		2007 NZSEE Conference
	Abstracts

Keynote Address 1 Defining Acceptable Performance Criteria Planning for Expected Performance / Improving Existing Performance I Improving Existing Performance II Keynote Address 2 Developments Within Design I Developments Within Design II Developments Within Design III / Understanding the Inputs Assessing Existing Performance Poster Papers

Assessment of Seismic Performance of Structures by Health Monitoring

Oliver de Lautour and Piotr Omenzetter

The performance of existing structures can be assessed in real-time using Structural Health Monitoring (SHM). In this study, a SHM method is proposed and experimentally tested on a 3-storey laboratory structure mounted on a shake-table. Several damage conditions were simulated in the structure by a reduction in lateral stiffness. Typical stiffness reductions were between 7% - 10%. The structure was excited using a series of earthquake records. Examination of the acceleration time histories, using time series analysis and pattern recognition, enabled accurate detection, location and quantification of damage.

Paper P42: [Read]

Analytical Model on Beam Elongation within the Reinforced Concrete Plastic Hinges

Brian Peng, Rajesh Dhakal, Richard Fenwick, Athol Carr and Des Bull

Research in New Zealand over the last two and a half decades has shown that elongation in plastic hinge regions can have a very significant effect on the seismic performance of reinforced concrete buildings. It was found that elongation arises due to (i) plastic strain in reinforcing bars caused by inelastic rotation, and (ii) unrecoverable tensile strains in compression reinforcement. A number of empirical formulas have been proposed to predict elongation. However, there are currently no analytical models that can accurately predict elongation in the plastic hinges. Consequently, the influence of elongation on the seismic performance of reinforced concrete structures cannot be predicted analytically. This paper describes a plastic hinge model for the computer analysis package, ‘RUAUMOKO’, which can predict both the flexural and elongation response of plastic hinges in reinforced concrete beams. Experimental and analytical results are compared in the study. With the completion of this newly formed element, seismic analyses may be made of structures containing potential plastic hinges to assess the significance of elongation on seismic performance.

Paper P43: [Read]

Selection of Real Records for Scaling in Site Response Analyses

B. Yagci

In this study, site response variability was investigated under different series of ground motion records selected to region criteria and scaled by peak ground acceleration with respect to a pre-determined regional design earthquake. The analyses were carried out using SHAKE 91 for the nine soil profiles defined previously in Balikesir (Turkey). For determining the ground motion data series, the selection criteria were magnitude, distance and scaling factor for peak ground acceleration (the ratio of the target amplitude to the amplitude of the record being scaled) and two data series were compiled. In the first, records were downloaded from the PEER strong motion database that contains earthquakes in active tectonic regions but not from Turkey. In the other series, records were selected from earthquakes in Turkey. Response variability for each soil profile was investigated separately and together with acceleration spectrum with respect to the regionally different data series. For the specific case in this study, the scatter of response reduced for the series recorded in Turkey. For the other record series, significant response variability was observed.

Paper P44: [Read]

Overview of NZNEES@auckland

Quincy Ma, Piotr Omenzetter, Jason Ingham, John Butterworth and Mick Pender

Arising from the need for state-of-the-art facilities to conduct leading edge scientific research, and balancing the logistics of maintaining and operating such facilities, there is a global trend towards establishing networks of communal experimental and computational infrastructure. The New Zealand Network for Earthquake Engineering Simulation (NZNEES) represents such a network for earthquake engineering research in New Zealand. It is a network that takes advantage of the latest digital information technologies to overcome the obstacle of distance. It acts as a vehicle to interface with other similar networks overseas and permits New Zealand researchers to participate equally in the new global forum, collaborate with likeminded leading experts worldwide and access state-of-the-art resources and the global research funding pool. The NZNEES network is modelled on the U.S. NEES network and has the vision to further the human understanding of earthquakes through integrated experimentation, computation and simulation. NZNEES@Auckland, as the first active node on the NZNEES network, aims to provide a unique contribution to the global networks as a leader in forced vibration testing and monitoring of in-situ structural and geotechnical systems. This paper describes the current capabilities of the NZNEES@Auckland node through brief examples of recent research, tools, IT infrastructure and current collaborations.

Paper P46: [Read]

Lessons from the 2006 Asia Pacific IDEERS Seismic Design Competition

Aaron Wilson, Tom Algie, Rick Henry, Christopher Haigh and Quincy Ma

In 2006, a University of Auckland (UOA) team comprised of four undergraduate students participated at the 2006 APEC IDEERS seismic design competition in Taipei, Taiwan. The IDEERS competition is a competition that aims to promote interest in earthquake engineering research to university students and introduce the structural engineering profession to high school students. The competition challenges students to design and build the most efficient model of a multi-story building to withstand simulated earthquakes on a shaking table. In the months leading up to the competition, the UOA team built six practice models in order to optimise a design for the competition in Taiwan. Each of the models was tested on the UOA’s uniaxial shaking table. The final design of the model was a three storey structure designed using a strong column/weak beam philosophy.

In the competition, UOA competed against 35 other international teams in the undergraduate division and finished in fourth place. The UOA team found the IDEERS competition to be a very rewarding experience as it increased interest and understanding of earthquake engineering, provided practical implementation of technical theories learned in the classroom and was a great life experience to visit a truly foreign culture.

