Keynote Address Learning from Hawke's Bay 1931 Earthquake Performance Assessment and Retrofit Decision Making for Risk Mitigation Behaviour of Walls and Piers Understanding Reinforced Concrete Behaviour Modelling Earthquake Performance Earthquake Performance Poster Papers Design and Development 

Earthquake Engineering N Z Business Cluster Leveraging Benefits and Opportunities, a Facilitator's Perspective

Graeme Carroll

In this paper we present our goals, method of operations, our successes and expectations for the future. Earthquake Engineering NZ (EENZ) is a Wellington-based NZ network of over 30 members comprising consultants, device manufacturers, researchers, educators, insurers, seismologists, architects, structural engineers, building services engineers, urban planners, emergency management professionals, business continuance advisers, local government officials, loss assessment experts, safety advisors and cost engineers. The business of Earthquake Engineering NZ (EENZ) members is to deliver practical and economic solutions that reduce the consequences of earthquakes on communities. The focus of the Earthquake Engineering NZ Business Cluster is on overseas work that would not otherwise be generated by individual members. The role of EENZ is as a forum for members to share knowledge, develop new ideas and approaches for generating business, and to facilitate co-operation amongst members in pursuit of worthwhile prospects.

Paper P43: [Read]

Restoration of Earthquake Damaged Water Distribution Systems

Peter Davenport, B. Lukovic and Jim Cousins

This paper reports progress made to date of a research project that investigates the post-earthquake functioning of communities. Our research programme is aimed at minimising post-earthquake disruption and we suggest that the greatest trauma for the survivors in the epicentral area will be due to loss of water, loss of shelter, loss of services and loss of employment caused by damage to structure and infrastructure.

Experience shows that damage to infrastructure can have far-reaching consequences. Loss of potable water, for example, was a major reason for the evacuation of a third of the population from Napier, NZ in 1931. On Rokko Island, Kobe, 1995, there was minimal damage to the mostly high-rise housing blocks but the entire 30,000 population had to be evacuated because the water supply was lost.

Using models for the seismic behaviour of buried pipes and other components, we evaluate the impacts of various sizes of earthquakes on the functioning of a water supply network and the effort and time for various restoration strategies. In this way, we test strategies for reducing the post-earthquake restoration time. A GIS (Geographical Information System) environment is used for the study area, near Wellington, NZ, representing a typical urban water supply system. The methodology to model seismic hazard on a water network could be adapted to hazards other than earthquake and lifelines other than water.

Paper P44: [Read]

Retrofitting of Masonry Walls using Shotcrete

Mohamed ElGawady, P. Lestuzzi and M. Badoux

This paper presents results of static cyclic tests investigating the in-plane behaviour of URM walls retrofitted using shotcrete. Three half-scale walls were built, using half-scale brick clay masonry units and weak mortar. One specimen was tested as a reference specimen. Another one was retrofitted on a single-side using a 40 mm thick layer of shotcrete. The last one was retrofitted on a double-side using 20 mm thick layers i.e. both specimens had the same shotcrete thickness and reinforcement. The tests revealed that retrofitting using shotcrete was able to increase the lateral strength of the specimens by factor of approximately 3.6. Retrofitting on double-side had more ductile failure and energy dissipation.

Paper P45: [Read]

Benefit-cost Study for 369 Apartment Buildings in Istanbul

David Hopkins, Metin Arikan and Richard Sharpe

A specially designed benefit-cost study was made of retrofitting of residential buildings as part of a feasibility study for the Government of Turkey funded by a World Bank loan. The study was part of the Marmara Earthquake Emergency Reconstruction project aimed at mitigating seismic risks in Istanbul and reducing the social, economic and financial impacts of earthquakes. The 369 mainly reinforced concrete buildings examined were built between 1963 and 1992, typically 6 storeys high, and contained over 4000 apartments.

