铜筒仓转折环染的稳定设计准则

钢筒仓结构广泛应用于矿业、冶金、化工、电力、农业等诸多领域中的散料储存。圆形铜筒仓通常由仓筒、锥形漏斗及支承裙筒组成。在仓筒与漏斗的连接处通常设有一道环梁，以承受由漏斗壁上拉力的水平分力所产生的周向压力。常见的环梁形式包括环板形环梁、Ｔ形环梁以及角钢形环染。环梁在周向压力作用下的破坏模式包括塑性破坏、弹性屈曲以及塑性屈曲。近年来对于均匀支承环梁的屈曲及破坏强度已有了系统的研究，本将总结这些研究成     

弦支结构体系概念与分类

"弦支结构"明确定义了结构的各组成部分和特点:"弦"指结构下部犹如弓弦的拉索;"支"指结构中部起到支撑作用的压杆;"结构"是指弦支结构上部的具体结构形式。在介绍结构概念的基础上,将弦支结构分为平面型弦支结构、可分解的空间型弦支结构和不可分解的空间型弦支结构;提出弦支网架、弦支混凝土楼盖、弦支筒壳和弦支拱壳结构;结合相关研究成果,给出3种命名分类方案;建议将此类结构体系统一称为弦支结构体系,并按照结构概念明确和体系系统完整的原则对此类结构形式进行分类。     

压型钢板-混凝土组合楼板的承载能力研究

压型钢板-混凝土组合楼板的承载能力受楼板叠合面的纵向抗剪能力控制。本文通过3组组合楼板的荷载试验,研究了单跨简支组合楼板和两跨连续组合楼板的极限抗剪和抗弯性能。试验结果表明:组合楼板的极限承载能力受叠合面的纵向抗剪能力控制;与简支组合楼板相比,连续组合楼板承载能力有明显提高,跨中挠度显著减小,端部支座剪力出现滑移时与简支板端部剪力值相近,显示了连续组合板的端部滑移与剪力的关系与简支板的情况相似。但与简支组合板不同的是,连续组合板端部出现滑移后,其极限承载能力明显高于相同跨度简支板极限承载力。根据试验结果,得到了组合楼板叠合面纵向抗剪能力的计算公式。在组合楼板的承载力设计中,应对支座端部的竖向剪力进行叠合面的纵向抗剪能力验算,文中提出了连续组合楼板的承载力计算方法。     

底层大开间框剪组合墙房屋:Ⅰ抗震性能研究

分析了底层大开间框剪、上部小开间组合墙房屋的受力特点,采用串并联多质点弹塑性 动力计算程序,分析了房屋的抗震性能及座落在纵向托梁上的横墙的动力响应,得出的结论是这 类房屋的抗震性能与底层框剪组合墙房屋相似,可作为底层框剪组合墙房屋来处理。     

Steel cantilever strength by inelastic lateral buckling

Methods used for the design of steel beams supported at both ends are not well suited for the design of cantilevers against lateral buckling. The end restraints are very different for cantilevers, and the maximum displacements and twist rotations take place at the free ends, instead of near mid-span. Consequently, their buckling modes are very different to those of supported beams. The methods of allowing for the effects of the moment distribution on the elastic and inelastic buckling of supported beams use a mean of the moment distribution, which is weighted to allow for the maximum deformations being near mid-span. These methods are clearly inappropriate for cantilevers whose deformations are greatest at the free ends.Lateral buckling design methods for cantilevers are modifications of the methods for supported beams, but are of doubtful accuracy, and may be over conservative. In some cases there is little or no design guidance.This paper summarizes information on the effects of the moment distribution and load height on the elastic buckling of cantilevers which can be used in the method of design by buckling analysis. It then extends a method of designing supported beams by inelastic buckling analysis to allow for the effects of the moment distribution on the inelastic buckling of cantilevers. This extended method is then used to provide improved design methods for cantilevers which are consistent with those for simply supported beams. A worked example is summarized.     

