Seismic Strengthening of Beam-Column Joints Using Diagonal Steel Bars

Abstract

It is known that beam-column connections are subjected to high stresses during earthquakes. Therefore, the design of these connections plays an important role for an earthquake resistant structure. Closely spaced stirrups should be used in beam-column connections to carry these stresses safely. Since the placement of ties required by the code in this region is rather difficult, this condition is ignored in many cases. Consequently, beam-column joints are sometimes deficient in terms of seismic behavior. In a beam-column connection which has no sufficient shear reinforcement, it is suggested that additional reinforcement arranged by placing steel bars into diagonal holes drilled from the outside and anchoring them by epoxy can carry principal tensile stresses in beam-column connections. This experimental study was carried out at the METU Structural Mechanics Laboratory by using T-shaped test specimens reflecting an exterior joint region of a frame having usual dimensions reduced to a scale of approximately 2/3. Total of eleven specimens were tested, where four were reference specimens and remaining seven were strengthened at the joint region with diagonal steel bars