Factors Affecting the Strength of Blockwork Walls Subjected to Transverse Horizontal Loading

Codes of Practice and previous research concerned with the transverse lateral strength of unreinforced masonry walls is reviewed with particular reference being made to flexural strength and stiffness, shear bond, tensile bond, moisture movements and arching action.
A programme of tests to investigate the flexural strength and stiffness, shear bond strength and tensile bond strength of three distinct types of blockwork masonry is described.
Methods of analysing vertical spanning walls are compared and a theory based upon the stability of cracked walls is proposed.
Factors affecting the tensile bond are discussed with reference to the results of more than 300 couplet tests which were carried out with three concrete block types, three moisture conditions and six mortars. Strain measurements taken across the joints in some of the couplets to determine the distribution of strain are described and methods of analysing the stresses are proposed.
Measurements of moisture movements taken an a variety of test walls are presented and analysed and a hypothesis to account for a thickness factor which became apparent in the test programme is proposed.
A series of arching tests is described and the results compared with predictions based on theories for uncracked and cracked walls developed as part of this research programme.
The strengths of certain full sized test walls are compared with ultimate strengths calculated by various design methods. The strengths determined in accordance with the British Standard Draft Code of Practice fer Unreinforced Masonry are shown to be conservative.
The thesis concludes with an Appendix which gives details of some preliminary investigations into the compressive strength of masonry specimens.