CUREE-Caltech Woodframe Project
Element 1 - Testing & Analysis
Task 1.3.1: Loading Protocol and Rate of Loading Effects
PI: Chia-Ming Uang (UC San Diego)
Evaluation of the performance of woodframed shearwalls has traditionally been based on quasi-static testing with no reversed loading cycles. More recently, researches have been performing cyclic testing in order to determine the effects of fully reversed loads analogous to the demand imposed by an earthquake. There exists however, no widely accepted standard protocol for the cyclic loading of woodframed shearwalls. The use of different protocols by researchers makes it difficult to compare results and frequently results in different failure mechanisms. In addition, very little is known about the effect of loading rate on shearwall performance.
Static and dynamic tests on woodframed shearwalls will be performed with the objective of a comparison of results given by the use of different protocols and loading rates. The CUREE-Caltech protocol developed under task 1.3.2 will be compared with other commonly used protocols such as the sequential phased displacement (SPD) protocol used in shearwall tests at the University of California, Irvine. Also of interest is an evaluation of the near-fault protocol developed in task 1.3.2 and a determination of the effects of loading rate.
Standard construction 8 ft ¥ 8 ft woodframe shearwalls with different panel configurations (both structural and nonstructural) are being tested using varying loading protocols, and loading rates. Framing, nailing and hardware configurations resemble those used in the full-scale shake table test performed under task 1.1.1. The loading protocols considered in the testing are the following:
The dynamic tests were performed using the CURE-Standard protocol at a period that increases from 0.3 to 0.7 seconds during the test. Primary elements under consideration are strength, stiffness, ductility, energy dissipation, and failure mechanism.