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CUREE-Caltech Woodframe Project

Element 1 - Testing & Analysis
Task 1.4.8.1 – Nail and Screw Fastener Connections

PI: Fernando S. Fonseca (Brigham Young University)

Main Objectives

The objective of the research is to establish a database for sheathing-to-wood connections from which parameters necessary for modeling purposes can be extracted.

Methodology

A simplified testing apparatus has been designed and built for the testing of the connections and is shown below.

The database will be established using the results from the coupon tests of this research project. The database will be used to describe sheathing-to-wood connections and to define default parameters of a modified hysteretic model. CASHEW – A Computer Program for Cyclic Analysis of Wood Shear Walls has been developed for the practicing user.

The modified model uses a monotonic envelope curve as the backbone and a hysteretic rule-based model to describe unloading and loading characteristics. The main parameters describing the backbone curve are the initial stiffness, the secondary or post-yield stiffness, the load at which the post-yield stiffness intersects the load axis (load corresponding to zero slip), and the maximum deflection, which defines the maximum load and the starting of the descending branch. The modified model takes advantage of hysteretic rules to describe unloading and loading possibilities. The main parameters describing the hysteretic model are the unloading stiffness, the slip load, the slipping stiffness, and the reloading stiffness, which is defined by the previous maximum unloading point.

Photos:

Photo of the two types of coupons used for this test.
Testing Jig: The testing apparatus running the test.
Graph of the load-slip curve of the real data vs. the load-slip data from Hyster.

More Information

    CUREE Report : W-16: Nail, Wood Screw, and Staple Fastener Connections

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last updated 09.26.11