Large-Scale Experimental Investigation on Mustafa Pasha Mosque

To evaluate the seismic stability of Mustafa Pasha Mosque in Skopje strengthened by an advanced mixed technology, shaking table tests were carried out on a model in scale 1:6. The investigation was performed within the activities of the Sixth Framework Program PROHITECH – “Earthquake Protection of Historical Buildings by Reversible Mixed Technologies”. To define the effectiveness of the proposed strengthening the testing procedure consisted of two main phases: testing of the original model and testing of the strengthened model. The observed seismic behavior and damage during each phase of the testing program were analyzed on the basis of the obtained experimental results.     

Equivalent Force Control Method for Real-time Testing of Nonlinear Structures

The equivalent force control (EFC) method replaces numerical iteration with a feedback control strategy to solve the nonlinear equations of motion using an implicit integration method for real-time substructure tests (RSTs). The method, however, requires the conversion of the equivalent forces to structural displacements using a conversion matrix. It is demonstrated in this article that with the use of a proportional-integral (PI) controller for the EFC, one has the convenience of choosing the initial stiffness matrix of a structure to construct the conversion matrix regardless of the properties and degree of nonlinearity of the system. The stability condition of the EFC using a PI controller has been derived with the Routh stability criterion. Methods for designing and tuning a PI controller for RST using EFC have been presented and excellent system performance has been obtained from numerical simulations and actual tests. The simulation results showed that the EFC method using a PI controller and the initial stiffness matrix to construct the conversion matrix can deliver excellent performance even for structural systems that develop a severe strain-softening behavior. Its superiority over iteration method proposed by Jung et al. [2007] Jung, R. Y., Shing, P. B., Stauffer, E. and Thoen, B. 2007. Performance of a real-time pseudo dynamic test system considering nonlinear structural response. Earthquake Engineering and Structural Dynamics, 36: 1785–1809.  [Google Scholar] was demonstrated through numerical simulation. This provides an efficient means to test nonlinear multiple-degrees-of-freedom structures.     

Jet-Pacs Project: Dynamic Experimental Tests and Numerical Results Obtained for a Steel Frame Equipped with Hysteretic Damped Chevron Braces

The experimental and numerical results obtained by Research Units of the University of Basilicata and University of Calabria for a steel frame, bare or equipped with metallic yielding hysteretic dampers (HYDs), are compared. The shaking table tests were performed at the Structural Laboratory of the University of Basilicata within a wide research program, named JETPACS (“Joint Experimental Testing on Passive and semiActive Control Systems”), which involved many Research Units working for the Research Line 7 of the ReLUIS (Italian Network of University Laboratories of Earthquake Engineering) 2005–2008 project. The project was entirely founded by the Italian Department of Civil Protection. The test structure is a 1/1.5 scaled two-story, single-bay, three-dimensional steel frame. Four HYDs, two for each story, are inserted at the top of chevron braces installed within the bays of two parallel plane frames along the test direction. The HYDs, constituted of a low-carbon U-shaped steel plate, were designed with the performance objective of limiting the inter-story drifts so that the frame yielding is prevented. Two design solutions are considered, assuming the same stiffness of the chevron braces with HYDs, but different values of both ductility demand and yield strength of the HYDs. Seven recorded accelerograms matching on average the response spectrum of Eurocode 8 for a high-risk seismic region and a medium subsoil class are considered as seismic input. The experimental results are compared with the numerical ones obtained considering an elastic-linear law for the chevron braces (in tension and compression), providing that the buckling be prevented, and the Bouc-Wen model to simulate the response of HYDs.     

Effect of AAC Infill Walls on Structural System Dynamics of a Concrete Building

The effect of autoclaved aerated concrete (AAC) infill walls on the structural system dynamics of a two-story reinforced concrete building is investigated using its finite element structural model, which is calibrated to simulate the acceleration-frequency response curves from its forced vibration test. The model incorporating the AAC infill walls by equivalent diagonal struts captures the increase in lateral stiffness of the building and the torsional motions induced due to the asymmetrically placed AAC infill walls. A higher strut width coefficient than in ASCE/SEI 41-06 is recommended to model the stiffness of the AAC infill walls in the elastic range.     

Transverse Seismic Behavior Studies of a Medium Span Cable-Stayed Bridge Model with Two Concrete Towers

Due to lack of investigation on nonlinear seismic behavior of cable-stayed bridges under strong earthquake excitation, the concrete towers, as the main gravity-carrying component, are usually required to remain nearly elastic. However, in order to achieve this high seismic performance objective, the reinforcement ratio of the tower legs and the tower struts need to be greatly increased in addition to its static loading requirement. To study the potential plastic region and possible failure mode of the cable-stayed bridge, a 1/20-scale full bridge model from a typical medium span concrete cable-stayed bridge was designed, constructed and tested on 4 linear shake tables using a site specific artificial wave in the transverse direction. Test results showed that the damage characteristics of the bridge model were as follows: (1) the severe damage was observed at the upper strut, with several steel bars fractured at both ends; (2) the repairable damage was observed at tower legs at the bottom and the middle part, with concrete cover spalling and exposure of steel bars; (3) the minimal damage was observed at the lower strut and the both sides of the side bents, with only slightly concrete spalling; and (4) no damage was observed at the auxiliary bents, the superstructure and the cables. Numerical results and test results were further compared and showed good agreement in low amplitudes of excitations. The test also proved that the bridge system was stable in flexural failure of upper struts, and had the negligible residual displacement subjected to high amplitudes of excitations.     

