋锚具夹片回缩值的测量及校核也作了一定的分析。     

混凝土梯形构件正截面受弯承载力计算方法

根据文献 [1]矩形构件正截面受弯承载力计算公式及其纵向受拉钢筋截面面积计算方法 ,推导出了混凝土梯形构件正截面受弯承载力计算公式及其纵向受拉钢筋截面面积计算方法 ,并将其受弯承载力计算系数制成了表格 ,可供大家设计梯形梁时使用     

梯形框架转换层内预应力

首先介绍钢混梯框大空间转换层结构体系。再对后张有粘预应力梁、柱控制截面上出现的拉弯、压弯、纯弯状态进行论述。给出预应力与普通钢混构件混合布置又相互约束的计算方法。建立了计算控制应力公式,使普通与预应力两种钢筋同时达到设计强度并在裂缝宽度控制下互补,更适合在构件布置复杂的结构体系中应用。     

预应力轴心受拉钢构件高温性能试验及理论研究

进行了3根预应力轴心受拉钢构件高温试验研究。试验结果表明，高温下预应力轴心受拉构件中内置拉索和钢管所承受荷载比例随温度的变化而不断变化。升温初期拉索张力随温度升高不断增大，预应力轴心受拉钢构件轴向位移平稳发展，在达到峰值后，拉索张力随升温时间的延长而不断降低。在临界状态下，轴向位移增长很快， 预应力受拉构件中拉索均被拉断，外部钢管发生不同程度的颈缩现象。在试验结果的基础上，建立了预应力轴心受拉钢构件的有限元分析模型，得到了高温作用下预应力轴心拉杆中拉索张力和预应力钢杆轴向位移的时程全曲线。参数分析的结果表明：在其他条件相同时，预应力轴心受拉钢构件失效时的临界温度随着荷载比的增加而降低；当预应力比小于08时，预应力比对预应力轴心受拉钢构件失效时的临界温度的影响较小，当预应力比等于08时，预应力轴心受拉钢构件失效时的临界温度显著的提高；在其他条件相同时，预应力轴心受拉钢构件失效的临界温度随约束刚度比的增大而增大。最后对高温下预应力轴心受拉钢构件进行了理论分析，推导出预应力轴心受拉钢构件高温下差分计算方法，并以此为基础编写程序。通过计算结果与试验结果的对比，证明了差分计算方法的正确性。     

关于预应力构件抗裂计算的建议

在进行预应力钢筋混凝土受弯构件抗裂性的计算时,往往认为提高受拉区钢筋的控制应力(σ_0)值,使有效预应力值提高,因而亦使整个构件抗裂性提高。一般说来,这个原则是正确的。但是在按照现行的CH10-57规范进行设计时,有时会出现提高了控制应力值,反而导致有效预应力值及构件抗裂性的     

对受损无粘结预应力混凝土梁检测与有限元分析

北良港某大型无粘结预应力混凝土梁为某立交桥工程中的一跨预制梁,跨度30m且为简支结构,截面形式见图1(对称结构,仅取半跨说明),配有8束曲线型无粘结预应力钢绞线及分布于整个截面上的非预应力钢筋。其中,钢绞线抗拉强度实测值大于2000MPa;梁截面中部的四束钢绞线的截面积均为560mm2,上面和下面四束钢绞线的截面积均为420mm2;各束施加张拉控制应力为1395MPa。非预应力钢筋有一级钢和二级钢两种,分布于整个梁截面上;现场钻芯取样测得混凝土抗压强度为51.6MPa。由于运输过程中梁的一端从运输车上滑落,导致梁侧向受弯,引起梁一侧跨中区域开…     

牛角坪双线铁路连续刚构桥径向力荷载作用分析

建立变截面变高度连续刚构桥计算模型,分析了在变截面梁底板下缘受到预应力荷载的作用,产生的径向荷载在横向截面上引起了较大的拉应力及剪应力,并比较了进行了常规验算。提出了大跨桥梁设计中应注意的问题。     

基于BOTDA技术的预应力钢绞线分布式应力监测技术研究

介绍了一种利用分布式光纤传感技术监测预应力混凝土中预应力钢绞线应力、应变状态的新方法。通过在钢绞线表面布设分布式传感光纤,并安装在预应力混凝土的波纹管内,与同一波纹管中的其他钢绞线同时受拉变形,对预应力钢绞线应变进行分布式测量,从而实现预应力混凝土中预应力钢绞线的分布式应力监测。该技术在某高架桥预应力混凝土横梁中成功应用,揭示了预应力钢绞线应力衰减的变化过程。     

Dynamic effects on buckling and energy absorption of cylindrical shells under axial impact

The crushing behaviour of aluminium and steel cylindrical shells, when subjected to an axial impact, is examined using a numerical simulation. The influence of the material properties, shell geometry, boundary conditions and loading techniques on the energy absorbed and the buckling shapes is explored. Various shell response characteristics, such as the peak load, fold lengths, axial compression and energy absorption are studied. An examination is also made of the influence of filtering on the accuracy of data obtained usually in dynamic tests.     

