Experimental investigation of slitted web steel moment resisting frame

Abstract

This paper presents the results of three tests to evaluate cyclic behavior of Special Moment Resisting Frames (SMRF) with Slitted web section (SW-MRF). Typically, in SMRFs energy is dissipated by formation of plastic hinges at the beam ends. Nevertheless, based on the recent seismic codes, the span-to-depth ratio of beams in SMRFs should be larger than a minimum value to assure the development of plastic hinges with sufficient length at beam ends, reducing application of short span beams. In this paper, a new approach is proposed for short and medium span beams to transmit the flexural plastic hinges from the beam ends to the beam center by slitting a portion of the beam web at the mid-span and formation of a shear link. The idea can be applied for design of new buildings and for the purpose of rehabilitation in the damaged SMRFs. Two single-bay one-story SW-MRFs are constructed and tested under the quasi-static cyclic loading. One test was conducted on a new frame and the other test on an already flexurally damaged frame. This paper describes the specimen design, construction, experimental setup and results of the test. The test results are compared with the corresponding MRF specimen with a similar geometry and material properties. The results indicate that the proposed idea provides a stiff and ductile system via stable hysteretic loops, which makes it a suitable option for the design of new buildings and retrofit of damaged moment resisting frames.