轻质混凝土拼装墙板填充钢框架协同抗震性能试验研究

为了研究墙板与钢框架结构之间的协同抗震性能,对采用不同墙框连接节点的轻质混凝土拼装墙板填充钢框架进行了低周往复荷载试验。通过对比试件的承载力、滞回性能、刚度、耗能以及延性性能,探讨了轻质混凝土拼装墙板及其整体性对结构抗震性能的影响。结果表明:填充墙板钢框架结构的最终破坏形态以墙板挤压开裂,框架梁柱端部翼缘屈曲为主;轻质混凝土拼装墙板与钢框架协同工作,有利于提高结构整体的承载力和变形能力,减轻钢框架在平面内的屈曲破坏;与刚性节点相比,采用柔性节点连接墙板与钢框架对结构的承载力、层间刚度和耗能能力更为有利;增强拼装墙板的整体性,有助于提高结构整体刚度、变形和耗能能力。研究结果可为轻质混凝土拼装墙板填充钢框架结构的抗震设计提供参考。      

钢框架刚性连接的抗震性能分析

通常认为钢框架具有良好的抗震性能,但在最近的几次大地震中许多高层钢结构房屋的梁柱刚性连接节点受到严重破坏.这说明传统的刚性连接框架在某些方面存在不足之处.文章对刚性连接框架的形式以及抗震性能进行了深入的分析和总结,并在设计、构造、及施工三方面对提高刚性连接框架的抗震性能提出一些意见和建议.     

Summary of SAC Case Study Building Analyses

Summarized in this paper are the major findings from analytical studies of nine steel moment frame buildings conducted under Phase 1 of the SAC Steel Project. The buildings range in height from two to seventeen stories and most of them experienced damage to welded beam-column connections during the Northridge earthquake of 1994. Elastic response spectrum, inelastic static pushover, and elastic and inelastic time-history analyses were conducted using ground motion data representative of the Northridge earthquake to establish the loading∕deformation demands that the buildings experienced. The primary performance indices obtained from the analyses were demand-to-capacity ratios, interstory drift ratios, and inelastic hinge rotations. Maximum ratios of elastic member force demands to plastic strengths ranged between 1.0 and 2.0; maximum inelastic hinge rotations were 0.005–0.010 rad; and maximum interstory drift ratios were from 1 to 2%. These damage indices increased by 50%–150% under more severe ground motions recorded during the Northridge earthquake at the Sylmar site. Accuracy of the analyses is shown to be sensitive to a number of modeling parameters including finite joint size, joint panel behavior, composite beam action, strain hardening, second-order (P-Δ) effects, and three-dimensional response. Overall, there was only modest correlation between the frame performance indices and the observed connection damage, due largely to the fact that significant aspects of the connection fracture behavior are not captured in the frame analyses.     

Exact Solution of Nonlinear Hysteretic Responses Using Complex Mode Superposition Method and its Application to Base-Isolated Structures

In this paper, the responses of the structures subjected to arbitrary ground motions are evaluated. With the problem formulated in a state-space form, an exact solution scheme capable of dealing with a variety of material cases is proposed, including cases when postyield stiffness exhibits strain-hardening, strain-softening, and elastic-perfectly plastic properties, respectively. The proposed method can provide much higher accuracy, and requires less computational effort than the traditional step-by-step integration solution technique. The reason for these advantages is discussed and the related formulas are provided. In addition, a new efficient approach is provided for evaluating dynamic response of nonlinear base-isolated structures by taking advantage of their characteristics. Two buildings excited by real earthquake and harmonic ground motions are considered in numerical examples to demonstrate the efficiency of the proposed method.     

