NEESR: Seismic Performance of Conventional and Innovative Special Structural Walls

The project explored design and performance limits for structural walls, considering both conventional wall construction practices and innovative construction practices. A principal finding of recent earthquakes (in 2010 and 2011) and laboratory tests from 200 to 2010 is that wall performance is limited by stability and ductility capacity of the flexural compression zone. Given this critical issue, a series of studies on conventional walls and boundary elements constructed with innovative materials (HPFRCC) to establish performance limits for flexural compression failures in reinforced concrete structural walls. Tests were designed to acquire knowledge, improve construction practices, and advance simulation tools. The primary research outcomes include:

(1) Completing tests of eight ordinary boundary element (OBE) prisms at UCLA. The test specimens were detailed according to ACI 318-11 21.9.6.5 with the goal of assessing failure modes and strain capacities as influenced by concrete cover, configuration of transverse reinforcement, and spacing of transverse reinforcement. Based on the tests, a relationship used to assess buckling of longitudinal reinforcement was extended to wall boundaries with typical OBE detailing.
(2) Completing tests on 13 special boundary element (SBE) prisms at UC Berkeley. The tests investigated the role of boundary element detailing and wall thickness. The tests indicated that the strain capacity of relatively (< 12 inches) walls with ACI 318 code compliant SBE detailing was less than one percent and that improved detailing or high-performance, fiber-reinforced concrete did not improve the strain capacity significantly.
(3) Conducted tests on seven, approximately one-half scale wall panels represented the base of roughly 8 to 10 story walls in a moderately tall building. The primary test variables were the configuration and quantity of boundary transverse reinforcement, the depth of the neutral axis, and the wall thickness. The test provided essential data to develop a new, displacement-based model for predicting the drift capacity of structural walls with SBE.
(4) Developing code change proposals that were approved for ACI 318-14 and additional code change proposals that have been approved for inclusion in ACI 318-19.
(5) Creating and documenting a detailed dataset that was uploaded to DesignSafe-ci Data Depot that can be used for future reserarch.