The effects of long term uniform corrosion on the buckling of ground based steel tanks under seismic loading

Material degradation due to corrosion significantly alters the seismic response of ground-based cylindrical steel storage tanks. A numerical study is conducted to investigate the effects of internal shell corrosion on the dynamic buckling of three cone roof ground-based, steel cylindrical tanks with height to diameter ratios (H/D) of 0.40, 0.63 and 0.95, subjected to horizontal seismic base excitations. Internal corrosion is considered as a time dependent uniform thinning of the wall at the upper and the lower parts of the tank being in contact with, respectively, atmospheric oxygen and acid gases and residual water. Detailed numerical models of the tank–liquid systems at different stages of corrosion degradation are subjected to two representing accelerograms and for each model the critical peak ground acceleration (PGA) for dynamic buckling of the shell and its associated mode of failure are evaluated. It is found that in all three tanks, the critical PGA is markedly reduced with thinning of the shell, irrespective of the type of ground input. The buckling mode of failure of the tanks also changed from an elastic diamond-shaped failure at the top of the shell to an elasto-plastic elephant foot type failure near the base, after 10 years for the shorter tanks (H/D=0.4 and 0.63) and after 15 years for the tallest tank. The effects of uniform corrosion degradation on the critical buckling load of the tanks were found to be such that after 20 years of thinning due to corrosion, the static loading alone was responsible for the elephant foot buckling of the shell.     

Dynamic buckling of anchored steel tanks subjected to horizontal earthquake excitation

We investigate dynamic buckling of aboveground steel tanks with conical roofs and anchored to the foundation, subjected to horizontal components of real earthquake records. The study attempts to estimate the critical horizontal peak ground acceleration (Critical PGA), which induces elastic buckling at the top of the cylindrical shell, for the impulsive hydrodynamic response of the tank-liquid system. Finite elements models of three cone roof tanks with height to diameter ratios (H/D) of 0.40, 0.63 and 0.95 and with a liquid level of 90% of the height of the cylinder were used in this study. The tank models were subjected to accelerograms recorded during the 1986 El Salvador and 1966 Parkfield earthquakes, and dynamic buckling computations (including material and geometric non-linearity) were carried out using the finite element package ABAQUS. For the El Salvador accelerogram, the critical PGA for buckling at the top of the cylindrical shell decreased with the H/D ratio of the tank, while similar critical PGAs regardless of the H/D ratio were obtained for the tanks subjected to the Parkfield accelerogram. The elastic buckling at the top occurred as a critical state for the medium height and tallest models regardless of the accelerogram considered, because plasticity was reached for a PGA larger than the critical PGA. For the shortest model (H/D=0.40), depending on the accelerogram considered, plasticity was reached at the shell before buckling at the top of the shell.     

Shaking Table Test of Steel Cylindrical Liquid Storage Tank Considering the Roof Characteristics

Steel cylindrical tanks are widely used for the storage of hazardous substances of which leakage must be prevented under any circumstances. However, the dynamic response of the steel cylindrical liquid storage tank depends sensitively on the fluid–structure interaction and the vibration of the tank structure and necessitates clarification for the safety of the tank structure. This paper presents the results of shaking table tests performed to examine the dynamic behavior of a scaled cylindrical steel tank model considering the presence or not of fixed roof and added mass at the top of the tank for various fluid levels. The test results confirm the occurrence of both beam-type and oval-type vibration modes and show that the larger content of liquid inside the container amplified the acceleration along the height of the cylindrical tank. The oval-type vibration modes are seen to be more dominant in case of large water-to-structure mass ratio.     

Modelluntersuchungen zur Windeinwirkung auf stählerne Doppelmantelbehälter

The model tests of wind action on the steel double‐shell tanks. The paper shows the results of the wind tunnel tests on the double shell cylindrical vertical tank models with fixed and floating roofs. During tests the pressure distribution onto both shells and onto the roofs was measured. The influence of the following parameters on the wind load value and distribution was analysed: – Distance between tank shells (3 distances) – Type of roof (floating or fixed) – Position of floating roof (4 positions). The measurement results have been presented as graphs of the pressure coefficients (C_p).     