无伸缩缝桥梁动力特性与抗震性能研究

以福建某简支梁桥为研究背景(该桥在实际工程中已被改造为半刚性整体桥),采用MIDAS/Civil软件将原简支梁桥改造为整体桥、半整体桥与延伸桥面板桥,分别建立了5座桥的全桥有限元模型,分析了它们在地震荷载下的受力差异。结果表明:简支梁桥在地震荷载作用下易引起主梁在桥台处的落梁现象,而无缝桥可有效防止该现象的发生,其中的整体桥表现出更优的抗震性能,更适用于强震区; 在地震荷载作用下,无缝桥与简支梁桥的桩基有效作用长度均在0～10D(D为桩径)埋深范围; 整体桥桩基在大震作用下的受力性能较好,可更好地保护桩基不被破坏; 延伸桥面板桥与传统简支梁桥台底桩身受力相近,其设计可参考现行有缝桥设计规范; 无缝桥与传统简支梁桥的墩底弯矩均最大,在该处易形成塑性铰; 纵桥向地震荷载作用下,简支梁桥与延伸桥面板桥的主梁受力最不利位置分别出现在跨中与墩顶处,而整体桥、半刚性整体桥与半整体桥出现在台顶处,其受力不利部位在设计中应引起重视; 该研究结果可为无缝桥的设计计算与相关规范的制定提供参考。     

Vibration reduction of elastically supported beams under moving loads by tuned mass devices

This study is aimed at the physical interpretation of the function of a tuned mass (TM) in suppressing the vibration response of an elastically supported beam to a moving train. The train is simulated as a sequence of moving loads, and the vibration shape of the elastically supported beam is approximated as the combination of a flexural sine mode and a rigid body mode. By distinguishing free vibration from forced vibration, resonance of the beam is identified as the superposition of the free vibrations induced by the moving loads that are in phase. The reverse is also true for the phenomenon of cancellation. Moreover, the mechanism of the TM in reducing the resonant response of the beam to the moving loads can be interpreted using similar concepts. From the parametric study, it is concluded that the use of a mass ratio of 0.01 is most efficient for the TM. To achieve the greatest effect of mitigation, the frequency of the TM should be tuned to that of the elastically supported beam.     

Vibration reduction of elastically supported beams under moving loads by tuned mass devices

This study is aimed at the physical interpretation of the function of a tuned mass (TM) in suppressing the vibration response of an elastically supported beam to a moving train. The train is simulated as a sequence of moving loads, and the vibration shape of the elastically supported beam is approximated as the combination of a flexural sine mode and a rigid body mode. By distinguishing free vibration from forced vibration, resonance of the beam is identified as the superposition of the free vibrations induced by the moving loads that are in phase. The reverse is also true for the phenomenon of cancellation. Moreover, the mechanism of the TM in reducing the resonant response of the beam to the moving loads can be interpreted using similar concepts. From the parametric study, it is concluded that the use of a mass ratio of 0.01 is most efficient for the TM. To achieve the greatest effect of mitigation, the frequency of the TM should be tuned to that of the elastically supported beam.     

框支剪力墙结构体系的简化抗震分析

本文把框支剪力墙结构体系的首层部分,作为耦联的弯剪弹簧支座,假定楼板在平面内的刚度为无限大,在此基础上提出了框支剪力墙结构体系的静力计算方法。并按耦联弹簧支座上的弯剪杆,提出框支剪力墙自由振动和抗震分析的简化计算方法。     

山地掉层RC框架结构振动台试验研究

为研究具有不等高基础约束的山地掉层框架结构的地震响应特征和破坏机理,及其与等高基础约束的典型框架结构的差异,设计和制作了总层数均为6层的1/8缩尺掉层RC框架结构和典型RC框架结构模型。通过振动台试验,对两者不同地震强度时的试验宏观现象及动力特性、加速度响应、位移响应、层间位移角等进行对比研究。试验分析表明：掉层RC框架结构的振型曲线及顺坡向的变形特征与典型框架结构不同,掉层RC框架顺坡向的整体变形并非剪切型,且有明显的扭转效应;掉层框架结构的破坏形式不同于典型框架结构,典型框架最终表现为部分楼层屈服机制,而掉层框架的柱铰最先出现于上接地柱端,随地震强度的增大,柱端塑性铰向掉层部分转移,掉层接地角柱底部损伤增加显著,结构在罕遇地震及更高强度的地震作用下能保证较好的整体性,但上接地柱破坏较严重。     

弦支结构施工技术研究

弦支结构体系越来越多地应用于重要的公共建筑中,但目前国内外对弦支结构的施工技术方面的系统研究较少。对平面型弦支结构、可分解的空间型弦支结构和不可分解的空间型弦支结构的施工技术分别进行分析和总结,从索的张拉方式、钢结构的安装等施工技术方面进行较为深入的探讨,并指出不同类别结构的施工技术需注意和待研究的问题。     