Detailed analyses of the costs and benefits of two retrofitting solutions for each building were made. Costs assessed included construction costs, alternative accommodation, and loss of rental during construction. Benefits assessed included reductions in damage, injury, loss of life and post-earthquake housing. The study examined the net benefits of taking action through retrofitting or replacing each building, for a range of times occurrence of the M7.2 scenario earthquake. The information from the study will be valuable to owners, the Bakirkoy Municipality and to other municipalities in developing approaches to retrofitting of residential buildings.

Paper P46: [Read]

Decision Making Tools for Seismic Risk

Gregory MacRae

Earthquake risk, and the benefits and deficiencies of possible risk mitigation options, need to be communicated in such as way as to allow appropriate and responsible decision-making. This paper describes the difficulty in making a decision about whether or not to consider earthquake in design or retrofit. Then, a series of visual/graphical tools for presenting the benefits of design and retrofit options for new and existing structures are described. These tools, which are developed based on a life cycle methodology, allow a quantitative assessment of the best technical solution as an aid to decision-making. The need for standardization of loss estimation methods is emphasised.

Paper P47: [Read]

Seismic Retrofitting of Unreinforced Masonry Buildings in Italy

S. Frumento, S. Giovinazzi, S. Lagomarsino and S. Podestà

The Italian heritage building stock is dominated by unreinforced masonry buildings widespread on the whole territory with rammed earth buildings peculiar of some regions. A major effort is given to strengthen or retrofit these buildings in order to improve their safety under seismic loading as well as to preserve them as memory of the ancient art of builders and as constitutive elements of the anthrop-environment. This paper describes traditional seismic retrofit interventions adopted in Italy. These retrofitting interventions, revised according to the modern technologies, derived from historical concept of aseismic devices (i.e. metallic tie-rods, circumferential tie-rods, buttresses, “diatoni”, wall connections, partial reconstruction of walls) suggested to the builders’ crafts by observation of earthquake damage and imposed by the past technical rules. A good degree of confidence on the feasibility, compatibility and effectiveness of these techniques for URM buildings is guaranteed after having been extensively tested during the centuries. Recently, technical national code-guidelines for the seismic retrofit of existing URM masonry buildings have been prepared with the specific purpose to help practitioner engineers to implement these solutions.

Paper P48: [Read]

Spectral Evaluation of High Force-volume Lead Dampers for Structural Response Reduction

Geoffrey Rodgers, Caleb Denmead, Nicholas Leach, Geoff Chase and John Mander

Response spectra analysis across multiple earthquake suites is used to investigate the reductions in structural response from the addition of lead extrusion damping, based on ongoing research with high force/volume devices suitable for packaging in beam-column connections. Reduction factor statistics are used to characterise the response using suites of ground motions from the SAC project. Regression analysis is used to characterise reduction factors in the constant acceleration, velocity, and displacement regions of the response spectra. Peak damping reduction factors achieved with the addition of extrusion damping equal to 10% of structural weight are approximately 6.5x, 4.0x, and 2.8x for the low, medium and high ground motion suites respectively, based on a validated full-scale prototype device. The results provide initial proof-of-concept in a performance based design context, at experimentally verified forces, for using these devices to increase the seismic resilience of critical infrastructure.

Paper P49: [Read]

Design of Chinese Steel T V Towers

Xing Ma and Zhaomin Wang

The development of Chinese steel TV towers is introduced in this paper. As an example of real project, the design procedure of Qingpu TV tower is presented. After the dynamic characteristics of the structure is analysed, the quasi-static wind loads and seismic forces are calculated based on Chinese design code and a nonlinear spatial truss model is employed to analyse the response of the structure. Calculation results show that the wind-induced structural response is much more severe than seismic response. It is reasonable to omit seismic forces for practical design of steel TV towers.

