Q690高强钢端板连接梁柱节点抗震性能试验研究

对3个齐平式端板螺栓连接节点试件进行低周反复荷载试验,其中1个为普通钢端板节点试件,另2个为Q690高强钢端板节点试件。通过改变端板和柱的尺寸与材料,得到普通钢与高强钢端板节点、刚性柱和非刚性柱节点的性能差别,并与欧洲规范EC3的计算结果进行对比。结果表明：Q690高强钢端板节点的受弯承载能力比Q345钢端板节点高30%,但因其端板弹性变形能力较强,易于导致螺栓破坏,因此,需提高螺栓的承载力以提高其延性;刚性柱节点的受弯承载能力与非刚性柱节点基本相同,但其转动能力、延性、耗能能力等抗震性能明显优于非刚性柱节点;EC3组件法普通钢节点承载能力的预测公式可直接用于高强钢端板节点,但转动刚度及破坏模式的预测方法并不适用于高强钢端板节点。     

高强度结构钢研究现状及其在抗震设防区应用问题

近年来,随着钢材生产工艺的进步及一大批重点工程、标志性建筑的兴建,高强度结构钢在工程中的应用逐渐增长。高强度结构钢与普通强度钢材的力学性能存在明显差异,然而现有设计规范的制定是基于普通强度钢结构的试验与理论研究,其能否适用于高强度钢的结构设计有待进一步研究。首先介绍了高强度结构钢的经济性与其在国内外工程中应用的概况,然后总结了国内外关于高强度结构钢在材料性能、基本构件力学行为、连接与节点性能和抗震设计方面的研究成果与现状。已有的研究结果表明,随着钢材强度的提高,其伸长率下降,屈强比升高,延性变差,阻碍了高强度结构钢在抗震结构中的应用。最后对高强度结构钢在地震设防区应用所面临的问题进行讨论,提出了高强度结构钢在抗震结构中应用的两种思路,并指出未来高强结构钢应用仍需开展的研究工作。     

Ductility,strength and stability of concrete-filled fabricated steel box columns for tall buildings

This paper is concerned with the ductility, strength and stability behaviour of concrete filled steel box columns. A cross-sectional analysis procedure which considers the nonlinear material properties of steel and concrete has been developed. The steel behaviour includes the presence of residual strains and stresses. A parametric study is undertaken to monitor the influence of residual stresses, concrete strength and steel strength on the thrust–moment–curvature response. A parameter known as the ductility ratio is calculated and this gives an indication of the ability of a structural member to deform. From the results of the thrust–moment–curvature response, strength interaction diagrams are also developed. Slender column behaviour for these structural members is described and methods by which to determine the strength are discussed. A design example is presented which shows the use of both the strength interaction diagrams and the slender column buckling procedure developed by other researchers. Further research areas are then outlined and discussed in order to elucidate the behaviour and design of these highly efficient column members in tall buildings. © 1998 John Wiley & Sons, Ltd.     

地震下可恢复框架结构冷弯型钢构件试验研究

对地震时作为多层建筑抗弯钢架能量耗散构件的薄壁冷弯型钢(CFS)进行了试验研究。试验采用6个螺栓连接的梁-柱节点,在连接区域的板件和梁的翼缘上使用不同的出平面加劲肋。CFS连接件的滞后性能表明其具有较高的耗能能力和足够的延性,满足抗震设计规范的要求。在连接区域的钢梁内使用出平面加劲肋,能够提高连接件的弯矩-转角特性,强度提高35%,延性提高75%。弹性周期后连接件的滑动使其具有较好的滞回性能,能量耗散能力提高了240%。连接件试样可以作为刚性连接,其全部或部分强度取决于连接加劲肋。     

