Seismic Vulnerability Assessment of an Infilled Reinforced Concrete Frame Structure Designed for Gravity Loads

In the last decades, particular attention has been paid to the seismic vulnerability of existing reinforced concrete buildings designed for gravity loads only. Such buildings, designed before the introduction of capacity design in modern seismic codes, are very common, particularly in seismic prone countries of the Mediterranean area. Due to poor detailing and lacking of capacity design principles, high vulnerability has been highlighted in several past studies. In this article, inadequate seismic response and peculiar damage pattern are investigated by means of shake table tests performed on a 1:2 scaled 3-story infilled prototype. Particular attention is given to the role of beam-column joints and frame-panel interaction. The effectiveness of the EC8-based assessment approach is then evaluated; both linear and nonlinear numerical models, with different levels of sophistication, have been implemented in order to explore their behavioral aspects.     

Pushover Analyses of Hand-Loaded Steel Storage Shelving Racks

Among the various types of industrial solutions used to store goods and products, the light duty hand loaded shelving rack (SR) typology represents a very popular solution for domestic applications, libraries and for superstores/markets open to the public. Despite the limited cost, an eventual collapse could result in significant damage of stored goods, injuries, and potentially the loss of human life, with the possible consequence of a long suspension of commercial activities. This reflects directly on the great importance of a correct design that, despite the large use of SRs, is nowadays developed with approaches characterized by inadequate levels of reliability.

A research program on SRs is currently in progress in Italy, with the aim of improving the rules for both static and seismic design and this article presents a combined experimental-numerical study. Both component and pushover tests have been carried out, that are shortly summarized. Overall frame response has been simulated by means of advanced finite element software able to capture key features of the nonlinear response of slender frames with mono-symmetric cross-section members.     

Full-Scale Shaking Table Tests on a Substandard RC Building Repaired and Strengthened with Post-Tensioned Metal Straps

The effectiveness of a novel Post-Tensioned Metal Strapping (PTMS) technique at enhancing the seismic behavior of a substandard RC building was investigated through full-scale, shake-table tests during the EU-funded project BANDIT. The building had inadequate reinforcement detailing in columns and joints to replicate old construction practices. After the bare building was initially damaged significantly, it was repaired and strengthened with PTMS to perform additional seismic tests. The PTMS technique improved considerably the seismic performance of the tested building. While the bare building experienced critical damage at an earthquake of PGA = 0.15 g, the PTMS-strengthened building sustained a PGA = 0.35 g earthquake without compromising stability.     

Fuzzy-Sliding-Mode Supervisory Control of a Seismic Shake Table with Variable Payload for Robust and Precise Acceleration Tracking

Precise tracking of the earthquake acceleration profile in the presence of uncertainties is a challenge for the shake table control design. Design and implementation of a fuzzy-sliding-mode super- visory controller for an electric seismic shake table with variable payload is addressed in this paper. The proposed controller contains two layers including a proportional–integral loop and a fuzzy-sliding-mode supervisory controller. The controller is then implemented in the shake table and its performance is evaluated. The test results reveal successful performance of the proposed controller at robust tracking of some harmonic and seismic excitations in the presence of parametric uncertainties.     

Seismic Response of Secondary Systems Supported by Torsionally Yielding Structures

Substantial damage sustained during several recent earthquakes was non structural in nature. The economic consequence in terms of non structural component damage far exceeded the structural damage. Currently, there are several analytical studies that address the interaction between non structural components or Secondary systems (S-systems) and the main supporting structure or Primary system (P-system). Only a few of these analytical approaches have been proposed to evaluate and characterize the response of the S-systems attached to torsionally coupled P-systems. In addition, the experimental verification for the analytical approaches is scarce.

In the current study, the results and observations of an experimental research program conducted to characterize the behavior of both stiffness eccentric and mass eccentric torsionally coupled Primary-Secondary systems (PS-systems) are presented. From this experimental investigation it was found that the torsional yielding of the primary system has significant implications on the deamplification of near tuned secondary system response. The location of the S-system mounted on the P-system affects the peak response amplification, and interaction with the coupled P-system.     

Lessons Learned from Seismic Analysis of a Seven-Story Concrete Test Building

A uniaxial shake table test of a full-scale slice of a seven-story reinforced concrete wall building was performed at the University of California, San Diego. A 2D analytical model that primarily employed fiber-based beam-column elements was used for a blind prediction of the global response of the building to the imposed input accelerations. An improved analytical model, which adequately simulates the building's dynamic response and comparison of measured and analytical results, is presented. The lessons learned from participation in the blind prediction with particular attention to the effects of issues commonly ignored in analytical modeling of concrete buildings are included.     

Direct Acceleration Feedback Control of Shake Tables with Force Stabilization

This study presents a new strategy for shake table control that uses direct acceleration feedback without need for displacement feedback. To ensure stability against table drift, force feedback is incorporated. The proposed control strategy was experimentally validated using the shake table at the Johns Hopkins University. Experimental results showed that the proposed control strategy produced more accurate acceleration tracking than conventional displacement-controlled strategies. This article provides the control architecture, details of the controller design, and experimental results. Furthermore, the impact of input errors in shake table testing on the structural response is also discussed.     

A Base Isolation System for Developing Countries Using Discarded Tyres Filled with Elastomeric Recycled Materials

This article studies the performance of economic base isolators using tyres filled with elastomeric recycled materials. The research was conducted to analyze base isolators to be used in developing nations, where the application of conventional elastomeric rubber bearings due to economic reasons is limited.

The tested isolators are made of kart tyres filled with different recycled elastomeric materials and aggregates. Dynamic and static tests proved acceptable vertical to horizontal stiffness ratio of the bearings and shake table tests showed an excellent enhancement of the base isolated structural response compared to the corresponding fixed base structure.     

浙江越窑青瓷标本信息数据库管理系统的设计与实施

对文物标本进行系统分析归纳是传统工艺研究的必要途径,为实现越窑青瓷标本资料的资源共享,提高实验室工作效率,实现分析数据的科学管理,本研究开发设计了“浙江越窑青瓷标本信息数据库管理系统”.该系统基于B/S结构模式,以浙江省博物馆陶瓷标本中心的各类越窑瓷片标本来源、形态、化学成分、物理性能、显微结构、制作工艺等相关信息数据为基础,采用Wi ndows平台,以Visual Studi0 2010为开发环境,结合ASP.NET 4.0框架以及SQL Server数据库技术而构架.经过系统测试和实际运行证明,此管理系统具有良好的应用界面,交互性强,运行稳定,数据处理方便等优势,对实现古陶瓷研究信息资源共享,全面开展越窑青瓷的科学化研究提供了一个良好的数据平台.