Vulnerability assessment and feasibility analysis of seismic strengthening of school buildings

The majority of structures in seismic-prone areas worldwide are structures that have been designed either without seismic design considerations, or using codes of practice that are seriously inadequate in the light of current seismic design principles. In Cyprus, after a series of earthquakes that occurred between 1995 and 1999, it was decided to carry out an unprecedented internationally seismic retrofitting of all school buildings, taking into account the sensitivity of the society towards these structures. In this paper representative school buildings are analysed in both their pristine condition and after applying retrofitting schemes typical of those implemented in the aforementioned large-scale strengthening programme. Non-linear analysis is conducted on calibrated analytical models of the selected buildings and fragility curves are derived for typical reinforced concrete and unreinforced masonry structures. These curves are then used to carry out a feasibility study, including both benefit-cost and life-cycle analysis, and evaluate the effectiveness of the strengthening programme

Bridge Active Monitoring for Maintenance and Structural Safety

An innovative approach, defined by the term “Active Monitoring”, has been designed and implemented by the Company ARCOS Engineering for a steel suspended arch bridge, starting from its design phases, for the sake of structural control and maintenance operations. The structure has a span of 250 m with a central arch that supports the runway through steel tendons. The bridge deck consists of a central beam and cantilevered lanes. The bridge has been instrumented with load cells at suspension cables, high precision servo inclinometers, steel surface temperature, differential pressure and humidity sensors, triaxial accelerometers. Data from sensors are the input of a finite element computational engine that evaluates derived quantities. Then, the coherence between the acquired and computed quantities is verified. Warning signals are provided if this check is not met. In this manner, a real-time structural assessment is carried out in a fully automated way, highlighting potential anomalies without human interaction. Therefore, this strategy becomes a valuable support for management and maintenance planning of infrastructure assets. The paper illustrates the layout and implementation of the system as well as some of the results that have been attained

Introduction

This chapter introduces the background and presents an overview of this book. Basically, engineering structures are required to satisfy predefined performance targets such as successfully resisting external load actions. Due to the randomness nature of both the structural property and the external attacks, however, the “absolute safety” of a structure cannot be achieved in engineering practice. Rather, the practical strategy is to control the probability of violating the performance requirements (e.g., structural safety) under an acceptable level. To that end, some probability-based approaches are essentially needed to quantify the occurrence possibility of such undesired consequences. Under this context, the mathematical formulation of analytical tools for structural reliability assessment is the topic of this book

An approach to the detection of post-seismic structural damage based on image segmentation methods

\u3cp\u3eCrack detection is critical in ensuring basic structural security, however manual identification of cracks is time-consuming and is subject to the judgments of reviewers. This research presents a crack detection technique based on image processing. The digital image processing is divided into different phases and each of them follow techniques that improve the quality of the images. In the segmentation phase, images traits need to be highlighted. This document portrays the image segmentation of a set of digital photographs of cracks and crevices of the different structures of the buildings of the faculties of the University of Guayaquil. In this study, a function is developed using the computational tool, Matlab, to obtain results by submitting the images to the different segmentation techniques applied during the investigation, for which methods are proposed such as: The Canny transform, The Sobel Operator and the Prewitt Transform. With the obtained results, crack measurement is applied based on the manual selection of pixels in order to generate damage assessment.\u3c/p\u3

Time-dependent reliability assessment

This chapter discusses the approaches for structural time-dependent reliability assessment. The significant difference between the time-dependent reliability and the classical reliability (c.f. Chap. 4 ) is the involvement of the time-variant characteristics in the analysis, where the variation of both the structural resistance and the external loads on the temporal scale should be reasonably modelled. This chapter starts from the motivation of time-dependent reliability assessment, followed by the modelling techniques of the resistance deterioration and the external load processes. Both the discrete and continuous load processes are discussed. Subsequently, the time-dependent reliability assessment approaches in the presence of both the discrete and the continuous loads are addressed. The comparison between the reliabilities associated with the two types of load processes is also presented