Concrete masonry infilled steel frames subjected to combined in-plane lateral and axial loading – An experimental study

• Masonry infilled steel frames were tested under combined lateral and axial loading.
• Behavior as affected by axial loads, grouting, and openings was discussed.
• Correlation between axial loads and the infill lateral resistance was examined.
• Efficacy of the Canadian and American masonry standards on infill design was assessed.

An experimental program involving the testing of 14 specimens was conducted to investigate the behavior and capacity of concrete masonry infills bounded by steel frames. Five infill specimens as well as one bare frame specimen were subjected to an in-plane lateral load applied at the frame top beam level whereas the remaining 8 specimens were tested under combined in-plane axial and lateral loading. Specimens included non-grouted, partially grouted and fully grouted infills. The openings of infills were also considered. The presence of axial load resulted in a marked increase in the lateral resistance of the infills and the correlation between axial load and lateral resistance is discussed. In addition, grouting and opening on the failure mode, lateral ultimate load, and stiffness of specimens are presented. The comparison of the test results with values suggested by the current design standards of both Canada and United States shows that the Canadian standard provides a markedly conservative design of masonry infills whereas the American design standard gives an improved estimate of infill stiffness and strength.