高层建筑混合结构设计

文章简要介绍了型钢混凝土混合结构构件的特性、适用范围和其它结构相比较的优缺点,以及目前高层建筑混合结构的设计要求,并从结构布置总体要求、适用高度和高宽比限值、概念设计要点、结构计算分析特点等几个方面进行论述,强调了混凝土筒体延性和钢框架柱地震剪力调整的重要性。     

设防烈度对框架—核心筒结构受力性能和材料用量的影响

为了考察设防烈度对钢筋混凝土框筒结构受力性能、材料用量的影响,在充分调研了目前我国100 m以上已建或在建超高层建筑的基础上,选择150~300 m范围内钢筋混凝土框架-核心筒办公类超高层作为代表性研究对象,建立了12个不同烈度、不同高度下的计算模型,详细分析了其结构的周期比、剪重比、刚重比、地震作用和风荷载影响等结构受力性能以及结构的用钢量、混凝土用量随设防烈度的变化情况.研究结果表明,对于济南恒大国际金融中心工程,随着设防烈度的提高,结构自振周期减小,扭转周期滞后于平动周期,扭转效应减小,而结构剪重比明显增加;低烈度地区结构受重力二阶效应的影响较大,整体稳定性成主要安全控制因素;地震作用的影响随设防烈度的增加而增大;6度区建筑超过200 m后,用钢量明显增加,而8度区用钢量随建筑高度呈线性增长;6度和7度区单位面积混凝土用量接近,而8度区混凝土用量增幅约为19%左右,所以设防烈度对结构工程材料用量影响显著.      

Experimental Evaluation of a Sacrificial Seismic Fuse Device for Masonry Infill Walls

Presented herein are the details and results of an experimental study conducted to evaluate the performance of a proposed infill wall fuse system. The purpose of this system, referred to as the seismic infill wall isolator subframe (SIWIS) system, is to prevent damage to columns or infill walls due to infill-frame interaction through a “sacrificial” component or a “structural fuse.” The SIWIS system conceptually consists of two vertical and one horizontal sandwiched light-gauge steel studs with SIWIS elements in the vertical members. The experimental study presented here involves the in-plane lateral load testing of a two-bay three-story steel frame in three forms of bare frame, infilled braced frame, and pinned frame equipped with the proposed SIWIS device. In addition, a brick wall in-plane strength test and a series of component tests on three different designs for fuse element were conducted. In the conducted tests, the suggested technique initially engages the infill walls in seismic resistance of the frame, but ultimately isolates them. It is concluded, thus, that the proposed fuse system has the potential for the development of an effective way to reduce earthquake damage in framed buildings with infill walls.     

160MPa级抗震用低屈服点钢的研究与应用

通过合理的成分设计及轧制工艺选择,宝钢开发了160 MPa级抗震用低屈服点钢BLY160。研究表明:BLY160钢具有良好的韧性、极高的延伸率,并且焊接、加工性能良好,同时具有优良的低周疲劳性能,完全满足抗震阻尼器的制作需要,以提高建筑物的抗震能力。     

组合式钢框架内填预制RC墙结构静力性能有限元分析

钢框架内填预制钢筋混凝土剪力墙结构是新型混合式结构,由钢框架与内填墙组成双重防线,具有良好的抗侧力能力,同时预制构配件和预制装配建筑有利于推动住宅产业化发展.考虑大尺寸内填预制RC墙运输和安装困难的情况,提出竖向和横向组合式钢框架内填RC墙结构,采用ABAQUS建立有限元模型进行结构受力分析.通过分析荷载位移曲线,构件应力分布和变形情况,研究结构破坏特点和受力性能.结果表明,全螺栓结构因其合理的传力路径,有良好的承载力和延性;竖向组合式具有较好的初始刚度和整体承载力,与全螺栓连接预制RC墙有近似的受力性能,便于运输和安装;而横向组合式由于上下板缺乏有效传力路径,初始刚度和最终承载力都明显低于全螺栓和竖向组合式,不利于实际工程应用.      

Investigation of Seismic Behavior and Infill Wall Effects for Prefabricated Industrial Buildings in Turkey

Recently, Turkey has been hit by several moderate to large earthquakes that resulted in significant loss of life and property. The 1998 Adana and 1999 Marmara earthquakes caused severe damage not only in residential buildings but also in industrial buildings. Most of the industrial buildings in Turkey are constructed as prefabricated structures. Prefabricated structures are preferred because of their economic and rapid production. In the present study, the earthquake behavior and infill wall effects for single story hinged industrial prefabricated buildings were investigated. Nonlinear pushover, performance-based, time history, and fragility analyses were carried out for a sample prefabricated industrial building. Infill wall effect was investigated by adopting a diagonal strut model. The structural behavior and load-deformation relationship of prefabricated industrial buildings both with and without infilled walls were evaluated and compared. Results of the study show that masonry infill walls can affect the lateral load-carrying capacity and modify the earthquake response of prefabricated industrial buildings.     