框支剪力墙、落地剪力墙和壁式框架在水平荷载作用下共同工作时的内力和位移

本文用分区混合法求框支剪力墙、落地剪力墙和壁式框架在水平荷载作用下共同工作时的内力和位移,是文献[1]的继续。对三种常用水平荷载下的内力和位移给出了计算公式。 框支剪力墙和落地剪力墙的共同工作,多肢剪力墙和壁式框架的共同工作均为本文的特殊情况。     

Buckling strength of steel plating with elastically restrained edges

The twin aims of the present study are to investigate the buckling strength characteristics of steel plating elastically restrained at their edges and also to develop simple design formulations for buckling strength as a function of the torsional rigidity of support members that provide the rotational restraints along either one set of edges or all (four) edges. The characteristic equation for the buckling strength of steel plating that is elastically restrained along either long or short edges while the other edges are simply supported was derived by an analytical method. Using the computed results obtained by directly solving the buckling characteristic equation, closed-form expressions of the buckling strength of the plating with one set of edges elastically restrained while the other set of edges is simply supported are derived empirically by curve fitting. Based on the insights developed in the present study, approximate equations for the buckling strength for plating with all edges elastically restrained are proposed as a function of a relevant combination of the three simpler edge condition cases (i.e., long edges elastically restrained/short edges simply supported, long edges simply supported/short edges elastically restrained, and all edges simply supported). The effect of distortion of support members before the plating buckles is also approximately accounted for. The validity of the proposed closed-form buckling strength design formulations is studied by a comparison with theoretical and numerical solutions.     

Behaviour of shotcrete supported rock wedges subjected to blast-induced vibrations

The static state of stress at the brow in a sub-level caving mine is, due to stress re-distribution, almost uniaxial (major principal stress perpendicular to the cross cut). Since large amounts of explosives are detonated in each production round, the impact of stress waves on the brow can be significant. An extensive failure mapping programme in the Kiirunavaara mine showed that many of the failures close to the brow were structurally controlled. Furthermore, the area of damaged shotcrete was extensive when plain shotcrete was used. At brows supported by fibre reinforced shotcrete, damage in the roof was observed within a horizontal distance of about 3 m from the drawpoint. To study the behaviour of roof wedges supported by shotcrete and subjected to blast-induced vibrations a single-degree-of-freedom (SDOF) model was developed. The model consists of a shotcrete layer and a rock wedge.Vibration measurements showed that maximum particle velocity was approximately 1.2 m/s. The acceleration record showing the largest magnitude was used as the load in the dynamic analyses.The analyses showed that a wedge can be ejected by a dynamic load even if the static safety factor was >10. Furthermore, the non-linear response of the wedges was in most of the cases greater when the wedge was supported both by the joints and the shotcrete layer compared to the case when the wedge was only supported by shotcrete. A conclusion from the analyses is that it is difficult to predict the dynamic response from static calculations.To provide a safe working environment close to the drawpoint, the rock support must sustain the impact of stress waves from production blasting. To support rock wedges subjected to dynamic load the support must be able to consume the energy imposed on the wedges from blasting. The non-linear numerical analyses showed that reinforced shotcrete has the necessary bearing capacity to support the wedges formed in the roof of the cross cut close to the brow. This was in fair agreement with the failure mapping.The single-degree-of-freedom (SDOF) model can be used to study the response of an arbitrarily shaped rock wedge supported by shotcrete as long as the movement of the wedge can be idealised by a pure translation and the dimensions of the wedge are small compared to the length of the incident wave. Analyses showed that 2D wedges can be used to judge whether symmetric or non-symmetric 3D wedges in a uniaxial stress field (which occurs close to the brow) are stable or not when they are subjected to waves induced by blasting.     

