David Mar is a Partner at Mar Structural Design. His work emphasizes innovation and craft, synthesizing creative engineering and applied research. He has extensive experience in the field of Performance-based Design, having designed numerous rocking wall systems and rocking frame systems. In the area of applied research, he was project technical director of FEMA P807, Guidelines for Seismic Retrofit of Weak-Story Wood-Framed Buildings. He is also a member of the Project Technical Committee of ATC 138-5, the team creating the Methodology for Assessment of Functional Recovery Time, and update of the performance assessment methodology in FEMA P-58. David is the chair of the BSSC Provisional Update Committee’s Issue Team 13, whose goal is to Nurture Creativity and Innovation in Seismic Design. David graduated from UC Berkeley with a BS and MS in Structural Engineering and has practiced for thirty-five years.
This presentation was developed as a webinar on performance-based design, commissioned by ACT and FEMA. It introduces the concepts of performance-based design (PBD) in three sections, and within the framework of real projects. The first section provides context – defining performance-based design as a means for engineers to exercise design choices beyond the limitation of prescriptive code design. With PBD, engineers can design what they want, design what is needed, and design what the project can afford. Structural and non-structural damage are shown to be the drivers of seismic resilience and economic losses (FEMA-P58). Five core design principles are presented as essential elements for a designer’s undertaking of PBD. They are the requirements to (1) establish a lateral system’s mechanism utilizing capacity-based design principles, (2) determine a lateral system's strength and displacement capacity, (3) ensure gravity system compatibility, (4) design the foundation response, and (5) understand drift limits as they affect the architectural elements. Three example projects will highlight the principles. The first is a low-cost seismic retrofit to improve life-safety against collapse. The second is a high-value seismic design that uses PBD to obtain the best performance possible with a cost-neutral design. The third example is a low-damage and resilient design that uses PBD to achieve exceptional structural performance as well as limit damage to architectural systems.