低屈服点钢在建筑抗震设计中的应用

随着钢结构建筑抗震设计水平的进步,消能抗震设计已成为建筑抗震的一个发展方向.低屈服点、极低屈服点钢具有良好的塑韧性和低达100 MPa的屈服强度,并具有较狭窄的强度波动范围,而且成本低、易维护更换,在抗震阻尼构件的制造应用中具有显著的优势,从而成为建筑抗震材料中越来越受到重视的新钢种.介绍了抗震用低屈服点钢的性能要求及其作为抗震用钢的优点,同时还介绍了低屈服点钢的发展历史、现状及市场前景.     

21st Century Niobium-Bearing Structural Steels

Value-added applications of niobium (Nb) microalloyed steels continue to be developed for commercial implementation to meet increased material demands and improved properties for 21st century structural applications. These applications demand Nb-bearing steels that deliver improved toughness, fracture and fire resistance and weldability. Such applications include medium and jumbo beam, boiler, bridge, container, heavy equipment, long product, pressure vessel, ship, storage tank and windtower applications. Steel producers are challenged to develop microalloyed steel grades that cost effectively meet end user demands for higher strength at thinner cross sections, better low temperature toughness to resist brittle fracture in building, pressure vessel and ship structures, sustain higher loads per unit area in earthquake and hurricane zone product applications, demonstrate improved fire-resistance in buildings, bridges and tunnels and provide overall improved weldability. Niobium is often a key element to achieve these results. This paper will discuss Nb market opportunities and key operational practices required to successfully melt, cast and roll these high strength steel grades. Niobium process metallurgy is important to leverage the ability of niobium to obtain ultra-fine grain, homogeneous structural steel microstructures with superior mechanical properties. The process metallurgy, physical metallurgy and resultant properties are significantly determined by mill capabilities, mill practices, operational understanding and the culture of the steel mill. The optimal combination and implementation aspects that are unique to each mill we call metallurgical operational integration (MOI) . MOI is the bridge that links the product requirements to mill capability and process implementation.     

角钢屋架的高度经济分析

对一般受力状态下，八度地震区，有重级工作制吊车厂房角钢屋架的经济高度进行分析。     

Explosion and Fire Analysis of Steel Frames Using Mixed Element Approach

This paper presents a mixed element approach for analyzing steel frame structures subjected to a localized explosion and followed by fire. Critical members that are subjected to direct action of explosion and fire are modeled using shell elements. Noncritical members that are away from the affected area are modeled using beam elements. The proposed approach is computationally efficient for modeling large-scale structures and accurate enough to capture detailed behavior of member inelasticity and instability associated with the effects of blast and fires. Section classification may change from static load to blast load because of the enhanced yield strength due to high strain rate. The beam element approach is found to overpredict the overall resistance of steel frame structures if local deformation of cross section occurred after the blast loads. Detailed finite element modeling of critical frame members is necessary to improve the accuracy of predicting the ultimate resistance of structures. The proposed approach is applied to study the ultimate behaviors of a steel column and a three-story steel frame under explosion and fire.     

Performance of Masonry Stone Buildings during the March 25 and 28, 2004 A?kale (Erzurum) Earthquakes in Turkey

This paper reviews the performance of stone masonry buildings during the March 25 and 28, 2004, A?kale (Erzurum) earthquakes. A?kale is a township located 35?km from Erzurum city in Turkey. A majority of the buildings in the affected region are built in masonry. Most of the masonry buildings were formed with random or coursed stone walls without any reinforcement supporting heavy clay tile roofing over wooden logs. A large number of such buildings were heavily damaged or collapsed. The cracking and failure patterns of the buildings are examined and interpreted relative to current provisions for earthquake resistance of masonry structures. The damages are due to several reasons such as site effect, location, and length of the fault, and the poor construction quality of the buildings. In addition to these reasons, the two earthquakes hit the buildings within three days, causing progressive damage. Low strength stone masonry buildings with mud mortar are weak against earthquakes, and should be avoided in high seismic zones.     

