Experimental performance of RC moment frame beams with rectangular openings: Fid-Bau Portal

Experimental performance of RC moment frame beams with rectangular openings

Herrera, L. / Anacleto-Lupianez, S. / Lemnitzer, A.

Highlights•An experimental case study of moment resisting frame beams with openings is presented.•Large scale beam specimens are subjected and analyzed under reverse cyclic loading.•Nonlinear behavior, failure progression and plastic hinge development is compared with analytical predictions.•Contributions of shear and flexural deformations are evaluated using external instrumentation.•Monotonic strut and tie modeling was used to compare the elastic beam behavior up to yielding.

AbstractA large-scale experimental case study was carried out to investigate the cyclic behavior of T-shaped, moment-resisting frame (MRF) beams with openings. The beams are located in an existing structure in the western U.S., which was designed according to ACI 31-95 and UBC97. Limited availability of test data in current literature and lack of guidance in existing design standards motivated the construction of four replica cantilever test specimens with lengths of 3.8–5.3m. All other specimen dimensions were scaled to 80%, resulting in cross-sections of 0.61 in width and 0.98m in height. Three beam specimens had openings with dimensions of 0.98m×0.37m; the control specimen did not have openings. Each beam replica was instrumented with internal and external instrumentation consisting of strain gauges, linear voltage differential transducers (LVDTs) and string potentiometers, and tested to complete structural failure under quasi-static symmetric displacement reversals. The cyclic performance of all beams was evaluated in terms of failure progression and plastic hinge development, strength and stiffness degradation, and energy dissipation capacity. In addition, the contribution of shear and flexural deformations to the overall displacement profile was studied. Simple monotonic strut and tie modeling was utilized to estimate and compare the beams’ capacities in the elastic range. A discussion of deficient and successful test results highlights the suitability of introducing openings in moment frame beams.