Discipline: Technology and Engineering
Subcategory: Civil/Mechanical/Manufacturing Engineering
Room: Virginia C
Jeriann M. Ocasio Espinosa - University of Puerto Rico at Mayaguez
Co-Author(s): José R.Arroyo Caraballo,University of Puerto Rico at Mayagüez, Puerto Rico
The island of Puerto Rico is in the boundary of the Caribbean tectonic plate. Topography and socio-economic situation existing in Puerto Rico provide the conditions to have many residential structures built on hills by using slender high gravity columns. The vulnerability analysis of these structures based on the Capacity Spectrum Method made by Vázquez in 2002, concluded that most of the models could withstand earthquakes. Vázquez proposed a retrofit technique using Reinforced Concrete (R/C) walls. However, in this research project, the behavior of these structures retrofitted with the Steel Cross Bracing Unit (SCBU) was studied. The SCBU is the main single unit of a structural system, which consists of a steel element unit with a “X” shape and is about the size of a concrete block but with 1/3 of the concrete block weight. The objective of this research were to analyze two residential structural frames with and without the SCBU using the Capacity Spectrum Method based on ATC 40 (1996) and compare the SCBU retrofit technique against the use of R/C walls technique. Also, performed a cost estimated to check the viability of the SCBU retrofit technique. However, for the frame modeling in SAP2000, two frames were analyzed composed by two stories and two spans. Every property of these frames were applied following the specifications on Vázquez thesis. Otherwise, for the cost viable analysis, would be needed the cost of the SCBU with their connection and the erection cost. Therefore, for the fabrication cost a welder made the estimation and for erection cost of the SCBU wall and R/C wall a contractor made it. In addition, the added weight that each technique adds to the structure was compared. Finally, the results of the residentials frame analysis demonstrated the SCBU can increase the stiffness of the structure and reduce the lateral displacement of both frames, even using just one wall of the SCBU. The SCBU reduces the weight added of the structure, having 82% less weight than the R/C wall. Otherwise, it must be analyzed the SCBU cost based on mass production in an industrial process which compare with the concrete block production cost. However, in future researches a simplification of this mathematical model must be made for engineering practice, modeling the SCBU wall as a single diagonal spring between columns. Also, additional research must be done in relation to the thermal conductivity and noise propagation across the SCBU wall system covered with Plycem or gypsum board. References: Vázquez Torres, Drianfel E. (2002). Seismic behavior and retrofitting of hillside and hilly terrain reinforced concrete houses raised on gravity columns. (pp.1-94, Tech.) Ocasio Espinosa, J. M., & Arroyo Caraballo, J. R. (2017). Improving Lateral Stiffness of Reinforced Concrete Frames Using Multiple Steel Cross Bracing Units (pp. 1-24, Tech.). ATC 40, (1996). Seismic Evaluation and Retrofit of Concrete Buildings, Applied Technology Council, California Seismic Safety Commission.
Funder Acknowledgement(s): I thank Jose R. Arroyo for helping as advisor and being an excellent professor. I also thank PRLSAMP for funding and supporting this project.
Faculty Advisor: Jose R. Arroyo Caraballo, firstname.lastname@example.org
Role: Frame modeling of the structures retrofitted with SCBU in SAP2000 program, the cost estimation and the comparison of the added weight that each technique adds to the structure.