Causes of Collapse and Damage to Low-Rise RC Buildings in Recent Turkish Earthquakes

This study assesses performance objectives defined in the Turkish Earthquake Code (TEC) in order to make a realistic evaluation related to heavy damage and collapse reasons of reinforced concrete (RC) buildings that experienced severe earthquakes in Turkey. A series of three-dimensional RC buildings with different characteristics and representing low-rise structures damaged and collapsed in the earthquake areas is designed according to Turkish codes (Turkish Design Standards and Turkish Earthquake Code). Pushover analyses are carried out to determine nonlinear behavior of the buildings under earthquake loads. Building performances are determined by using the displacement coefficients method, which is a commonly used nonlinear static evaluation procedure for different seismic hazard levels defined in the TEC. The stipulated performance objectives in the TEC are checked in terms of plastic rotations and maximum story drift. From the results of this research, it can be concluded that low-rise RC buildings designed according to Turkish codes sufficiently provide for the performance objectives stipulated in the TEC. Reasons for the heavy damages and collapses of RC buildings during severe earthquakes are explained by commonly occurring themes (i.e., project errors, poor quality of construction, modifications of buildings, etc.).     

Estimation of Maximum Roof Displacement Demands in Regular Multistory Buildings

For approximate estimation of the maximum inelastic roof displacement demand for existing multistory buildings, the current displacement coefficient method uses the maximum linear elastic displacement of the first-mode single-degree-of-freedom (SDOF) system corresponding to the buildings. The statistics of the SDOF system estimate of the roof displacement on the following topics are presented by three SAC steel buildings subjected to 72 earthquake ground motions recorded on firm sites. (a) How uncertain is the first-mode SDOF system estimation of the roof displacement? (b) What are the main sources of uncertainty in the estimation of the roof displacement? (c) How can the uncertainty be reduced? It is shown from the study that the maximum inelastic roof displacement demand of multistory buildings can be more accurately and more directly estimated by the maximum inelastic displacement of the first-mode elastoplastic SDOF system. This is especially true for low-rise buildings.     

Predictive Optimal Linear Control of Elastic Structures during Earthquake. Part I

A predictive optimal linear control (POLC) algorithm is proposed for controlling the seismic responses of elastic structures. This algorithm compensates for time delay that occurs in real control application by predicting the structural response in the classical optimal linear control equation. The unique feature of this proposed POLC algorithm is that it compensates for time delay very effectively over a very wide range of time delay magnitudes. Numerical examples of single-degree-of-freedom structures are presented to study the performance of the proposed POLC system for various time delay magnitudes. Results show that a time delay always causes degradation of control efficiency, and POLC can greatly reduce this degradation. The effects of natural periods and damping of the structure, different earthquake characteristics and numerical integration schemes, and choices of control gains on the degradation induced by time delay are carefully studied in the analysis. Results show that using a larger time delay magnitude may give smaller structural responses, and this magnitude is independent of earthquake characteristics but dependent on the control gains. Finally, practical application of POLC is performed on a six-story moment-resisting steel frame. It is demonstrated that POLC maintains stability in multi-degree-of-freedom structures and at the same time it has a satisfactory control performance.     

High Strength Low Alloy (HSLA) Steels in Building Construction

Majority of the buildings,including industrial buildings,are constructed using either structural steel (plates and structural shapes) or deformed bar steel reinforced concrete.Such buildings,however,must be designed to be safe and serviceable during construction and during use and occupancy.These objectives can be easily achieved by the use of steels having superior mechanical properties,ductility,weldability,fire resistance,etc.Over the years,the steel industry has made improvements in steel making technologies resulting in high strength low alloy (HSLA) steels with superior steel properties well suited for building construction.First part of this paper presents the structural design considerations,and the constructional considerations associated with the building structures in general,and steel structures in particular.This second part of the paper looks at the acceptance criteria for HSLA steels for North American building codes and construction.The third part of the paper presents the structural properties of currently available HSLA steels for building construction.The discussion focuses on hot-rolled structural steel shapes as well as deformed steel bars for concrete reinforcement.The paper argues that Niobium microalloying is the key to achieving superior properties in such steels.