弦支筒壳结构在多点输入下的地震响应分析

将拉索与柱面网壳相结合,就可以形成新的弦支结构——弦支筒壳结构.以一实际工程为例,本文将分别采用地震波一致输入和考虑行波效应的多点输入分析方法对弦支筒壳进行地震响应分析.结果表明,地震作用下单层筒壳杆件内力和撑杆内力随时间的变化都是在某一数值上下波动,而下弦索内力随时间的变化则是波动着上升.与一致输入相比,多点输入时,单层筒壳杆件内力有些发生了方向改变,有较少一部分内力减小,大部分杆件的内力增大,且随着行波速度的减小,内力增大的杆件增多,幅度加大;一部撑杆的内力增大,也有相当一部分撑杆的内力减小,且随着行波速度的增大,二者对撑杆内力的影响趋于相同;下弦索中拉力或者增大或者趋于与一致输入时相同,且随着行波速度的增大,二者对下弦索中拉力的影响趋于相同.     

Finite‐Elemente‐Methode für geotechnische Nachweise nach neuer Normung?

Geotechnical design according to new standards by using the finite element method. Geotechnical design is done increasingly by incorporating the finite element method (FEM), supported by growing PC‐power. It is discussed and explained by an example to what extent this method can be used as to verifications according to European and German standards. Safety margins given in the standards are based on certain models and the according experience that cannot be transferred to other approaches. It shows that actions and effects determined by FEM are applicable in verifications according to DIN 1054 and EN1997‐1, approach 2*. Also resistances can be calculated using FEM, but there is not enough experience to date to judge the reliability of such approaches. Therefore resistances should be determined the traditional way. Consequently there is no justification for an alteration of the factors of safety as set in the standards at the present time.     

薄板大挠度梁函数解法

在均布荷载和集中荷载作用下,本文用两端固支、两端简支,左端固支右端简支的梁函数,解算薄板卡门大挠度方程,获得简便而实用的方法。计算结果与贾春元所得的结果比较,说明本文的方法是可靠的。计算可采用PC-1500微型机进行。     

Elastic post-buckling analysis of compressed plates using a two-strip model

This paper shows that a simple two-strip model can be used to describe the post-buckling behaviour of simply supported rectangular plates subjected to uni- and biaxial compression, provided the ratio of the post-buckling to pre-buckling stiffness of the perfectly flat plate is known. The formulas for this two-strip model are derived in two ways: by using a force method, and by using an energy method. The two-strip model is compared to other available solutions in literature and it is shown that the model can be regarded as a modification of the lower bound plate analysis method.     

各工程作业考虑下简支组合梁结构性能的数值分析(英文)

提出了一个有关组合梁结构性能的全面数值分析,针对剪切变形效应、不同施工方法、不同程度的钢构件截面应变硬化等情况下,对简支组合梁结构性能进行了一系列的数值分析。使用先进的三维有限元方法,模拟输入特定的材质、几何尺寸、非线性的界面,分析和讨论了24组简支组合梁的承载能力和变形特性。通过分析和考虑两种不同的施工方法,包括混凝土浇筑组合梁时仅采用端部支撑及混凝土浇筑组合梁时采用全支撑,发现剪切连接件滑移的要求在前者的情况下相对较小。另外,若同时考虑欧洲规范第3及第4部分中提及的钢构件截面应变硬化效应后,在全剪切连接情况下,组合梁承载能力有8.5%的显著提升。然而,随着剪切连接程度的减少,截面应变硬化作用减弱,同时,对剪切连接件滑移的要求也会随之减少,因此这样的变化对于组合梁里允许应变而非延性的剪切来说是非常重要的。     

Anchorage and shear strength properties for composite tendons used in earthwork support systems

When employing advanced excavation techniques (e.g. continuous mining methods, mechanized tunnelling, etc.) it may be often necessary to excavate through previously supported areas. This means that the cutting heads of the excavation machine have to come into contact with supporting elements. In such situations, use of conventional steel support systems may damage the cutting bits of the machine, and thus, the support system must have the ability to be cut by standard cutters. As an alternative, composite tendons have the potential to be used as a support system in such conditions. The advantages of this type of bolts are; their cuttability, resistance against corrosion, and increase in rate of installation due to their lighter weight. The aim of this study is to explore the potential for use of composite tendons in situations that automated excavating techniques are to be used in grounds previously supported. As part of a research project with the Amirkabir University of Technology, a literature survey was conducted to explore the possibilities of the use of composite material as a support system in underground infrastructures. Secondly, the results of experimental study conducted by the author on two types of composite tendons are presented. Moreover, experiments were carried out on resin, as grouting material, and a summary of test results are presented. The experimental findings show that Weldgrip tendons have a very good capacity under shear loading. Also Weldgrip outer surface profile provides good pull-out strength as well as high residual load-bearing capacity.