- Preliminary experimental verification of current content sliding modelling techniques
- T.Z. Yeow ; G.A. MacRae ; R.P. Dhakal ; B.A. Bradley
- Book Title / Journal: New Zealand Society for Earthquake Engineering (NZSEE) Annual Technical Conference
- Year: 2014 , Volume: , Series:
- Earthquake engineering
- Keywords: shake table testing ; friction coefficient
- Description
- Most analytical studies focusing on the sliding of building contents usually make an assumption that the friction force-sliding displacement behaviour is elasto-plastic (e.g. friction coefficient remains constant during sliding). This preliminary study uses experimental data to verify if this assumption is reasonable. Shake table tests of a desk on common flooring materials were conducted to investigate the factors influencing friction behaviour, and to observe the behaviour of the contents under sinusoidal motion. Up to a 15% decrease in friction coefficient was observed with either an 80% increase in mass or a 20 times decrease in relative velocity, indicating that the friction coefficient is dependent on these two parameters. A comparison of the experimental and analytical sliding response of the desk under a single sinusoidal loading pattern on carpet flooring was conducted. Results show that the displacement amplitude of a single sliding excursion and the general sliding trend is well approximated using the elasto-plastic assumption. As such, despite the dependence of friction coefficient on sliding mass and velocity, the elasto-plastic behaviour assumption appears to be reasonable for the sinusoidal loading pattern examined in this paper.
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- Shaking table tests of a base isolated structure with double concave friction pendulums
- F.C. Ponzo ; A. Di Cesare ; D. Nigro ; M. Simonetti ; G. Leccese
- Book Title / Journal: New Zealand Society for Earthquake Engineering (NZSEE) Annual Technical Conference
- Year: 2014 , Volume: , Series:
- Earthquake engineering
- Keywords: shake table testing ; Base Isolation ; SAP2000 ; friction pendulums
- Description
- An extensive experimental seismic testing programme named JETBIS project (Joint Experimental Testing of Base Isolation Systems) has been developed within the RELUIS II project (Task 2.3.2) involving partners from different Italian universities. This paper describes the shaking table test performed by research unit of University of
Basilicata (UNIBAS) on the experimental model with seismic isolators based on Double Concave Friction Pendulum (DCFP). The DCFP isolator contains two separate concave sliding surfaces and exhibits different hysteretic properties at different stages of
displacement response. The experimental model was a 1/3 scaled steel framed structure with one storey and one bay in both directions. Four DCFP bearings with equal properties of the concave sliding surfaces were mounted under each column. The base isolated experimental model was subjected to a set of 7+1 natural earthquakes increasing seismic
intensity in order to achieve the safe displacement of seismic bearings. The main objective of this work is to evaluate the DCFP effectiveness considering different experimental configurations (with both symmetrical and eccentric masses) and different
sliding surfaces conditions (with and without lubrication). A further goal is to verify the reliability of the DCFP isolation system when relevant residual displacements occur due to previous earthquakes. Finally, this paper also shows the experimental testing outcomes compared with the results of non linear time history numerical analyses using SAP2000.
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- Investigation of the behaviour of small-scale bridge models using shake table tests
- Z. Chegini ; A. Palermo
- Book Title / Journal: New Zealand Society for Earthquake Engineering (NZSEE) Annual Technical Conference
- Year: 2014 , Volume: , Series:
- Earthquake engineering
- Keywords: shake table testing ; Bridges ; skew angle
- Description
- The skew angle of a bridge is an important boundary condition that affects its behaviour under seismic loading. Although some research has been carried out to identify these effects, such investigations for the most part remain analytical with a few instances including experimental testing. In an effort to understand the effects of skew on the seismic behaviour of bridges, a number of shake table tests have been performed on a skew and a non-skew bridge model and the results have been compared. These smallscale models are representative of two-bay short-span concrete bridges and consist of
precast deck and pier elements which have been assembled using threaded bars. The results of the tests show that although the amount of deck rotation is not higher in the skew deck, this rotation is non-symmetric and may lead to unseating of the deck. It is also discussed that the results of these tests can be used in the design of ‘controlled rocking’ connections in precast bridge structures.
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