General notes on ductility in timber structures

The paper discusses the implications of ductility in design of timber structures under static and dynamic loading including earthquakes. Timber is a material inherently brittle in bending and in tension, unless reinforced adequately. However connections between timber members can exhibit significant ductility, if designed and detailed properly to avoid splitting. Hence it is possible to construct statically indeterminate systems made of brittle timber members connected with ductile connections that behave in a ductile fashion. The brittle members, however, must be designed for the overstrength related to the strength of the ductile connections to ensure the ductile failure mechanism will take place before the failure of the brittle members. The overstrength ratio, defined as the ratio between the 95th percentile of the connection strength distribution and the analytical prediction of the characteristic connection strength, was calculated for multiple doweled connections loaded parallel to the grain based on the results of an extensive experimental programme carried out on timber splice connections with 10.65 and 11.75 mm diameter steel dowels grade 4.6. In this particular case the overstrength ratio was found to range from 1.2 to 2.1, and a value of 1.6 is recommended for ductile design. The paper illustrates the use of the elastic-perfectly plastic analysis with ductility control for a simple statically indeterminate structure and compares this approach to the fully non-linear analysis and with the more traditional linear elastic analysis. It is highlighted that plastic design should not be used for timber bridges since fatigue may lead to significant damage accumulation in the connections if plastic deformations have developed. The paper also shows that the current relative definitions of ductility, as a ratio between an ultimate deformation/displacement and the corresponding yield quantity, should be replaced by absolute definitions of ductility, for example the ultimate deformation/displacement, as the latter ones better represent the ductile structural behavior.     

Experimental investigation of extended end plate joints to concrete-filled steel tubular columns

An experimental programme to obtain the behaviour of blind bolted extended end plate joints to circular or square concrete-filled steel tubular (CFST) columns under monotonic loading has been conducted. In order to enhance the strength and stiffness of the connections, the anchorage extensions are provided to the blind bolts to link the connection back into the concrete with the tubular. This paper investigated the effect of the end plate thickness and the column section type on the static behaviour and failure modes of the tested connections. The structural performance of the blind bolted extended end plate connections was evaluated in terms of the moment–rotation relationship, connection rigidity, the deformation pattern and the strain response. The test results showed that the blind bolted extended end plate connection to CFST columns exhibits high strength and stiffness, while its connection rotation capacity satisfies the ductility requirement for earthquake resistance in aseismic region. The experimental studies also demonstrated that the strength and stiffness of the connections can be improved by providing anchorage extensions to the blind bolts, and utilising moderately thick end plates leads to joints approaching full strength for the extended end plate connections.     

梁柱盖板连接的滞回性能研究

盖板加强式梁柱刚性连接节点是使塑性铰外移以提高节点塑性变形的一种改进形式。为了研究梁柱盖板连接的滞回性能,在考虑材料、几何和接触状态非线性基础上,采用三维实体单元对梁柱盖板连接进行了循环加载有限元模拟。设计了4组共12个试件,研究了节点域厚度、梁高、盖板长度及轴压比等参数对盖板连接滞回性能的影响。有限元分析结果表明:大部分节点表现出良好的延性,梁端位移超过80mm;节点域厚度越厚,连接的承载力和刚度越高;梁高越大,连接的延性越差,可能会发生强梁弱柱破坏;盖板长度对节点性能没有显著影响;轴压比越大,节点的强度、刚度和延性会显著降低。     

Seismic behavior of connections composed of CFSSTCs and steel-concrete composite beams—experimental study

In order to investigate the seismic behavior of connections composed of concrete-filled square steel tubular columns and steel-concrete composite beams, fourteen cruciform connection specimens were tested. The strength, deformation, and energy dissipation capacity of these composite connections were analyzed. The test results showed that the strength of connections with interior diaphragms is adequate, but their ductility is low. Also, the deformation capacity of connections with anchored studs is good, but their strength is low. In comparison, the connections with exterior diaphragms have adequate strength, good ductility, and high-energy dissipation capacity, and as a result, it can be concluded that they are more suitable for applications in moment resisting frames in seismic regions.     

Finite element modelling of steel fin plate connections in fire

Recent structural collapses caused by fire have focused attention on research concerning fire safety in building design. Steel connections are an important component of any structural steel building, as they provide links between the principal structural members. The evaluation of the performance of steel connections at elevated temperatures has been a topic of several research programmes in the last few years. Determining the behaviour, available strength and stiffness of moment connections in fire conditions has been a dominant theme in these research works; however very little information on the behaviour of simple shear connections in fire conditions has been disseminated. Fin plate shear connections are easy to fabricate and install; as a result, they have gained popularity with fabricators because of their economy. In this research, the robustness of simple fin plate beam-to-column connections is being investigated under catenary tension from highly deflected beams in fire. A highly detailed three-dimensional (3-D) finite element (FE) model has been created using the ABAQUS software. This is a complex model accounting for material and geometric non-linearity, large deformation and contact behaviour. Contact is critical to model the shear behaviour of the joint, and contact elements have been used both at the bolt–hole interface and also at the surface between the web of the beam and the fin plate, taking into consideration friction between the surfaces. The connection model has been analysed through the elastic and plastic ranges up to failure. Bolt shear and bending, and plate and web bearing have been observed as failure modes. A comparison between available experimental data at ambient and elevated temperatures and other analytical results shows that the model has a high level of accuracy. When the connection model was extended to include an attached beam, it was found that it eventually experiences large tensile force when exposed to fire.     

