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1.
Ten slender steel reinforced cencrete (SRC) composite columns are tested under eccentric loading conditions.Effects of concrete strength, slenderness of columns and eccentricity of the axial load are studied. The load-carrying capacity is reduced with increased slenderness ratio and eccentricity. Concrete strength has no obvious influence on eccentrically loaded columns. Then, a nonlinear numerical method of pin-ended slender columns is also presented. This method is applicable for determining the material failure load or buckling failure load of a slender steel reinforced concrete composite column. In this method both material and geometric nonlinearities are taken into account. The results of numerical analysis accord well with the test results. The test results are also compared with the results predicted by ACI318-05 and the China Specifications. 相似文献
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建立了T形配钢型钢混凝土偏压构件力学性能分析的有限元模型,计算结果得到以往实验结果的验证。在此基础上,分析了不同阶段材料应力状态和各参数对偏压构件力学性能的影响。结果表明:T形配钢型钢混凝土构件在不同加载角下的性能有所不同,加载角为180°时极限承载力大于其他角度情况;混凝土抗压强度、型钢含钢率、配筋率、荷载偏心率、长细比对构件荷载-变形曲线的影响较大,随着混凝土强度、型钢含钢率、配筋率的增加,极限承载力和刚度增加;随着荷载偏心率的增加,极限承载力和刚度下降;随着构件长细比的增加,构件承载力总体呈现线性下降趋势,刚度下降明显。 相似文献
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INTRODUCTION Creep is an internal characteristic of concrete under long-term load. A long time has elapsed since the first discovery of concrete creep in 1907 by Hatt. Many researches have been devoted to this complex problem ever since. However, despite major suc-cesses, the creep phenomenon is still far from being fully understood, even though the phenomenon has occupied some of the best minds in the field, such as Glanville, Dischinger, Troxell, Pickett, Neville, etc. Creep phenome… 相似文献
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The effect of weld reinforcement on axial plastic buckling of welded steel cylindrical shells is investigated through experimental
and numerical buckling analysis using six welded steel cylindrical shell specimens. The relationship between the amplitude
of weld reinforcement and the axial plastic buckling critical load is explored. The effect of the material yield strength
and the number of circumferential welds on the axial plastic buckling is studied. Results show that circumferential weld reinforcement
represents a severe imperfect form of axially compressed welded steel cylindrical shells and the axial plastic buckling critical
load decreases with the increment of the mean amplitude of circumferential weld reinforcement. The material yield strength
and the number of circumferential welds are found to have no significant effect on buckling waveforms; however, the axial
plastic buckling critical load can be decreased to some extent with the increase of the number of circumferential welds. 相似文献
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The creep-induced deformation of the arch rib of concrete-filled steel tubular （CFST） arches under a sustained load can increase the bending moment, which may lead to earlier stability failure called creep buckling. To investigate the influences of concrete creep on the buckling strength of arches, a theoretical analysis for the creep buckling of CFST circular arches under distributed radial load is performed. The simplified Arutyunyan-Maslov （AM） creep law is used to model the creep behavior of concrete core, and the creep integral operator is introduced. The analytical solutions of the time-dependent buckling strength under the sustained load are achieved and compared with the existing formula based on the age-adjusted effective modulus method （AEMM）. Then the solutions are used to determine the influences of the steel ratio and the first loading age on the creep buckling of CFST arches. The results show that the analytical solutions are of good accuracy and applicability. For CFST arches, the steel ratio and the first loading age have significant influences on creep buckling. An approximate log-linear relationship between the decreased degrees of the creep buckling strength and the first loading age is found. For the commonly used parameters, the maximum loss of the buckling strength induced bv concrete creen is close to 40% 相似文献
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This study investigated characteristics of bifurcation and critical buckling load by shape imperfection of space truss,which were sensitive to initial conditions.The critical point and buckling load were computed by the analysis of the eigenvalues and determinants of the tangential stiffness matrix.The two-free-nodes example and star dome were selected for the case study in order to examine the nodal buckling and global buckling by the sensitivity to the eigen buckling mode and the analyses of the influence,and characteristics of the parameters as defined by the load ratio of the center node and surrounding node,as well as rise-span ratio were performed.The sensitivity to the imperfection of the initial shape of the two-free-nodes example,which occurs due to snapping at the critical point,resulted in bifurcation before the limit point due to the buckling mode,and the buckling load was reduced by the increase in the amount of imperfection.The two sensitive buckling patterns of the numerical model are established by investigating the displaced position of the free nodes,and the asymmetric eigenmode greatly influenced the behavior of the imperfection shape whether it was at limit point or bifurcation.Furthermore,the sensitive mode of the two-free-nodes example was similar to the in-extensional basis mechanism of a simplified model.The star dome,which was used to examine the influence among several nodes,indicated that the influence of nodal buckling was greater than that of global buckling as the rise-span ratio was higher.Besides,global buckling is occurred with reaching bifurcation point as the value of load ratio was higher,and the buckling load level was about 50%-70% of load level at limit point. 相似文献
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为解决发电厂灰库现场卸灰环境差,人力浪费的难题,提出了一种新的组合式设计方案,将发电厂灰库的手动卸料改为PLC系统卸料,同时与闭路电视视频监控相结合,形成一个协同作业的卸灰监控系统,使得多个库的卸灰能在干净的值班室内统一简便的完成。这种新的设计方法在景德镇2x660MW超超临界机组新建工程中得到成功应用,使得在灰库值班室内能自由监控三个灰库的卸灰,这种新的设计方案对今后的发电厂灰库值班系统的设计具有指导意义。 相似文献
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:焊接箱形梁腹板存在较高的屈曲后强度 ,可供利用 .对箱形梁腹板在各种受力条件下的屈曲后性能进行了理论分析 ,同时在参考国内外钢结构设计规范的基础上 ,提出了相应的简化分析方法 ,供工程设计和修订规范时参考 .计算结果表明 ,本文提出的分析方法简单可行 相似文献
10.
