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

The use of post-tensioned masonry can lead to economic and elegant structur es. 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 tend ons, the corrosion problem would be overcome. However, a number of issues n eed to be resolved before CFRP tendons can be used comfortably in posttensi oning applications. The first part of this paper deals with a diaphragm wal l post-tensioned using CFRP tendons. The post-tensioning procedures are des cribed and the prestress losses occurring in the past 12 months are present ed. 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 m odification could be applied to the design of any CFRP post-tensioned mason ry wall. A design example is included.