Analysis of Partially Grouted Masonry Shear Walls.
Analysis of Partially Grouted Masonry Shear Walls.
(2534 K)
Shing, P. B.; Cao, L.
NIST GCR 97-710; 45 p. March 1997.
Sponsor:
National Institute of Standards and Technology,
Gaithersburg, MD
Available from:
National Technical Information Service
Order number: PB97-153987
Keywords:
masonry; walls; mortar joints; reinforcing bars;
sensitivity analysis
Abstract:
Six partially grouted reinforced masonry shear walls
that were tested at NIST are analyzed in this study.
The main aim of the study is to assess the capability of
some state-of-the-art finite element models in
predicting the behavior of these wall specimens under
cyclic in-plane lateral loads. To this end, two types
of elements are used to model the behavior of a
partially grouted masonry wall to reflect the
inhomogeneity and anisotropy introduced by mortar
joints. The shear and tensile behavior of a mortar
joint is modeled with plasticity-based interface
elements, while the fracture behavior of masonry units
is modeled with smeared crack elements. The analyses
have been carried out in several stages. First, a
pretest analysis was conducted on one of the wall
specimens. This was followed by an extensive parametric
study to identify the sensitivity of numerical results
to the modeling parameters. Finally, the finite element
models have been fined tuned with data obtained from
relevant material tests that were conducted in
conjunction with the tests of the wall specimens. The
main variables in the wall specimens are the aspect
ratio of the walls and the quantity of horizontal
reinforcement. It has been shown that the behavior of a
partially grouted reinforced masonry wall is very
similar to that of a reinforced concrete infilled frame.
The grouted masonry provides the frame action while the
ungrouted masonry acts like infill panels. The
numerical results show that the quantity of the
horizontal steel in the bond beam has little influence
on the behavior of the wall specimens. The walls with a
low aspect ratio tend to exhibit a distinct sliding
shear failure through the bed joints at mid-height,
while those with a higher aspect ratio have more severe
cracking in the vertical joints within the wall panels.
The vertical cracks between the grouted and ungrouted
cells are reasonably well captured in the analyses.
However, except for one wall specimen, the lateral
strengths obtained in the analyses are higher than those
shown by the experiments. The discrepancies in the
numerical and experimental load-displacement curves can
be partly caused by the different load histories and
partly by the discrepancy in the bond strength between
the wall panels and the concrete head beams.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899