A numerical investigation of thin-walled complex section steel columns with intermediate stiffeners was performed using finite
element analysis. An accurate and reliable finite element model was developed and verified against test results. Verification
indicates that the model could predict the ultimate strengths and failure modes of the tested columns with reasonable accuracy.
Therefore, the developed model was used for the parametric study. In addition, the effect of geometric imperfection on column
ultimate strength and the effect of boundary conditions on the elastic distortional buckling of complex section columns were
investigated. An equation for the elastic distortional buckling load of fixed-ended columns having different column lengths
was proposed. The elastic distortional buckling load obtained from the proposed equation was used in the direct strength method
to calculate the column ultimate strength. Generally, it is shown that the proposed design equation conservatively predicted
the ultimate strengths of complex section columns with different column lengths. 相似文献
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为准确计算正三角形广告牌面板上的风荷载,对比了《户外广告设施钢结构技术规程》（CECS148：2003）和《建筑结构荷载规范》（GB50009-2012）中关于三面广告牌面板风载体型系数的取值和计算方法,并与正三角形三面广告牌的仿真分析结果进行比较,发现在不同的风向角下《户外广告设施钢结构技术规程》（CECS148：2003）规定的风载体型系数最小,而仿真分析得到的风荷载压力系数最大。为保证结构的安全,基于仿真分析的结果,给出了三面广告牌风载体型系数建议值;同时考虑到风荷载的非平稳性和随机性,引入风荷载的偏心距系数,为落地式三面广告牌的设计提供参考。 相似文献
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在冲击荷载作用下,钢框架结构的动态响应是一个复杂的非线性过程。运用ANSYS/LS-DYNA建立了钢框架的三维模型,对冲击荷载作用下钢框架的动态响应和破坏形态进行研究。采取多点积分算法,有效避免沙漏问题,保证计算结果精确。以冲击块与钢框架的碰撞冲击为例,研究了冲击速度、冲击块质量、冲击位置等参数对钢框架在横向冲击作用下动力响应的影响,并分析冲击荷载下钢框架的破坏形态。结果表明:冲击块的质量、速度、冲击位置的增加都会不同程度地加剧钢框架的动态响应;在冲击作用下,高应变主要出现在被冲击柱子的冲击区域、柱脚处和梁柱节点处;冲击荷载下钢框架的破坏形态为整个框架发生侧移,受冲击柱在冲击处翼缘出现局部屈曲,受冲击区域的截面发生弯扭,未受冲击柱出现倾斜。 相似文献
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讨论弹性有限长度杆端部受冲击载荷作用，在轴向应为波传播和反射过程中的动态屈曲问题．利用扰动方程的解、端部支承条件和应力波反射前后波阵面相容条件得到了动态屈曲的分叉条件，临界载荷和屈曲模态．数值结果表明：临界载荷有多个分支且随时间增加而降低；由于应力波在端部的反射，使临界载荷进一步下降．这个结果就解释了实验中的一些现象． 相似文献
15.
