Khaled Ghaedi

RECENT DEVELOPMENTS IN DAMAGE IDENTIFICATION OF STRUCTURES USING DATA MINING

CIVIL STRUCTURES ARE USUALLY PRONE TO DAMAGE DURING THEIR SERVICE LIFE AND IT LEADS THEM TO LOSS THEIR SERVICEABILITY AND SAFETY. THUS, DAM-AGE ASSESSMENT CAN GUARANTEE THE INTEGRITY OF STRUCTURES. AS A RESULT, A STRUCTURAL DAMAGE DETECTION APPROACH INCLUDING TWO MAIN COMPONENTS, A SET OF ACCELEROMETERS TO RECORD THE RESPONSE DATA AND A DATA MINING (DM) PROCEDURE, IS WIDELY USED TO EXTRACT THE INFORMATION ON THE STRUCTURAL HEALTH CONDITION. IN THE LAST DECADES, DM HAS PROVIDED NUMEROUS SOLUTIONS TO STRUCTURAL HEALTH MONITORING (SHM) PROBLEMS AS AN ALL-INCLUSIVE TECHNIQUE DUE TO ITS POWERFUL COMPUTATIONAL ABILITY. THIS PAPER PRESENTS THE FIRST ATTEMPT TO ILLUSTRATE THE DATA MINING TECHNIQUES (DMTS) APPLICATIONS IN SHM THROUGH AN INTENSIVE REVIEW OF THOSE ARTICLES DEALING WITH THE USE OF DMTS AIMED FOR CLASSIFICATION-, PREDICTION- AND OPTIMIZATION-BASED DATA MINING METHODS. ACCORDING TO THIS CATEGORIZATION, APPLICATIONS OF DMTS WITH RESPECT TO SHM RESEARCH AREA ARE CLASSIFIED AND IT IS CONCLUDED THAT, APPLICATIONS OF DMTS IN THE SHM DOMAIN HAVE INCREASINGLY BEEN IMPLEMENTED, IN THE LAST DECADE AND THE MOST POPULAR TECHNIQUES IN THE AREA WERE ARTIFICIAL NEURAL NETWORK (ANN), PRINCIPAL COMPONENT ANALYSIS (PCA) AND GENETIC ALGORITHM (GA), RESPECTIVELY.

Seismic isolation retrofitting solution for an existing steel cable-stayed bridge

This paper investigated the seismic retrofitting of an existing cable-stayed bridge through the use of a seismic isolation system. The bridge is situated in a high seismic zone. During the Saguenay earthquake 1988, one of the anchorage plates of the bridge supports failed. Herein, several configurations of seismic isolation system were considered to identify an appropriate solution for the seismic retrofitting of the bridge in both the longitudinal and transverse directions. A three-dimensional model of the bridge was created, and its seismic behavior studied through nonlinear dynamic time-history analysis. The comparative performance study among the five retrofitting configurations showed that the partial seismic isolation of the bridge led to an enhancement of the seismic response of the bridge in one direction only. However, the overall seismic response of the cable-stayed bridge substantially improved in the longitudinal and transverse directions in cases where the isolation systems were utilized between the supports and the deck-tower connection of the bridge.

Experimental Study of a New Bar Damper Device for Vibration Control of Structures Subjected to Earthquake Loads

ABSTRACT A new yielding damper, called Bar Damper (BD), made of a number of solid bars sandwiched between two plates is introduced in this paper. Based on a simplified mechanical modeling, design parameters were formulated. The device is shown to have stable hysteretic behavior under cyclic loads. The device is capable of undergoing large displacements without significant strength and stiffness degradation. The slenderness ratio of the bars is a crucial design parameter controlling the effective stiffness and energy dissipation capacity of the dampers. Strength of the devices estimated from theoretical models developed herein is found to be consistent with experimental results.

Seismic Response Analysis of Fully Base-Isolated Adjacent Buildings with Segregated Foundations

In populous cities, construction of multistorey buildings close to each other due to space limitation and increased land cost is a dire need. Such construction methods arise several problems during earthquake excitation. The aim of this study is to investigate the bidirectional seismic responses of fully base-isolated (FBI) adjacent buildings having different heights and segregated foundations. Therefore, two scenarios, namely, (a) investigation of the responses of FBI adjacent buildings compared to those with fixed base (FFB) and (b) the effects of separation distance on FBI adjacent buildings, were studied. Based on these investigations, the results showed that isolation system significantly enhances the overall responses of the BI buildings. Spectacularly, the base isolation system was further efficient to decrease displacement rather than the acceleration. In addition, increase of the seismic gap changed the acceleration, pounding, base shear, base moment, and storey drift, as well as the force-deformation performance of the isolators. Therefore, it seems a need to focus on the effect of the separation distances for the design of base isolators for FBI adjacent buildings in future works.