Behavior of External Reinforced Concrete Beam to Column Connections Subjected to Earthquake Type Loading.

Abstract

Twelve full-size exterior reinforced concrete beam to column connections were tested to obtain sufficient data which would justify a simplification of the existing design guidelines. The column portions of the specimens were first subjected to a constant axial load. The specimens were then subjected to a displacement controlled loading history to simulate the type of displacements a connection may experience during a severe earthquake. The effect of four primary variables on the overall performanceof the connections were studied. The flexural strength ratio, definedas the ratio of the sum of the flexural strengths of the columns tothat of the beam, was varied between 1.1 and 2.0. The amount oftransverse reinforcement in the joint was varied between 1.0 percent and 1.5 percent. The level of the joint shear stress ranged between10SQRT.(f(,c)' (psi units) and 14SQRT.(f(,c)'. On half of the specimens tested,(' )transverse beams and slabs were added to investigate the effect ofthe additional confinement provided by these elements. Experimental results from these tests indicate that in many cases, a lower amount of transverse reinforcement than that recommended by ASCE-ACI Committee 352 may be used without jeopardizing the overall behavior of the connection. The results of these tests were incorporated with results from beam to column connections tested by other researchers to develop a simple design chart. Knowing the flexural strength ratio and the shear stress level at a joint, the design chart will indicate the required percentage of transverse reinforcement for the joint. The design chart requires that the flexural strength ratio be greater than or equal to 1.4 for exterior connections.