It is common knowledge by now that very major changes in the design and detailing requirements for special shear walls was made in ACI 318-19, which goes into effect in California on January 1, 2023. Among the most important of the changes from ACI 318-14 are the following: 1. Shear amplification - design shear (required shear strength) Vu of ACI 318-14 is required to be amplified by a factor of up to 3 (similar to New Zealand, Canada). 2. Improved wall boundary and wall web detailing – required are overlapping hoops if the boundary zone dimensions exceed 2:1, crossties with 135-135 degree hooks on both ends, and 135-135 degree crossties on web vertical bars. 3. Check on mean top-of-wall drift capacity at 20% loss of lateral strength - a low probability of lateral strength loss at MCE-level hazard is required, and 4. Minimum wall boundary longitudinal reinforcement – this is required to limit the potential of brittle tension failures for walls that are lightly reinforced. Severe restrictions on lap splice locations. In a presentation before the Los Angeles Tall Buildings Structural Design Council, Wallace et al. concluded: ACI 318-19 increased the shear demand by a large factor to consider capacity-based design; however, it did not provide any increase on the capacity side … . Use of shear walls for mid-rise buildings will not be feasible. Moment frames will be the only alternative.” A near-consensus has now emerged that adjustments to some of the ACI 318-19 changes are badly needed. The proposed presentation discusses a number of these needed adjustments.
Dr. S. K. Ghosh is known internationally for his work in earthquake engineering. He has influenced seismic design provisions in the United States for many years by serving on or chairing numerous committees and advisory panels. He specializes in the analysis and design, including wind and earthquake resistant design, of reinforced and prestressed concrete structures. Dr. Ghosh is active on many national technical committees and is a fellow of ASCE, SEI, ACI, and PCI. He is a member of ACI Committee 318, Standard Building Code, and the ASCE 7 Standard Committee (Minimum Design Loads for Buildings and Other Structures). He is a former member of the Boards of Direction of the Building Seismic Safety Council (BSSC), the American Concrete Institute (ACI), and the Earthquake Engineering Research Institute (EERI).
More Information
Speakers
S. K. Ghosh, PH.D.
Duration
150.00 mins
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