强冰雪灾害下大型薄壁圆柱钢壳结构稳定性研究

2008年我国南方地区发生强冰雪灾害,造成不少钢结构破坏。在化工、电力等工程中有很多作为整个系统关键设备的大型薄壁圆柱钢壳结构,柱壳内通常需设置一些横梁支承工艺设备,壳体既受到由上部壳体、顶盖和设备自重等荷载形成的沿环向均匀分布的整体轴向压力,又受到横梁支座传递来的局部轴向压力。在这些荷载作用下结构已经积累了一定的内力和变形,一旦再遭受强冰雪灾害,面积较大的顶盖和相连的其他管道上会快速积聚较大的雪荷载,导致结构发生失稳破坏。根据结构施工和使用过程,考虑加载路径的影响,先施加整体均布轴向压力,再施加局部轴向压力,然后施加模拟强积雪荷载的均布轴向压力,对112个带焊缝初始缺陷的薄壁圆柱壳结构进行了非线性稳定性数值分析。研究表明:随着初始整体荷载水平提高,柱壳承受积雪荷载的能力下降;随着缺陷幅值的增大,柱壳承受积雪荷载的稳定承载力与整体均布轴压下的稳定设计承载力的比值增大,其后屈曲承载能力也提高。柱壳下部储有浆液时;壳体承受积雪荷载的能力有小幅提高。根据大量计算结果,提出了考虑加载历史的遭受强冰雪荷载的圆柱壳稳定性设计建议。     

Research on seismic behavior and restoring force model of circular steel tubular columns after impacts

为研究冲击荷载作用后圆钢管柱的抗震性能，对12个受冲击荷载作用后的圆钢管柱和3个未受冲击荷载作用的对比柱进行了拟静力试验，研究了冲击高度和轴压比等因素对圆钢管柱破坏模式、滞回性能、延性、刚度退化和耗能能力的影响。基于拟静力试验结果，建立了考虑冲击高度和轴压比参数影响的圆钢管柱恢复力模型。结果表明：冲击高度和轴压比对圆钢管柱的滞回性能均有显著影响，随着冲击高度的增加，滞回曲线由饱满对称的梭形逐渐变为狭窄不对称的梭形，圆钢管柱水平承载力和变形能力逐渐下降，延性和耗能能力显著下降；随着轴压比的增长，滞回曲线的饱满程度显著降低，圆钢管柱承载力和极限位移减小，延性和耗能能力显著降低；受冲击荷载作用后的圆钢管柱恢复力模型计算结果与试验数据吻合良好，可用于工程结构的抗震弹塑性分析。     

冲击荷载作用后圆钢管柱抗震性能与恢复力模型研究

为研究冲击荷载作用后圆钢管柱的抗震性能,对12个受冲击荷载作用后的圆钢管柱和3个未受冲击荷载作用的对比柱进行了拟静力试验,研究了冲击高度和轴压比等因素对圆钢管柱破坏模式、滞回性能、延性、刚度退化和耗能能力的影响。基于拟静力试验结果,建立了考虑冲击高度和轴压比参数影响的圆钢管柱恢复力模型。结果表明：冲击高度和轴压比对圆钢管柱的滞回性能均有显著影响,随着冲击高度的增加,滞回曲线由饱满对称的梭形逐渐变为狭窄不对称的梭形,圆钢管柱水平承载力和变形能力逐渐下降,延性和耗能能力显著下降;随着轴压比的增长,滞回曲线的饱满程度显著降低,圆钢管柱承载力和极限位移减小,延性和耗能能力显著降低;受冲击荷载作用后的圆钢管柱恢复力模型计算结果与试验数据吻合良好,可用于工程结构的抗震弹塑性分析。     

Improvement of mechanical behavior of buried pipelines subjected to strike-slip faulting using textured pipeline

The present study investigates the mechanical behavior of a new generation of buried pipelines, dubbed the textured pipeline, which is subjected to strike-slip faulting. In conventional cylindrical pipelines, the axial and bending stresses brought about in their walls as a result of fault movement, lead to local buckling, which is construed as one of the major reasons contributing to pipeline failure. The present study has assessed 3-D numerical models of two kinds of buried textured pipelines, with 6 and 12 peripheral triangular facets, subjected to a strike-slip faulting normal to the axis of the pipelines, with and without internal pressure, with the two kinds of X65 and X80 steel, and with different diameter-to-thickness ratios. The results indicate that, because of specific geometry of this pipeline shell which is characterized by having lower axial stiffness and higher bending stiffness, compared to conventional cylindrical pipeline, they are considerably resistant to local buckling. The results of this study can be conceived of as a first step toward comprehensive seismic studies on this generation of pipelines which aim at replacing the conventional cylindrical pipelines with textured ones in areas subjected to fault movement.     

CFRP Effect on the Buckling Behavior of Dented Cylindrical Shells

Considering that the use of thin-walled shells is expanding every day, it is important to examine the problem of instability in this form of structure. Many steel structures such as high-water tanks, water and oil reservoirs, marine structures, and pressure vessels, including shell elements, are under stress tension. In addition, shell elements are subject to instability owing to the loads applied. Ten thin-walled cylindrical shell specimens in two groups with different dent depths of t_c and 2t_c, and the different dent number subject to uniform external pressure were tested in the present research (t_c is the thickness of cylindrical shell). The samples were modified to include either one or two dent line with amplitudes of h/3 in height (h the height of cylinder shell). Moreover, CFRP Strips on the dent depth was used in one of the groups. The results of testing under different theories and codes are compared.