Investigation of ductility in hybrid and high strength steel beams

Compactness and lateral support configuration provisions for design of steel beams are formulated so as to ensure that the resulting beam exhibits adequate ductility. It appears from the current research that slenderness limitations are not valid for beams made of the high strength steel grades. In this paper an attempt is made to study on influence of flange and web slenderness as well as lateral support spacing of homogenous and hybrid welded I-sections made of high strength steel on member ductility. For this purpose an experimentally verified nonlinear numerical analysis of the local and overall stability was performed. These beams are subjected to constant moment loading a new theoretical method is proposed to calculate the rotation capacity for this loading type. A comparative study was carried out between this method and numerical study results to ensure the accuracy of proposed method. In this research realistic material behavior and residual stresses were adopted in finite element models. Results have shown that using the high strength steel in cross sections subjected to bending has a significant effect on flexural behavior of these members. Meanwhile, in present study, interaction between the flange and web slenderness ratios was evaluated in accordance to AISC criteria for compact sections.     

Strength and ductility of HPS flexural members

An experimental and analytical research program was recently completed that examined in detail the parameters affecting the strength and ductility of high-performance steel (HPS) flexural members. HPS is a term used to describe a new class of steels being produced under strictly controlled conditions that have high strength, usually greater than 448 MPa (65 ksi) and exceptional toughness and weldability. The mechanical characteristics of these steels are different from conventional steels, leading to concerns over their use in some structural applications. Under earthquake loading, flexural members are expected to deform inelastically, so members fabricated with HPS steels must possess adequate ductility. This paper discusses the inelastic behavior of welded, I-shaped flexural members fabricated from an HPS steel, HSLA-80, having a nominal yield stress of 550 MPa (80 ksi) and an ultimate strength between 610–690 MPa (90–100 ksi) and compares the results to similar flexural members fabricated from conventional A36 steel. The effects of material properties: yield stress, strain-hardening modulus, yield stress-to-ultimate strength ratio, and strain at ultimate stress; cross-section geometry: flange slenderness, web slenderness, and lateral slenderness; and loading condition: monotonic moment gradient, monotonic uniform moment, and cyclic moment gradient are described from the results of experimental testing and analytical modeling. The results are evaluated against the existing design criteria established in the AISC-LRFD specifications and recommendations are made for revising the specifications.     

高强钢与普通钢混合连接抛丸表面抗滑移系数试验研究

高强度结构钢延性较普通钢差,不宜应用于抗震设计中会出现塑性铰的高延性需求构件。在抗震设防区建筑结构中,高强钢构件宜与普通钢混合使用以满足结构抗震要求。因此,需对高强钢与普通钢混合连接的摩擦面抗滑移性能进行研究。文中以国产Q550、Q690、Q890三种等级高强钢搭配Q235与Q345普通钢制作了30个试件进行混合连接抛丸表面的抗滑移系数测量试验,并将试验结果与同等级高强钢连接抛丸表面抗滑移系数试验结果进行对比。结果表明,混合连接抛丸表面抗滑移系数大于同等级高强钢连接表面抗滑移系数。设计中,建议其取值与同等级高强钢连接表面抗滑移系数保持一致：Q550钢的混合连接抗滑移系数取0.50,Q690与Q890钢混合连接系数可取0.45。为分析抗滑移系数的影响因素,文中测量了同批次试件的钢材硬度、粗糙度、变形能力。分析结果表明,抗滑移系数受到接触表面的粗糙度及摩擦面相对变形能力的影响,而摩擦面相对变形能力受到材料本身塑性及不同材料塑性变形能力匹配度的共同影响;随着钢材等级的增加,抛丸表面粗糙度及钢材变形能力的下降,导致更高等级高强钢混合连接抗滑移系数的降低。     

