Study of the behaviour of post-tensioned brickwork beams

Abstract

This thesis presents the results of a study into the behaviour of post- tensioned brickwork beams. A total of 51 full -scale beams were tested. The following variables were considered:

(i) brick strength, (ii) mortar grade, (iii) steel area and prestress force, (iv) shear span /effective depth ratio.

The effect of these variables on the deflection, cracking and ultimate load were studied. A comprehensive series of small specimen tests were also undertaken to determine the material properties of the brickwork. A computer programme was developed to predict the flexural behaviour of the beams, using the non -linear stress /strain relationship of brickwork obtained from the small specimen tests and taking tension -stiffening into account. The theoretical method was then compared with the experimental results. An expression for predicting the average crack width in the beams was also developed.

A limited investigation into the shear strength of post -tensioned brickwork beams was carried out, the variables studied being the shear span /effective depth ratio, % of steel and the influence of shear reinforcement. It is shown that the plastic method for predicting the shear strength of prestressed concrete beams can be applied to prestressed brickwork beams.