Seismic Damage Reduction of a Structural System based on Nontraditional Sliding Interfaces with Graphite Lubrication

In this paper, we propose a free-standing structure that is unanchored to its foundation and has a cost-efficient interface consisting of common construction materials (steel, mortar, and iron) with graphite lubrication; this structure is expected to behave as an earthquake-resistant structure during small earthquakes and a base-isolated structure during large earthquakes. To realize the structure, this study examined the frictions of the interfaces in shaking table tests. In addition, the seismic responses of the free-standing structures based on the interfaces were examined via incremental dynamic analyses with 44 ground motions and a simple model of typical Japanese steel structures.     

Influence of Openings,With and Without Confinement,on Cyclic Response of Infilled R-C Frames — An Experimental Study

This article presents the experimental results of a study on reinforced-concrete frames infilled with masonry with openings. The frames were designed according to current European codes. They were built in a scale 1:2.5 and infilled with masonry walls. Mid-size window and door openings were located centrically and eccentrically and were executed with and without tie-columns around them. Presence of masonry infill, although not accounted for in design, improved the system behavior (increase in stiffness, strength and energy dissipation capacity) at drift levels of up to 1%. During the test, openings did not influence the initial stiffness and strength at low drift levels. Their presence became noticeable at higher drift levels, when they lowered the energy dissipation capacity of the system. The infill wall had a multiple failure mechanism that depended on the opening height and position. Tie-columns controlled the failure type, independent of the opening type, prevented out-of-plane failure of the infill, and increased the system's ductility. Negative effects of the infill on the frame were not observed. The infill's contribution could be deemed positive as it enhanced the overall Structural Performance Level. Analytical expressions commonly used for infilled frames underestimate the infill's contribution to strength and stiffness and overestimate the contribution of the bare frame.     

Unruly topographies: unemployment, citizenship and land settlement in inter-war Wales

Between 1934 and 1939, over 5000 people, mainly ex-miners and their families, were settled in government-owned land settlements in England and Wales. This policy emerged as a response to mass unemployment, and complemented other schemes for the unemployed developed by the inter-war National Government. This paper will consider the geographical conditions that were imagined, realized and contested in these settlements. Acknowledging the hybrid and liminal nature of these spaces, the paper mobilizes new work in cultural and historical geography and draws out the heterotopic potential of the settlement programme.     

尺度政治中的空间重叠及其制度形态塑造研究——以深汕特别合作区为例

以深汕特别合作区为例,借鉴依赖空间和交互空间分析思路,对基于共同利益而非对抗性的尺度政治过程进行分析。其中,深圳市对连续依赖空间的建构、汕尾市对依赖空间交互功能的挖掘、广东省在交互空间中的管制试验等分别定义了它们各自的依赖空间和交互空间,这些空间在多个尺度上相互重叠,并集中体现在深汕特别合作区这一新的尺度和制度空间中。在这种情况下,各行动者依赖和交互空间的性质、行动者间的相对权力关系以及各自掌握的不同资源等因素共同塑造了合作区的组织架构、管理权限和利益分配等制度形态。     

金华市特殊教育现状的调查研究

特殊教育是对残疾人的一种教育,是社会的人本、民主、公平的反映,是国家及其文明程度的一个窗口。通过对浙江省金华市七所特殊教育学校现状的调查与研究,了解到近几年金华市的特殊教育有很大的发展,但是在办学规模、地理位置、师资力量、硬件设施等方面还存在不足,影响了学龄残疾儿童的入学率与特殊教育的发展速度。故立足于金华市特教的现实问题,提出具有可行性的方法与对策,促进金华市特殊教育事业更好更快的发展。     

Constant and Variable Amplitude Cyclic Behavior of Welded Steel Beam-to-Column Connections

This article presents a study on welded beam-to-column joints of moment-resisting steel frames. The main features of the joint specimens are summarised, in order to identify key parameters influencing the joint response as well as their low-cycle fatigue endurance. The cyclic behavior and the low-cycle fatigue strength of the connections were initially assessed by cyclic quasi-static testing, carried out at the Technical University of Milan. Analysis of the results has been carried out in order to verify the validity of a linear damage accumulation model combined with a low-cycle fatigue approach based on S-N lines concept. Moreover, a criterion to predict the type of failure and a procedure of appraising the fatigue endurance are presented and their validity proved by the results of variable amplitude tests.     

A Static Nonlinear Procedure for the Evaluation of the Elastic Buckling of Anchored Steel Tanks Due to Earthquakes

Ground-supported steel tanks experienced extensive damage in past earthquakes. The failure of tanks in earthquakes may cause severe environmental damage and economic losses. This study deals with the evaluation of the elastic buckling of above-ground steel tanks anchored to the foundation due to seismic shaking. The proposed nonlinear static procedure is based on the capacity spectrum method (CSM) utilized for the seismic evaluation of buildings. Different from the standard CSM, the results are not the base shear and the maximum displacement of a characteristic point of the structure but the minimum value of the horizontal peak ground acceleration (PGA) that produces buckling in the tank shell. Three detailed finite element models of tank-liquid systems with height to diameter ratios H/D of 0.40, 0.63, and 0.95 are used to verify the methodology. The 1997 UBC design spectrum and response spectra of records of the 1986 El Salvador and 1966 Parkfield earthquakes are used as seismic demand. The estimates of the PGA for the occurrence of first elastic buckling obtained with the proposed nonlinear static procedure were quite accurate compared with those calculated with more elaborate dynamic buckling studies. For all the cases considered, the proposed methodology yielded slightly smaller values of the critical PGA for the first elastic buckling compared to the dynamic buckling results.     

Seismic Demand on Shear Panel Dampers Installed in Steel-Framed Bridge Pier Structures

This study is aimed at investigating the demand on shear panel dampers (SPDs) installed in steel structures under strong earthquake motions to serve as guidance for the recommended capacity of SPDs in seismic design. For this purpose, an extensive dynamic analysis is carried out on steel bridge pier structures with SPD devices. To describe the restoring force characteristics of SPDs, the analysis uses a newly developed combined hardening model based on experimental data. The seismic demands made on SPD devices are examined and then summarized to give recommended values for determining the necessary deformation capacity of SPDs.     

Numerical Investigation of Residual Strength and Energy Dissipation Capacities of Corroded Bridge Members Under Earthquake Loading

Recent damage examples of aged steel bridge infrastructures around the world are so alarming. They intensified the importance of careful evaluation of existing structures for the feasibility of current usage and to ensure public safety. Corrosion and fatigue cracking may be the two most important types of damages in aging structures. Furthermore, recent earthquakes demonstrated potential seismic vulnerability of some types of steel bridges. Corrosion and its effects can trigger the damages caused by earthquakes, and it will be vital to understand the behavior of existing steel bridges which are corroding for decades in future severe seismic events as well. This article comprises the results of nonlinear FEM analysis of many actual corroded plates with different corrosion conditions and proposes a simple and reliable methodology to estimate remaining seismic strength and energy dissipation capacities by measuring only the minimum thickness of a corroded surface, which can be used to make rational decisions about the maintenance management plan of steel infrastructures.