高强度钢材钢结构的工程应用及研究进展

为研究高强度钢材钢结构的受力性能,了解国内外最新研究进展,促进该类新型绿色节能结构体系的更广泛应用,并为今后的相关研究提供参考和指导,对国内外高强度钢材钢结构的工程应用和最新的研究进展进行总结,特别是清华大学近期所做的一系列试验研究,包括高强度钢材的静力力学性能、韧性和循环荷载下的本构模型,构件截面的残余应力分布、受压钢柱的稳定性能和滞回性能、高强度钢材板件螺栓连接的延性和承载力,高强度钢材钢框架的抗震性能以及高强度钢材钢结构的相关有限元分析等内容。结果表明,高强度钢材钢结构在材料、构件和结构体系三个层面上都具有明显的优势,但现有的设计方法并不完全适用,需要发展新的设计理论和计算公式,以期更合理、安全地应用高强度钢材钢结构。     

螺栓连接的冷成型钢结构的结构性能

本文介绍了一系列螺栓连接的冷成型钢结构的结构性能的试验和理论研究。首先,研究了搭接剪切试验中冷成型钢条之间螺栓连接的基本变形特性,并采用了包含实体单元和接触单元的高等有限元建模作为对比。其次,介绍了带有螺栓抗弯连接的搭接Z型截面的结构性能,对搭接Z型截面的强度和刚度做了解析方法和数值方法的评估。最后,采用数值方法对双跨搭接Z型檩条的结构性能进行了研究,考察了跨越内部支座的搭接Z型截面对于沿檩条构件内力分布的影响。本文意在提供分析和设计方法,以便于结构工程师理解,使他们能够设计和建造出结构性能更好的冷成型钢结构房屋。     

Instability of beams with reduced beam section moment connections emphasizing the effect of column panel zone ductility

Column panel zone (PZ) ductility significantly affects the failure mode of beams with reduced beam section (RBS) moment connections. Even though good hysteretic behaviour is expected in connections with strong PZs, their flexural strength considerably deteriorates due to beam instability. In contrast, weak PZs are prone to high shear deformation, resulting in brittle fracture of connections. This study aims to question the provisions specified in the codes for the design of PZs. To this end, a numerical analysis was conducted on a series of subassemblies with various PZ properties. Use of lower deep sections is another major concern. It is indicated in this study that partial shear yielding in PZs can improve the hysteretic response of specimens by avoiding premature instability in beams. The results show that the PZ ultimate shear strength commonly prescribed in the design codes does not extend to an adequate safety margin. Furthermore, a new parameter is expressed for controlling an RBS beam as regards instability. This parameter is able to appropriately model the behaviour of RBS beams. The results are generally in good agreement with the existing experimental data.     

Strength and ductility of corner materials in cold-formed stainless steel sections

The cold work from the manufacturing process of cold-formed steel members can enhance the strength but reduce the ductility of materials. Due to a high cost of stainless steels, it is desirable to utilize this enhanced strength and avoid the early fracture in cold-formed stainless steel members. The paper is concerned with the prediction of the enhanced stress–strain behaviour and reduced ductility of corner materials in cold-formed stainless steel sections. The enhanced strength of corner materials has been traditionally determined using empirical models. However, most of these empirical models are only able to predict the enhanced 0.2% proof strength, but are neither capable of predicting the enhanced ultimate strength nor able to determine the reduced ductility. This paper first presents a modified weighted-average method for predicting the post-ultimate stress–strain behaviour and the fracture strain for stainless steels. An advanced numerical approach is next presented for predicting the full-range stress–strain behaviour of corner materials in cold-formed stainless steel sections, in which the modified weighted-average method is incorporated. The accuracy of this approach is demonstrated by comparing its predictions with test results. The proposed approach is generally applicable to cold-worked materials for predicting their enhanced strength, reduced ductility and full-range stress–strain behaviour. The proposed method and numerical results can explain why and how the ultimate strength of cold-formed steels can be increased and how the post-ultimate stress–strain behaviour can be utilized through cold working.     

