This Week's Featured Presentation
Performance-Based Seismic Design of RC Buildings: State of Practice (ACI Fall 2017 Convention, Anaheim, CA)
Recent advances to both the body of knowledge and the computing power available to structural engineers have created opportunities for tall buildings to be designed and analyzed with a better understanding of the structure’s seismic response than ever before. This has ushered in a new age of efficient tall buildings designed using a performance-based design (PBD) philosophy. This presentation will discuss in detail case studies of tall building projects, under construction or completed on the West Coast that utilized performance-based design principles and nonlinear modeling. Each project will be used to highlight a unique aspect of the design process and give the audience a glimpse into what is possible using state-of-the-art seismic analyses and underline emerging topics. Design of slender shear wall cores and eccentric cores will be addressed. Comparative studies showing the difference in geometry and reinforcement using code-prescribed procedures and performance-based methodologies will be presented. The mechanism of seismic energy dissipation through ductility will be illustrated. Ductile core approach can result in smaller cores with less overall force in the system, creating value through material and labor savings. Additionally, special attention will be given on how recent research on high-performance fiber reinforced concrete (HPFRC) has been incorporated into the design of tall buildings through the use of performance-based approach and nonlinear modeling. In addition, the practical implementation of these innovative designs will be discussed from a constructability perspective. Parametric studies of various modeling assumptions will be presented to show the importance and sensitivity of each selection. One of the key goals of this presentation is to increase awareness of the importance of PBD and ductility in the design of tall buildings in high seismic regions.
July 22 – 28
Testing and Analysis of Precast Concrete Wall Panels
by Marlon Bazan, Protection Engineering Consultants; and Charles Oswald, Protection Engineering Consultants
Blast Resistance of Precast Concrete (ACI Fall 2018 Convention, Las Vegas, NV)
This paper presents and discusses results from arena blast tests and shock tube tests on non-load bearing precast concrete wall panels and compares observed dynamic response and damage against single-degree-of-freedom (SDOF) analysis results. The tests include single-span panels and two-span continuous panels with conventional and prestressed reinforcement, and include both solid and insulated (“sandwich”) precast panels. The measured dynamic deflections and reactions are compared to the corresponding values calculated with SDOF analysis method commonly used for blast resistant design. Also, the observed panel damage levels at measured levels of response are compared to current response criteria for reinforced concrete panels. These comparisons are used to evaluate the accuracy and adequacy of the simplified SDOF methodology and the degree of conservatism in the current response limits for blast design of precast concrete wall panels. The current and proposed methodology for modeling the rebound response of concrete walls panels and the amount of composite action for sandwich panels in SDOF analysis are evaluated. The results from this study can be used to evaluate and update current guidelines for blast-resistant design of precast concrete wall panels.