Nonlinear behavior of code-designed reinforced concrete concentric braced frames under lateral loading

In this paper the authors summarize the results of a study devoted to evaluate, using static nonlinear analyses, the behavior of low to medium rise ductile moment-resisting reinforced concrete concentric braced frame structures (RC-MRCBFs) using chevron steel bracing. RC-MRCBFs were assumed to be located in soft soil conditions in Mexico City and were designed using a capacity design methodology adapted to the general requirements of the seismic, reinforced concrete and steel guidelines of Mexico’s Federal District Code (MFDC-04). From the results obtained in this study it is possible to conclude that the capacity design methodology used by the authors is successful to design low and medium rise ductile RC-MRCBFs when the columns of the moment frames resist at least 50% of the total seismic shear force, supporting with numerical evidence the proposed strength balance established in MFDC-04. However, there is a need to improve current guidelines in MFDC-04 in order to warrant ductile behavior for this structural system and to attain the expected collapse mechanism of a strong column-weak beam-weaker brace, especially for slender buildings, a task that requires further research studies.