高强度钢端板连接的试验性能分析

高强度钢在结构中的应用给结构工程师提出了不少挑战。其中一个挑战就是,当材料可以提供更高强度时,可以将横截面尺寸最小化,这将带来巨大的经济效益。然而,与低碳钢相比,高强度钢材存在高屈服率和受限的变形能力等缺点。在可导致弹塑性变形的不规则荷载作用条件下进行结构设计时,这个性能至关重要。在这种情况下,构件和连接件都需要具备足够的延性,尤其是构件之间的连接件,需要能提供更高的变形能力。为此,对端板采用高强钢S690的弯矩连接进行试验分析。主要分析内容有:(i)非线性性能特征;(ii)对比现行欧洲规范3标准;(iii)高强钢弯矩连接的延性分析。试验结果表明,试验中的连接件可以给结构提供足够的刚度和抵抗能力,并具有理想的转动能力。     

Comprehending the ductile behavior of slotted bolted connections

Structural steel special moment frames are designed to resist earthquakes with substantial inelastic energy dissipation. The ductile beam‐to‐column connections become more popular over these years by dissipating the earthquake input energy at beam ends. The paper provides a comprehensive study of a high‐strength slotted bolted connection (SBC). Slotted holes instead of round holes are used for the connection such that frictional sliding could be developed. Experimentally, a standard bolt–weld connection as well as three similar slotted bolted connections were designed and tested. The load‐carrying capacities, the ductile deformations, the energy dissipation capacities, and the hysteretic characteristics of the specimens were presented. The overall performance of the steel connections by replacing the circular holes with slotted holes is evaluated, and the design recommendations of the flange gusset plate with slotted holes are provided. Numerically, the nonlinear SBC behavior was simulated and calibrated against the experimental results. The SBC effectiveness as well as the parametrical influences have been presented in details. Results show that the friction slippage behaviors of the specimens with slotted holes provide better ductility, higher plastic deformation capacity, and increased load‐resisting capacities near the ultimate strength.     

A study to enhance the deformation capacity of beam-to-column connections using high strength steel having high yield ratio

As structures are becoming bigger and more having long span, construction materials are also becoming higher performance materials. In response to this trend, 800MPa tensile strength class structural steel was developed in South Korea. Currently, many experiments applied high strength steel about flexural members, compression members, and connections are continuously conducted, but the design guideline for high strength steel has yet to be established. From among these, it is more difficult that planning of ductile beam-to-column connections because of the high yield ratio, which is the characteristic of high strength steel and related studies are not sufficient. Therefore, This study proposed connection details for the purpose of enhancing the deformation capacity of high strength steel beam-to-column connections and it conducted full-scale experiment and FEM analysis using the connection detail as the variable. As the connection detail, it applied non-scallop welding method and improved horizontal stiffener construction method. Especially, it suggests the stress balance design formula for the improved horizontal stiffener construction method, in order to improve the efficacy of strain distribution. Through the results of experiment and FEM analysis, it was analyzed structural performance of connections with proposed details, and it suggested the design scope of the improved horizontal stiffener.     

预应力型钢混凝土梁-钢管混凝土柱节点抗震性能试验研究

通过5个试件的低周反复荷载试验,对预应力型钢混凝土(PSRC)梁-钢管混凝土(CFT)柱节点的受力过程、破坏形态、滞回曲线、骨架曲线、强度与变形特征值、延性、变形恢复能力、刚度退化、耗能能力等抗震性能进行了较为系统的研究,对预应力、轴压比、预应力筋穿越钢管壁的成孔方法（先成孔与后成孔）等因素对节点抗震性能的影响进行了分析。研究结果表明：PSRC梁-CFT柱节点发生了节点核心区剪切破坏;节点核心区水平剪力-剪切变形滞回曲线较丰满,但在大变形阶段有一定的捏拢效应;各试件节点核心区的极限剪切变形介于28.60×10^-3~60.90×10^-3 rad,剪切变形延性系数则介于4.72~6.69;各试件节点核心区的剪切刚度退化规律基本一致;施加预应力及后成孔方法对节点核心区受剪承载力有一定的有利影响,但施加预应力对节点核心区剪切变形能力及剪切变形延性不利;当轴压比n从0.2增至0.4时,节点核心区受剪承载力提高16.62%,而轴压比n从0.4增至0.6时,节点核心区受剪承载力仅提高1.09%。