Experimental Study on Lateral Strength Evaluation of Unreinforced Masonry-Infilled RC Frame

Abstract

In this study, RC frames with unreinforced masonry (URM) infill for typical school buildings in Korea are experimentally investigated to evaluate their seismic performance. For this purpose, one-bay, one-fourth scale specimens, with unreinforced concrete block (CB) infill having different boundary conditions due to beam rigidity, are tested under in-plane cyclic loading, using a distinctive measurement scheme consisting of three-axis strain gauges attached to all CB units. In this paper, the diagonal strut mechanism of CB infill including its main strut angle, average compressive strain, and equivalent strut width is discussed using principal compressive strains on CB units. The lateral strength carried by CB infill and RC frame from the overall response of the specimens is also explained, based on the compressive stress acting on the infill and the curvature distribution along RC members during the test.

Seismic Capacity of Rc Frame Buildings With Masonry Infill Damaged by Past Earthquakes

“…It should be noted that several assumptions have been made for the calculations as noted before, such as in-plane failure precedes the out of plane failure based on damage reported in literature [6][7][8]. However, this is not a general rule, and should be taken with precautions especially with masonry infill with gaps around the frames, large openings and masonry walls without bounding frame.…”

“…This paper briefly discusses the results of past experimental studies in order to understand the parameters influencing the shear strength of masonry infill. Figure 3 shows the relation between the shear strength of the masonry infill and the masonry prism compressive strength, fm, based on a database of experimental results from nine different researchers [6][7][8][9][10][11][12][13][14] and details of the experimental results are summarized in [15]. The database consists of single-story, single-span RC frames with masonry infill tested under static cyclic loading with several types of masonry bricks.…”

“…This paper briefly discuss the results related to deformation limits for masonry infill based on database of experimental studies [6][7][8][9][10][11][12][13][14], that are summarized in [15]. Rmax and Ru, represent the story drift at maximum strength and story drift when the lateral strength degraded to 80% of maximum lateral strength, respectively.…”

Modeling of interactions between RC columns and masonry infill in buildings with a column‐sway mechanism

“…The thickness and material properties of the strut were identical to those of the infill. The strut width was defined based on the column‐infill contact length because the strut was likely to reach the strength at the column‐infill boundary under higher compression, and this is supported by a recent experimental research that indicates higher compressive stress at the ends of the strut . As shown in the figure, the proposed model evaluates the column‐infill contact length by assuming ideal flexural/shear deformation of the column/infill.…”

“…In addition, the proposed model was applied to several brick masonry infilled RC frames in Indonesia, and the results indicated good agreement . However, further studies are required to investigate the applicability of the proposed model with respect to infills with different failure modes and for multi‐span moment‐resisting frames or weak beam‐strong column type frames …”