		2009 NZSEE Conference
	Abstracts

Keynote Address Session 1 Session 2 Session 3A Session 3B Session 4A Session 4B Session 5A Session 5B Session 6 Session 7 Poster Session

In-Plane Experimental Testing of Timber-Concrete Composite Floor Diaphragms

Michael Newcombe, D. Carradine, Stefano Pampanin, Andrew Buchanan, Bruce Deam, W.A. van Beerschoten and Massimo Fragiacomo

Recent advances in the design of multi-storey timber buildings have led to viable structural systems that allow open floor plans with large spans between frames and/or walls. Timber-concrete composite (TCC) flooring can achieve the spans required but have the potential to be flexible under diaphragm actions, which can significantly alter the seismic response of a building.

In-plane experimental tests on a one-third scale TCC floor were performed using quasi-static earthquake loading simulation. The experimental results indicate that the deformation between the floor and lateral load resisting systems (LLRS) is much greater than the in plane deformation of the floor diaphragm itself for the square aspect ratio considered. Hence, a floor system with similar aspect ratio can be modelled as a single-degree-of-freedom for future structural analyses.

Different diaphragm connections were considered between the floor unit and lateral restraints, which simulate the lateral load resisting system. The connection was either timber-to-timber or concrete-to-timber, incorporated screws or nails acting as dowels or inclined at 45 degrees. Each connection type performed differently in terms of stiffness, strength, ductility capacity and induced damage. Screws that were orientated at 45 degrees to the connection interface were significantly stiffer than fasteners aligned orthogonal to the interface. There was little difference in the initial stiffness for the concrete-to-timber connection compared to the timber-to-timber connection. The testing indicated that a timber-to-timber interface is more desirable because of construction ease and reparability.

Paper P19: [Read] [Presentation]

Dynamic Response of URM House Subjected to Forced Vibration

Abdul Razak Abdul Karim, Claudio Oyarzo-Vera, Norazzlina Sa'don and Jason Ingham

The results of non-destructive forced vibration tests on a small-scale unreinforced masonry (URM) house are presented. The main aim of the study was to assess the changes in system level response between the as-built and retrofitted structure. This includes assessment of diaphragm response, wall-diaphragm connection details, in-plane wall response, out-of-plane wall response, and the response of wall corners. Further, the test protocols were designed to investigate two types of retrofit techniques consisting of a plywood diaphragm retrofit and wall-diaphragm connection retrofit. However, this paper only presents the results of plywood retrofit as the experimental study is still in progress. From the results, it was found that the basic dynamic properties (natural frequency and mode shapes) and the force path of the as-built structure were significantly affected after applying the plywood retrofit.

Paper P20: [Read] [Presentation]

Seismic Performance of New Zealand Two-storey Brick Veneer Houses

Stuart Thurston and Graeme Beattie

Recent tests at BRANZ have shown that modern, clay-brick veneer single-storey houses perform well under seismic loading and the veneer can be relied upon to resist a significant portion of the seismic load. At lateral in-plane displacements well in excess of those expected in a design level earthquake the veneer settled back close to its original position on unload and cracks almost closed and could easily be repaired. Partial or full collapse did not occur even at very large lateral deflections. Tests by others have shown that modern clay brick veneer construction should perform well under out-of-plane earthquake loading.

This paper describes slow cyclic racking tests on a 6.7 m x 3.9 m plan two-storey homogeneous brick veneer house with window and door openings. Two-storey construction is currently not allowed by NZS 3604 and requires specific design. At design level displacements the veneer cracks mostly closed in a similar manner to the single-storey construction. The upper-storey veneer performed in a similar manner to a single-storey veneer but the lower-storey veneer was far stiffer. The veneer generally remained firmly attached to the timber framing even when the roof and first floor were displaced ±143 mm and ±69 mm respectively, although cracking at this stage was severe and did not completely close. Proposals to allow the veneer to provide a bracing function in NZS 3604 structures and to allow suitably proportioned two-storey brick veneer to be used without specific design will be submitted to Standards New Zealand.

Paper P21: [Read] [Presentation]

Evaluation of the Seismic Energy Demand For Asymmetric-Plan Buildings Subjected to Bi-Directional Ground Motions

Jui-Liang Lin and Keh-Chyuan Tsai

This paper proposes a method for the evaluation of the seismic energy demands of two-way asymmetric-plan buildings under bi-directional seismic ground motions. The proposed procedure conducts the modal response history analyses by using the three-degrees-of-freedom (3DOF) modal systems. This modal system represents the relationships of two roof translations versus two base shears and roof rotation versus base torque obtained from the modal pushover analyses. The proposed method is computationally efficient and conceptually clear, inherited from the advantages of the conventional modal response history analysis. The proposed procedure can be used to estimate the absorbed energies contributing from translational and rotational motions The study shows that the signs of modal eccentricity are a determinant for the plan-wise distribution of the modal absorbed energy. The accuracy of the proposed procedure was verified by analyzing the responses of one 3-storey and one 20-storey two-way asymmetric-plan buildings subjected to bi-directional earthquake excitations. These analytical results confirm the relationships between the signs of the modal eccentricity and the plan-wise distribution of the modal absorbed energy.

Paper P22: [Read] [Not Presented]

Floor Response Spectra for Ultimate and Serviceability Limit States of Earthquakes

S.R. Uma, John Zhao and Andrew King

Earthquake loading standards NZ 1170.5:2004 has introduced new provisions for the design of Non-Structural Components (NSC) and building parts taking into account of peak floor acceleration up the height of the building and spectral response of components. In this study, the acceleration demands on NSCs located in ductile lowrise and high-rise buildings of reinforced-concrete moment-resisting frames are analysed under earthquake records with two design levels representing life safety or ultimate limit state, and operational or serviceability limit state. The numerical results on the response of the components are derived using a floor response spectra approach. The floor response spectra up the height of the building have shown peaks near the modal periods which are not reflected by code provisions. This effect is observed both in SLS and ULS conditions, but more pronounced in SLS. Finally, the adequacy of the current provisions of NZS 1170.5:2004 in terms of acceleration demands for NSC with short and long periods have been verified.

Paper P23: [Read] [Presentation]

Keynote Address Session 1 Session 2 Session 3A Session 3B Session 4A Session 4B Session 5A Session 5B Session 6 Session 7 Poster Session