Seismic design of low-rise buildings based on frequent earthquake response spectrum

Special provisions for the design of concrete frame structures to fulfill the immediate occupancy performance level for frequent (or low magnitude, or service) earthquakes are unavailable, or it is believed that drift control assures this compliance. This paper evaluates a different procedure for the structural design that guarantees an appropriate behavior for frequent (or service) earthquakes and for rare (or design) earthquakes, limited to short period concrete frame structures up to two stories. A two-story building with the typical architecture of a school is proposed as the study case. In order to compare the design procedure behavior, special moment frame (SMF) and intermediate moment frame (IMF) designs have been developed, as ASCE/SEI 7-16 and ACI 318-14 suggests in the regulations that the Ecuadorian code (NEC-2015) presents. An additional building is designed with the proposed procedure, for an earthquake with a return period of 43 years. To evaluate the behavior of the proposed structures, FEMA P-695 recommendations were followed, and non-linear models were developed using pushover and lime history analyses. Results show for the buildings that were designed with the current regulations excessive demands in the non-structural elements expected for the frequent earthquake and that the proposed design methodology satisfies the behavior levels required by the regulations, without producing an abrupt change in the existing design procedure.