EVALUATING AND PROPOSING PREDICTION MODELS OF SHEAR CRACK WIDTH IN CON- CORETE BEAMS Mohamed ZAKARIA 1 , Tamon UEDA 2 and Zhimin WU 3 1 Member of JSCE, Assistant Professor, South Valley University (Aswan, 81542, Egypt) E-mail: [email protected] 2 Fellow member of JSCE, Professor, Faculty of Engineering, Hokkaido University (Kita 13 Nishi 8, Kita-ku, Sapporo, 060-8628, Japan) E-mail: [email protected] 3 Professor, Dept. of Civil Engineering, Dalian University of Technology (Dalian, P. R. China) E-mail: [email protected] This paper presents a comprehensive review on the available prediction models in the literature to es- timate shear crack width in reinforced and prestressed concrete members by comparing shear crack open- ings calculated from prediction model with those obtained from seven experimental investigations to eva- luate their accuracy together with effectiveness of factors considered. As a result of this study, the models for the prediction of shear crack spacing and width in reinforced and prestressed concrete beams are proposed. The proposed models show a better correlation with all the test results compared to the other prediction models. The models can predict both average and maximum shear crack width and are applicable to fatigue loading. Key Words : reinforced concrete beam, prestressed concrete beam, shear crack spacing, shear crack width, shear reinforcement strain, side concrete cover to shear reinforcement 1. INTRODUCTION A number of investigations in recent years have been concerned with cracking behavior and crack control in reinforced concrete (RC) and prestressed concrete (PC) members, due to its harmful effects on structural performances such as serviceability and durability requirements. Cracks with excessive widths occurring in concrete structures can become a cause for reduction in durability due to reinforce- ment corrosion, deterioration in serviceability such as water/air-tightness and appearance, and poor maintainability, etc. The recent tendency toward utilizing the performance-based concept in design more efficiently is a driving force of the investiga- tions on crack control. The guidelines for crack control in practical de- sign codes are mostly meant for tensile and flexure crack width. They were experimentally obtained and cannot be applied directly to prediction of shear crack width, because shear crack is caused by a dif- ferent mechanism 1) . It is worthy to mention that some of the prescribed guidelines in existing practice codes 2), 3) recommend controlling shear crack width by paying more atten- tion to the shear reinforcement stress. These guide- lines provide certain limits for the maximum steel stress depending on the type of reinforcement. When the steel stresses under service loads do not exceed the allowable limits the resulting crack widths are deemed to be within the acceptable range. However, this would not be a sufficient way to control shear crack width. Many investigators 1), 4)~10) illustrated that shear reinforcement strain is not the only factor to control the shear crack width. Zakaria et al. 1) have explained well the shear cracking behavior by car- rying out a detailed experiment to show the effects of the various influential parameters on the shear crack spacing and the relationship between shear crack width and shear reinforcement strain at the intersec- tion with shear cracks. It was concluded that shear reinforcement characteristics, such as side concrete cover to shear reinforcement, shear reinforcement spacing and/or shear reinforcement configuration, Journal of Japan Society of Civil Engineers, Ser. E2 (Materials and Concrete Structures), Vol. 67, No. 2, 245-263, 2011. 245
EVALUATING AND PROPOSING PREDICTION MODELS OF SHEAR CRACK WIDTH IN CONCORETE BEAMS
May 19, 2023
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