Abstract:
The composite action between masonry wall and its supporting beam
concentrates the vertical loading applied on the top of wall close to the beam supports.
This produces bending moments much less than would be expected when the full load
is acting directly on the beam. The study of this composite action is of economic
importance since if the concept is utilised, a rational design of the beam will be
achieved.
This thesis presents a comprehensive material model and its incorporation into
non-linear finite element computer model for the analysis of wall-beam structures
made with brickwork of solid brick subjected to uniformly distributed load. The
program is incremental in nature and capable of reproducing the non-linear behaviour
caused by material non-linearity and progressive local cracking and crushing. The
program is thus capable of modelling the behaviour of wall-beam structures subjected
to non-linear load from first crack to final failure. The material model used in this
program is derived from tests on representative samples of brick, mortar and small
samples of brickwork.
In the finite element model brick, mortar, concrete and steel are treated as
separate materials along with the simulation of actual directional effects of mortar
joints. A series of failure criteria have been adopted to model the different modes of
failure experienced in the constituent materials. Due to the crack sensitive nature of
the problem, particular emphasis has been given to the modelling of cracking and the
post-cracking behaviour of the materials, especially the manner in which the local
stresses in the fractured region are redistributed.
The results of finite element model have been verified by comparison with
experiments on brick masonry wall-beam structures subjected to uniformly distributed
load applied at the top and extending over the full length and thickness of the wall.
Comparison with published literature reveals that the present method can provide a
more comprehensive prediction of behaviour of the wall-beam structure up to failure
load.
Sensitivity analyses of the various parameters defining the material model and
the boundary conditions have been carried out. With the important parameters thus
obtained, the finite element model has been used to carry out a comprehensive
parametric study of the behaviour of storey height wall-beams subjected to uniformly
distributed load. Based on the findings of this study, design recommendations have
been proposed. As the computer program developed can handle general cases with
arbitrary geometry, loading and boundary conditions, recommendations for
investigations of various other wall-beam structures have been made.