Corrosion is one of the main causes of deterioration in steel structures. Loss of thickness in flanges and web of corroded steel beams leads to reduction in section properties which can reduce the lateral torsional buckling capacity of the member. In this paper, thickness loss data were compiled from four samples of corrosion damaged I-beams removed from a petro-chemical plant. Visual examination of the four corroded beams showed that they were corroded uniformly. To improve the accuracy of the results, a large number of measurements for surface roughness were taken for each beam, totally 770 values to obtain the average thickness of flanges and web of each beam. The data was used to develop a corrosion decay model in order to calculate the percentage remaining lateral torsional buckling capacity of long and short span beams which are laterally unrestrained. To estimate the percentage of remaining lateral torsional buckling capacity in the corroded damaged I-beams, the readily available minimum curves for different types of universal beams in conj unction with information on the thickness loss were used. The results can be used by practicing engineers for better estimation on the service life of deteriorated steel structures. 相似文献
16.
朱怀亮 《上海大学学报(英文版)》2002,6(1):40-44
In this paper,the intrinsic behavior of rotating Euler-Benoulli flexible shafts was studied due to coupled bending and torsional vibratuions,the equations of motion of the shaft with unbalanced eccentricity and visous material damping were derived by the Hamilton principle.The numerical solution was obtained using the perturbation approach and mode-assuming method.The influences of the coupled vibrations between the benging and torsion.the rotaing speed,material damping and the slenderness ratio of the shaft were analyzed.It is clearly shown that the beating phenomena can occur when the interaction of torsion and flexure is considered. 相似文献
17.
Steel plates are widely used in various structures, such as the deck and bodies of ships and bridges, and in the aerospace industry. In many instances, these plates are subjected to axial compression loads that predispose the sheets to instability and buckling. In this study, we investigate the buckling and post-buckling behaviors of steel plates having groove-shaped cutouts of various dimensions and angles using finite element method (FEM) (by ABAQUS software) and experimental tests (by an Instron servohydraulic machine). Boundary conditions were clamped by supports at upper and lower ends and free supports at the other edges. The results of both numerical and experimental analyses are compared, which show a very good agreement between them. Finally, based on the experimental findings, formulas are presented for the determination of the buckling load of such plates. 相似文献
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目的：探讨Tei指数原发性高血压患者心脏功能的临床应用价值。方法：原发性高血压患者176例．按Ganau分类法将原发性高血压分为4型；正常构型（A组，46例）、向心性重构（B组，53例）、向心性肥厚（C组，40例）、离心性肥厚（D组，37例）；正常对照组35例。以常规超声心动图检查测量舒张末期室间隔、左室后壁厚度及左室内径（IVS、LVPW、LVDed），二尖瓣血流频谱图舒张早期与舒张晚期血流峰值比（E／A），左室射血分数（EF）及Tei指数，进行对比分析。结果：1.一般资料的比较：各组同年龄、性别差异均无显著性意义，C、D组病程有显著性差异，C、D组收缩压最高（P〈0．05），B、C、D组脉压最高（P〈0．05）；2．各组超声心动图结构参数比较：C组、D组LA最大（P〈0．05）；B组LVDS最小（P〈0．05），D组LVDS最大（P〈0．05）；C组IVS、LVPW最厚（P〈0．05）；B组、D组IVS、LVPW轻度增厚（P〈0．05）；C组RWT明显厚于其它各组（P〈0．01）；C组、D组LVMI质量显著增加（P〈0.01），但C组、D组之间无统计学意义；3．各组超声心动图功能参数比较：高血压各组的E／A值均减低（P〈0．05），EF只有D组与对照组比较有显著性意义；高血压各组Tei指数均较对照组增加，呈递增趋势，各组间有显著性意义。结论：Tei指数可以客观、真实的评价高血压患者不同左室构型的心功能情况，对于评估疾病的治疗效果和预后具有很高的临床应用价值。 相似文献
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To study the influence of slenderness on the axial compressive performance of autoclaved fly ash solid brick masonry columns, compression experiments were conducted on 12 samples of autoclaved fly ash solid brick masonry column and 4 samples of fired clay brick masonry column. The damage patterns and compressive performance were compared and analyzed. The experimental results indicate that the compressive bearing capacity decreases as slenderness increases from 3 to 18, and the compressive bearing capacity of the autoclaved fly ash solid brick masonry columns is lower than that of the fired clay brick masonry columns. The formulae for the axial compressive bearing capacity of autoclaved fly ash solid brick masonry columns were derived based on the experiments. The nonlinear FEA program ANSYS was adopted to simulate the behaviors of masonry columns. By comparing the simulation results and experimental results, it is shown that the simulation results agree well with the experimental ones. The rationality and applicability of the simulation results were verified. 相似文献
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The National Swimming Center built for the 2008Beijing Olympic Games applies the polyhedron spatialframe structure, which is based on the foam physicstheory[1]. Its simple geometry is a square box of 170m×170 m×29 m. It can hold 17 000 people, theroof o… 相似文献