Seismic retrofit of flat-slab buildings with masonry infills

Lateral drift of order flat-slab buildings subjected to seismic loading can be controlled by appropriately placing and mobilizing masonry infills. The modeling of infills as equivalent diagonal compression struts is examined. Finite elements analysis is used to identify the parameters having most effect on infill-frame interaction under lateral loading. An equivalent effective width of the diagonal strut is proposed for masonry infill panels with and without openings for use in lateral load analysis of reinforced concrete flat-slab frames (AU)

Hysteresis model for seismic analysis of non.ductile flat - plate buildings

Recent awareness of the probability of a moderate seismic event east of the rockies has caused concern of the damage potential of the existing stock of ordel flat-slab buildings which were designed to resist gravity load only. In an effort to evaluate the seismic resistance of non-ductile flat plate buildings, an experimental study was conducted to characterize the inelastic hysteretic behavior of typical slab-column connections. Based on test observartions, a general hysteretic model of the slab-column connection was developed. Four control parameters were identified to characterize the hysteresis loops for typical interios and exterior connections respectively. The model was incorporate into an inelastic computer code for seismic analysis of reinforced concrete structures and used in analytical simulations of shear-drift response of single connections. The suitability of the proposed model for evaluatiing the seismic performance of flat-plate buildings is discussed (AU)

Seismic resistance of slab - column connections in existing non-ductile flat-plate buildings

An experimental investigation was conducted to evaluate the seismic resistance of slab-column connections in existing non-ductile flat-plate buildings. The test subassemblies were designed and detailed in accordance with the building codes of the late forties and fifties. each subassembly consisted of two exterior and one interior connection and was subjected to several cycles of increasing lateral displacements. The test variables included the slab reinforcing detail, intensity of the gravity load applied to the slab, and the presence of a spandrel beam. Rapid stiffness degradation, significant reduction in deformation capacity under increased gravity load, and limited moment-transfer capacity of connections were observed to be the main response characteristics of the non-ductile slab-column connections subjected to earthquake-type loading. The connections were able to sustain full design dead and live loads through at least 2 per cent drift. However, 70 per cent of the initial lateral stiffness of the connections was lost by this drift level. Under normal service loads, the connections were able to maintain at least 80 per cent of their strenght through approximately 4 per cent lateral drift and the transfer of unbalanced moment occured mainly on the column face with slab under negative bending(AU)