Carbon fibre reinforced polymer (CFRP) post-tensioned masonry diaphragm walls: prestressing, behaviour, and design recommendations

Abstract

The use of post-tensioned masonry can lead to economic and elegant structures. A major problem associated with post-tensioning is the corrosion of the steel tendons, especially for unbonded tendons. If carbon fibre reinforced polymer (CFRP) tendons could be used to replace the traditional steel tendons, the corrosion problem would be overcome. However, a number of issues need to be resolved before CFRP tendons can be used comfortably in post-tensioning applications. The first part of this paper deals with a diaphragm wall post-tensioned using CFRP tendons. The post-tensioning procedures are described and the prestress losses occurring in the past 12 months are presented. Results from thermal, flexure, and racking shear tests performed on the wall are reported. The second part of the paper deals with the development of design procedures and equations based on both the test results and the database currently available. The equations presented are specifically for CFRP unbonded post-tensioned masonry diaphragm walls but with appropriate modification could be applied to the design of any CFRP post-tensioned masonry wall. A design example is included.Key words: anchorage system, carbon fibre reinforced polymers, diaphragm walls, flexural strength, masonry walls, prestress losses, prestressed masonry, post-tensioning, shear strength, thermal loads.