Sabrina Fawzia

An Improved Method to Detect Damage Using Modal Strain Energy Based Damage Index

This paper presents two novel concepts to enhance the accuracy of damage detection using the Modal Strain Energy based Damage Index (MSEDI) with the presence of noise in the mode shape data. Firstly, the paper presents a sequential curve fitting technique that reduces the effect of noise on the calculation process of the MSEDI, more effectively than the two commonly used curve fitting techniques; namely, polynomial and Fouriers series. Secondly, a probability based Generalized Damage Localization Index (GDLI) is proposed as a viable improvement to the damage detection process. The study uses a validated ABAQUS finite-element model of a reinforced concrete beam to obtain mode shape data in the undamaged and damaged states. Noise is simulated by adding three levels of random noise (1%, 3%, and 5%) to the mode shape data. Results show that damage detection is enhanced with increased number of modes and samples used with the GDLI.

Double strap joint tests to determine the bond characteristics between CFRP and steel plates

Advanced composite materials offer remarkable potential in the upgrade of civil engineering structures. The evolution of CFRP (carbon fibre reinforced polymer) technologies and their versatility for applications in civil constructions require comprehensive and reliable codes of practice. Guidelines are available on the rehabilitation and retrofit of concrete structures with advanced composite materials. However, there is a need to develop appropriate design guidelines for CFRP strengthened steel structures. It is important to understand the bond characteristics between CFRP and steel plates. This paper describes a series of double strap shear tests loaded in tension to investigate the bond between CFRP sheets and steel plates. Both normal modulus (240 GPa) and high modulus (640 GPa) CFRPs were used in the test program. Strain gauges were mounted to capture the strain distribution along the CFRP length. Different failure modes were observed for joints with normal modulus CFRP and those with high modulus CFRP. The strain distribution along the CFRP length is similar for the two cases. A shorter effective bond length was obtained for joints with high modulus CFRP whereas larger ultimate load carrying capacity can be achieved for joints with normal modulus CFRP when the bond length is long enough.

Durability performance of carbon fibre-reinforced polymer strengthened circular hollow steel members under cold weather

The use of circular hollow steel members has attracted a great deal of attention during past few years because of having excellent structural properties, aesthetic appearance, corrosion and fire protection capability. However, no one can deny the structural deficiency of such structures due to reduction of strength when they are exposed to severe environmental conditions such as marine environment, cold and hot weather. Hence strengthening and retrofitting of structural steel members is now very imperative. This paper presents the findings of a research program that was conducted to study the bond durability of carbon fibre-reinforced polymer (CFRP) strengthened steel tubular members under cold weather and tested under four-point bending. Six number of CFRP-strengthened specimens and one unstrengthened specimen were considered in this program. The three specimens having sand blasted surface to be strengthened was pre-treated with MBrace primer and other three were remained untreated and then cured under ambient temperature at least four weeks and cold weather (3 C) for three and six months period of time. Quasi-static tests were then performed on beams to failure under four-point bending. The structural response of each specimen was predicted in terms of failure load, mid-span deflection, composite beam behaviour and failure mode. The research outcomes show that the cold weather immersion had an adverse effect on durability of CFRP-strengthened steel structures. Moreover, the epoxy based adhesion promoter was found to enhance the bond durability in plastic range. The analytical models presented in this study were found to be in good agreement in terms of predicting ultimate load and deflection. Finally, design factors are proposed to address the short-terms durability performance under cold weather.

Effects of CFRP layer orientation on strengthening of hollow steel elements

U ovom se radu proučavaju utjecaji orijentacije slojeva CFRP traka (polimera ojačanih ugljičnim vlaknima) na poboljšanje nosivosti ojačanih čeličnih kružnih šupljih elemenata. Provedeno je ispitivanje savijanjem uz djelovanje sila u četiri točke, a elementi su opterećeni na savijanje do sloma. Poboljšanje nosivosti ojačanih cijevnih čeličnih elemenata analizirano je s obzirom na silu otkazivanja, krutost, kompozitno djelovanje i vrstu sloma. Nosači armirani CFRP trakama s dva uzdužna sloja i jednim po obodu pokazuju bolje ponašanje od nosača armiranih s jednim uzdužnim slojem i dva sloja po obodu.This paper reveals the effects of layer orientation on structural behaviour of three layers configured (LHL, HHL, LLH) CFRP strengthened circular hollow section (CHS) members subjected to bending. The beams were loaded to failure under four-point bending. The structural behaviour of the CFRP strengthened tubular steel beams with various layer orientations were presented in terms of failure load, stiffness, composite beam action and modes of failure. The LHL and LLH layers oriented strengthened beams perform slightly better than HHL layers oriented strengthened beams. The LHL and LLH layers oriented treated beams showed very similar structural behaviour.

3 – Food Microstructure as affected by processing and its effect on quality and stability

Fundamental understanding of the microstructure is required to predict and describe the changes in food quality during any food processing. Recent advancement in microscopy and image processing technology has helped food engineers probe into the microstructure of food materials. Moreover, food scientists have also gathered a large amount of quantitative data for establishing the relationship between the food microstructure and the food quality. This chapter discusses how food microstructure is affected by food processing conditions, particularly during drying. It also presents a relationship between food microstructure and the changes in food properties and quality attributes during food processing.

Barriers to implementing lean construction practices in the Kingdom of Saudi Arabia (KSA) construction industry

Purpose The purpose of this paper is to identify the barriers to implementing lean construction in the Kingdom of Saudi Arabia (KSA) construction industry and to prioritise the principal factors that constitute these barriers. Design/methodology/approach A literature review was initially used to reveal the global barriers to implementing lean construction. Subsequently, these barriers were incorporated into a structured questionnaire, and a convenience sample of 282 construction professionals in the KSA construction industry was surveyed. The results were analysed using mean item score (MIS), Mann–Whitney U test and principal component analysis (PCA). Findings The findings revealed 22 barriers to lean construction implementation in the KSA construction industry. Principal factors that constitute these barriers were found to be traditional practices, client related, technological, performance and knowledge and cost-related barriers in descending order of pervasiveness. The study also proposes solutions to overcome these principal barriers. Originality/value This study provides a global overview of the barriers to implementing lean construction. It contributes to the body of knowledge, as it uncovers for the first time the barriers to implementing lean construction in the KSA construction industry with reference to the socio-cultural, economic and operational context of the KSA. Thus, it is relevant to other countries in the Middle East because of their shared similarities to the KSA. Furthermore, the solutions proposed to overcome these barriers in the KSA construction industry can be applied in other countries where similar barriers are identified.