Seismic Resistant Effects of Composite Reinforcement on Rockfill Dams Based on Shaking Table Tests

In this article, the seismic resistant effect of a new reinforcement measure on rockfill dams, the Composite Reinforcement, is investigated based on 1-g large-scale shaking table tests. A 1 m high rockfill dam, which is scaled from the Yele rockfill dam in China, is tested by inputting a series of motions designed from a realistic Wenchuan earthquake record. The model dam is divided into two sections, with one section representing a normal rockfill dam (RD) while the other section employing the Composite Reinforcement (composite reinforced rockfill dam (CRRD)). The seismic-resistant effect of the Composite Reinforcement is investigated by comparing the recorded dynamic response of the two dams, in terms of the peak acceleration amplification factor distribution along the dam core, the crest settlement, and the visualized failure pattern. Results show that the application of the Composite Reinforcement can effectively mitigate the seismically induced deformation of the rockfill dam by reducing the peak crest acceleration and residual crest settlement by 18% and 55%, respectively, when subjected to a 0.5 g input motion. The investigation of the captured failure pattern on the two dams further indicates the effective reinforcing effect of the Composite Reinforcement on preventing the sliding failures of rockfill materials in the top 20% height of the dam body.     

馆藏浮放陶瓷文物地震摇晃响应振动台试验

为保护可移动文物,采取试验方法研究了地震作用下馆藏浮放文物的摇晃响应.以故宫某展柜为原型,制作了1∶1比例的模型,并在展柜内放置了一陶瓷文物,进行了振动台试验.通过白噪声激励,获得了展柜的基频;通过输入不同类型、不同强度的地震波,研究了展柜和文物的地震响应;通过数值模拟,从理论上对模型地震响应进行了进一步论证.结果表明:对展柜而言,其基频在29～35 Hz之间,与地震波卓越频率相差较大,因而在地震作用下摇晃不明显;对文物而言,在地震波强度较小时能保持稳定振动状态,而在地震波强度较大时,文物容易产生明显摇晃并导致倾覆.此外,数值模拟结果与振动台试验结果吻合,证明了试验方法的有效性.在实际工程中,对高宽比较大的文物,应采取适当的加固措施,以减轻其摇晃震害.     

Constituting Corporate Europe: A Study of Elite Social Organization

Abstract: This article explores the emerging shape and form of the European corporate community since 1996. We examine the cohesion of corporate Europe through the network of interlocking corporate directorates and memberships in the European Round Table of Industrialists. We focus on the unequal structure of representation; the interplay of national and transnational aspects of the network; the role of finance capitalists as a signpost of a regime of internationalized finance capital; and the embeddedness of corporate Europe in the global corporate network. Although the transnational European network gained in strength while national networks eroded, expansion of the European network did not negate a structure of representation favoring the northwest. Bankers became less dominant, yet industrialists with financial connections formed the core of the European corporate community, signaling a departure from national corporate communities centered upon banks. At the threshold of the current economic crisis, corporate Europe comprised the most integrated segment of the global corporate elite.     

单檐歇山式木构古建抵抗极端烈度地震试验调查研究

为更好地保护我国古建筑,基于《单檐歇山式古建筑抗震性能振动台试验》的相关成果,研究了强震作用下我国明清官式木构古建的抗震性能,制作了与该论文相同的试验模型,进行了振动台试验。通过对模型输入烈度逐渐增强的1940年El-centro波,并考虑地震波为水平双向作用,分析了强震作用下不同构造的试验现象,开展了详细的震后调查,获得了不同构造在强震作用下的抗震性能和震害机制。结果表明:强震作用下,我国明清官式木构古建的振动形式表现为柱架、斗拱、梁架及屋顶的近似同步往复摇摆;主要震害包括柱底偏移、榫卯节点开裂、拔榫、斗拱偏移及错位、额枋-垫板分离、墙体倒塌等,但承重木构架受损不严重,结构未产生倒塌。其良好抗震性能的原因与古建筑的构造特征密切相关。     

A Simplified Model to Evaluate the Dynamic Rocking Behavior of Irregular Free-Standing Rigid Bodies Calibrated with Experimental Shaking-Table Tests

A simplified model to evaluate the dynamic rocking behavior of free-standing irregular rigid bodies under earthquake-induced forces is proposed. The model analyzes the response of a three-dimensional irregular rigid body using a numerical approach that considers a critical section and two equivalent rectangular rigid blocks. Experimental shaking-table tests were carried out on modular prototypes, which allow the replication of representative mass distributions, sizes, and/or slenderness ratios for typical objects. The tests were used to calibrate the numerical model. It was found that the dynamic behavior under irregular conditions (asymmetrical shape and/or non-uniform mass distribution) can be estimated with the appropriate geometric and density considerations.