Paper P47: [Read]

Spatial Distribution of Strong Shaking Near the 2-D Source of Large Shallow New Zealand Earthquakes

David Dowrick and David Rhoades

This paper presents a widely applicable new attenuation model for predicting the spatial distribution of intensities in crustal earthquakes, derived using a two-dimensional source. The source is represented by a rectangular fault rupture plane of chosen dip, discretised into small rectangles each with its own share of the total seismic moment, and modelling chosen distributions of asperities. The spatial distributions are represented as isoseismals. Comparisons are made with the actual isoseismals of selected large historical New Zealand earthquakes and those predicted by the simpler models of Dowrick & Rhoades (2005a). Important differences and insights are found regarding spatial distributions of ground shaking within a few kilometres of shallow earthquakes with rupture length greater than about 25 km. The influence of asperities relative to that of non-asperities is seen as modest near-fault increases in intensity in the cases so far studied.

Paper P50: [Read]

Mitigation Analyses for the Selection of Effective Seismic Retrofit Strategies at a Territorial Scale

Sonia Giovinazzi and Stefano Pampanin

Recent developments of viable and low-cost retrofit solutions within a multi-level retrofit approach, suggest the possibility to implement “standardised” solutions at a urban or territorial scale. However, due to the limited funds available, alternative strategies should be considered in order to define the most effective action plan able to minimise the overall risk. Such mitigation analyses, although not yet codified, are expected to become a fundamental decision making tool for the allocation of funds by local authorities, as is already happening overseas. In this paper the efficiency of different structural mitigation strategies will be investigated within the framework of a seismic risk analysis approach. Alternative mitigation strategies will be examined by combining: 1) alternative retrofit solutions based on different techniques and targeting various performance objectives; 2) spatial distributions of the intervention for targeted typologies. The effectiveness of the aforementioned alternative mitigation strategies will be assessed with reference to a case study area using different mitigation analysis methods, based on a single- or multi-criteria approach within either a deterministic or a stochastic evaluation.

Paper P51: [Read]

Analytical Modelling of Jointed Precast Concrete Beam-to-Column Connections with Different Damping Systems

Geoffrey Rodgers, Geoffrey Chase, Kevin Solberg, John Mander and Rajesh Dhakal

Jointed precast concrete systems typically have low inherent damping and are thus particularly suitable for applying supplemental damping systems. Analytical modelling is utilised to characterise jointed beam-to-column rocking connections, using a rate-dependent tri-linear compound version of the well-known Menegotto-Pinto rule. The analytical model is verified against near full-scale experimental results. The beam-column connections are constructed utilising Damage Avoidance Design (DAD) principles with unbonded post-tensioned tendons. High force-to-volume extrusion-based energy dissipaters are externally fitted to provide supplemental energy dissipation and modify joint hysteretic performance. Multiple joint configurations are analysed, with supplemental damping systems modified to investigate the effect of damping forces on joint hysteresis. Particular attention is given to the re-centring limit. Good agreement between the analytical models and experimental results is demonstrated, with discussion of possible improvements. Overall, system damping behaviour is significantly improved by adding the extrusion based damping system.

Paper P56: [Read]

Vertical Mass Irregularity Effects on the Seismic Performance of Shear Buildings

Vinod Sadashiva, Greg MacRae, Bruce Deam and Cedric Maunoury

Simple models of regular shear-type building structures of 3, 9, 15 and 20 storeys were designed according to the equivalent static method of the New Zealand seismic loading standards, NZS 1170.5 (2004). These models were subjected to the 20 SAC Los Angeles 10 in 50 earthquake records, scaled to various levels and analysed using inelastic dynamic time history analysis considering P-D effects. A probabilistic definition of the change in structural response due to different levels of vertical mass irregularity is provided which may be used as a design tool. Vertical mass irregularity has the most effect on peak inter-storey drift when the eccentric mass is placed either on the very top, or very bottom few storeys.

Paper P59: [Read]

Design Methodology of Concrete Buildings with the Method of Performance-Based Seismic Design

M. Tehranizadeh and H. Daneshva

Nowadays there are large amounts of researches and investigations aim to develop a trustful methodology for performance-based earthquake engineering. To accomplish this objective, the performance assessment and design process has been broken into logical elements. Elements of the process include description, definition, and quantification of earthquake intensity measures, engineering demand parameters; on the other hand, each structural and nonstructural member behavior under the seismic motions which is focus of this paper.

Available design philosophies are not based on the performance-based design concepts so they result in specific performance level for instance “Life Safety” during severe earthquake .In this way, prediction of structure performance during an earthquake is comparatively an art rather than a science because the thought behind the design is strength not performance. Therefore a kind of juxtaposition should be done in order to understand available design codes and their effects on structure and member behavior.

In this paper, several concrete structures have been modeled and designed based on three levels of ductility in ACI318-05 and four different levels of ductility in NZS3101-95 .Each designed member has been taken into consideration carefully and performance the whole structure and its members have been monitored precisely by performing nonlinear analysis. It is observed that we can obtain our desirable performance level with working on structure ductility.

Paper P53: [Read]