Experimental testing of a rocking timber shear wall with slip‐friction connectors

Abstract

SUMMARY Allowing a structure to uplift and rock during an earthquake is one way in which activated forces can be capped and damage to the structure avoided or minimised. Slip‐friction connectors (also known as slotted‐bolt connectors) were originally developed for use in steel construction, but for this research have been adapted for use as hold‐downs in an experimental 2.4 m × 2.4 m rigid timber shear wall. A novel approach is used to achieve the desired sliding threshold in the connectors, and the wall uplifts when this threshold is reached. From a series of quasi‐static cyclic tests, it is shown that slip‐friction connectors can impart ductile and elasto‐plastic characteristics to what would otherwise be essentially brittle structures. Because forces on the wall were capped by the slip‐friction connectors to levels well below the design level, no damage to the wall was observed. Self‐centring potential was also found to be excellent. The slip‐friction connectors themselves are of a unique design and have proven to be robust and durable, adequately performing their duty even after almost 14 m of cumulative travel under high contact pressures. To resist base shear without unduly affecting rocking behaviour, a new type of shear‐key is proposed and implemented, and a procedure developed to quantify its influence on overall wall behaviour. Copyright © 2014 John Wiley & Sons, Ltd.

A low damage and ductile rocking timber wall with passive energy dissipation devices

“…The experiments sketched in Fig. 4 are reported in detail by Loo et al (2014b), and the reader is referred to that article for a comprehensive account of the experiments. The 2.44 m×2.44 m wall was fabricated from two panels, each 1.22 m wide by 2.44 m high.…”

“…An expression was then derived by Loo et al (2014b) where n parallel is the number of washers in parallel, n series the number in series, t the thickness of a single washer, P flat the force required to deflect a single washer to the flat position, and δ flat the distance to the flat position of a washer. Accuracy in setting the preload in the tension bolts will naturally mean that any difference between the strengths of the two connectors at opposite ends of the wall is minimized.…”

“…Accuracy in setting the preload in the tension bolts will naturally mean that any difference between the strengths of the two connectors at opposite ends of the wall is minimized. This is important because Loo et al (2014b) demonstrates that only where the difference in strength between the two connectors is less than the total gravity loading on the wall will the wall be capable of descending at one end, while uplifting at the other -a capability without which re-centring would not be possible…”

“…4(c) for variable definitions) were derived. For moment resistance, Loo et al (2014b) provides the following expression…”

“…K mrp encapsulates the influence of the shear key, and is a function of its geometry and the coefficient of friction between the shear pin and shear plate (refer to Loo et al (2014b) for the derivation)…”