Paper P50: [Read]

Experimental Study on Concrete Slabs Reinforced by Specially Shaped High-strength Steel Bars

Xing Ma, Guojun Nie, Zheng Zhong and Danda Li

A new type of specially shaped high-strength steel reinforcement named bi-rib deformed steel bar is introduced in the paper. As the bar has very good bonding property with concrete, the mechanical performance of corresponding reinforced members is expected to be superior to normally reinforced concrete members. To investigate the improvement, experiments on concrete slabs reinforced by the type of bar and slabs reinforced by plain round steel bars were carried out in the structural laboratory of Tongji University, during which four 3m-span one-way slabs and one 3m-span two-way slab were tested. Experiment results proved that the specially reinforced slabs had higher strength, thinner cracks and better ductility compared with normally reinforced slabs.

Paper P51: [Read]

Continuous Column Effects on Frame Seismic Behaviour

Y. Kimura and Gregory MacRae

The prevention of an undesirable soft-story in a structure subject to earthquake shaking may be achieved by using well-established capacity design guidelines for moment frame structures. However, similar guidelines are not available for braced-frame structures in which lateral forces are resisted mainly by truss action according to elastic analysis and column moment demands are generally ignored. Also, in some moment-framed structures, it is not also practical or reasonable to perform capacity design. This paper shows that a soft storey mechanism, and large story drifts, may be prevented by providing continuous columns within the structure. These continuous columns may be gravity columns, in-plane, or out-of-plane seismic columns. Relationships for column stiffness and drift concentration within a frame based on pushover and dynamic analyses are developed. An assessment method and example to determine the required column stiffness necessary to limit the concentration of story drift is provided.

Paper P53: [Read]

The Roglider – a Sliding Bearing with an Elastic Restoring Force

Bill Robinson, C.R. Gannon and J. Meyer

The research on a number of new approaches to seismic isolation continues with the development of a RoGlider capable of supporting both light and high vertical loads with an effective co-efficient of friction of ~11% together with an appropriate elastic restoring force. Preliminary tests on prototype RoGliders have been promising.

We will present a model of the double acting RoGlider together with a video of a test of a full size RoGlider. The tests on the full size RoGlider have a maximum displacement amplitude of 600mm while the outside diameter of the RoGlider is ~900mm.

Paper P54: [Read]

An Innovative Seismic Isolation Device/system Suitable for Existing Shallow Foundation Structures

C. Balaji

Earthquake remains as one of the major cause of destruction. However the damages can be reduced down if proper measures taken in the initial design stage itself. The approach is feasible for the newly designed structures leaving the old existing structures to these vulnerable forces. Conventional upgrading techniques are the addition of existing walls and foundations, strengthening of the frames. Most of these techniques often lead to costly consequences such as heavy demolition, lengthy construction, and occupant’s relocation. Such expensive hostile and intrusive approach associated with conventional techniques often deters building owners from retrofitting building for improved earthquake performances. The main purpose of the paper is to access the possibilities of developing an innovative device as a solution for reducing down the seismic response.

Paper P55: [Read]

Displacement Profile for the Displacement Based Design of Moment Resisting Frames

A. Yavas and Ş. Saylan

Damages that occur in structural and non-structural elements during the earthquake are due to lateral displacements. Traditional force based design methods controls displacements at the end of the design. Therefore it is difficult to control potential damages. Direct displacement based design approach that designs the structure for a given displacement profile, can control the potential damages. Direct displacement based seismic design uses the displacement profile as the basis of the design approach. Two different displacement profiles proposed for the direct displacement based seismic design of moment resisting reinforced concrete frame structures. In this study displacement profiles for four, six and ten storey moment resisting frames are determined by using nonlinear time history analysis and compared with the earlier displacement profiles.

Paper P56: [Read]

Keynote Address Learning from Hawke's Bay 1931 Earthquake Performance Assessment and Retrofit Decision Making for Risk Mitigation Behaviour of Walls and Piers Understanding Reinforced Concrete Behaviour Modelling Earthquake Performance Earthquake Performance Poster Papers Design and Development