Examination of high strength steel design provisions : bond

• Main Author: Chua, Aye Neng
• Other Authors: Li Bing
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2020
• Subjects: Engineering::Civil engineering::Structures and design
• Online Access: https://hdl.handle.net/10356/136731
• Institution: Nanyang Technological University

This project aims to provide a comprehensive comparison among seven deterministic bond stress-slip models developed in the past research, and to enhance their applicability by establishing the bond-slip statistical cloud model. This project focuses on the bond-slip design model for unconfined reinforced concrete using high strength steel governed by splitting failure. Seven deterministic bond stress-slip models and 368 sets of experimental specimens that exhibit splitting failures had been collected from literatures. Modelling of error was conducted in terms of qualitative and quantitative analysis. In the context of qualitative analysis, graphical comparisons between the analytical and empirical bond-stress slip curve were carried out. In addition, characteristic points such as peak bond stress had been compared with the analytical results. Meanwhile, for the case of quantitative analysis, integral absolute errors (IAE) were computed. Two best performed models were selected for development of bond-slip cloud model in later stage. In addition, two statistical parameters, namely expected values and standard deviations of ultimate bond stresses were determined for the establishment of the bond-slip cloud models. Finally, the enhanced models were compared with experimental specimens and the best performed one was chosen to be the final proposed model in this project. This report has also conducted an analysis on two factors affecting the bond strength, namely, concrete compressive strength and development length provision in the unconfined reinforced concrete (RC) structure. The study compared the effect of concrete capacity on bond strength by using normal strength concrete and high strength concrete in the analysis. Furthermore, as yield strength of reinforcement steel embedded in concrete is equally important on the bond strength, a study is carried out using specimens data with normal strength steel and high strength steel to examine the provision of development length in each category of steel. Five international codes were used to predict the development length, and the codes provisions were compared against the experimental values. Subsequently, one code will be recommended separately for the prediction of different combination of RC structure, an example would be high strength concrete with normal strength steel. Finally, limitations and recommendations for future studies regarding this field of research were discussed.