Session 1 Session 2 Session 3 Session 4 Session 5 Session 6 Posters 

Lesson for the new Building Act: Rigour Matters

D.C. Hopkins

The new Building Act places more emphasis on the need for technical rigour in all phases of the building process - in design, design review, design certification, product accreditation, construction practice construction monitoring and construction compliance certification. Coming under the spotlight are both people and processes:

People in terms of the closer definition of the responsibilities they take, a more focused requirement for personal accountability, and more exacting requirements to demonstrate appropriate skills and experience.

Processes in terms of the greater scrutiny from the regulator designed to effect improvement.

In the wake of concerns with weathertightness of buildings and the issues raised by John Scarry, this paper examines the key issues facing the engineering profession, and particularly structural and earthquake engineers. Both IPENZ and the BIA have reported on matters requiring attention. These provide a timely reminder of the need for every professional involved in delivering buildings and structures to place greater emphasis on technical rigour from design concept to completion.

There is a need for structural and earthquake engineers to get the message across first to its members, and then to the community that they will be taking a new attitude that places value on technical rigour throughout the design, certification and construction process.

It may be desirable that structures be designed and built on time and within budget, but it is absolutely essential that they be built to be safe and fit for their purpose.

The opportunities presented by the requirements of the new Building Act (to be) must be seized by the profession to effect changes that place increased emphasis on the imperatives of safety of our structures.

For those responsible there is no other way of moving ahead.

Paper P13: [Read]

Determination of seismic design forces for slender precast slab structures

B.J. Davidson

The development of simple models to determine the seismic design forces for slender precast slab structure is described. The results from initial analyses using these models indicate that the seismic design actions that these structures undergo could differ markedly from values that may be obtained from simpler methods of analysis.

Paper P14: [Read]

Seismic performance of post-tensioned precast concrete beam to column connections with supplementary energy dissipation

H.A. Spieth, D. Arnold, M. Davies, J.B. Mander and A.J. Carr

This paper presents results of an experimental study together with companion analytical modelling of two distinctly different precast concrete beam-to-column joint connections. The first consists of precast concrete beams with armoured end connections connected directly to the column, while the second is a connection offset away from the column at about the ¹/₈ point within the span. In both cases the beams are connected via unbonded post-tensioned high strength prestressing threadbars to a prestressed concrete column. Lateral loading tests were conducted up to ±4% drift with and without supplementary mechanical energy dissipators. The results show that the nonlinear moment-rotation performance can be accurately modelled. From this study it is concluded, that with appropriate armouring of the precast members, damage can be avoided to the connection, while the entire structure is self-centred following an earthquake. These desirable performance features lead to the possibility of immediate post-earthquake serviceability of concrete frame structures.

Paper P15: [Read]

Earthquake scaling for inelastic dynamic analysis of reinforced concrete ductile framed structures

P. Dong, A.J. Carr and P.J. Moss

An earthquake (or a suite of earthquakes) is needed when carrying out inelastic dynamic analysis of a reinforced concrete ductile framed structure. The earthquake should be scaled so as to make its spectral accelerations to match the elastic design acceleration spectrum for the structure to match the elastic code design base shear implied in New Zealand loading code, NZS4203. Techniques and relevant scaling methods are available. However, the maximum base shear obtained from the scaled earthquake for all current scaling methods may not match the code design base shear.

To solve this problem, six different scaling methods are applied to scale four different earthquakes for a ductile framed reinforced concrete structure designed according to the current New Zealand codes using capacity ductile design. By comparing the maximum responses in terms of the maximum base shears, inter-storey drifts and spectral accelerations to the scaled earthquakes with the corresponding design values, the advantages and disadvantages for those scaling methods are identified, leading to a scaling method for which both the design base shear and design inter-storey drift can be matched simultaneously. Finally, a procedure for earthquake scaling is recommended.

Paper P16: [Read]

Review of seismic provisions of historic New Zealand loading codes

P.N. Davenport

New Zealand currently has a well-respected loadings code which has evolved over a considerable period. This paper presents an overview of the various loadings codes from before the 1931 Napier earthquake to the present, including the current draft revision. The seismic requirements which have changed are discussed and compared. These changes in the seismic requirements have implications on the seismic risk profile of the present building stock.

Paper P17: [Read]

Where is that new loadings Standard?

A.B. King, G. McVerry, R.C. Fenwick, D.K. Bull, A. O’Leary, R. Jury, I. Brewer and C. Clifton

This paper provides an update of progress that has taken place over the last 18 months in the development of the new Earthquake Loadings Standard. In that time this standard has become dis-jointed, in that is it is no longer a joint Australia/New Zealand Standard.

The separation has permitted a New Zealand focus to be reintroduced. This focus has permitted several changes such as the performance objectives being clarified and linked more directly with expectations from the material standards. In addition, the seismicity maps have been slightly modified to account for new science, variable S_p provisions have been introduced, a minimum base shear has been reintroduced, permissible interstorey drift limits have been revised, detailing is more closely linked to material strains (section curvature) and the integrated time-history analysis procedures re-assessed, particularly when near-fault effects are present.

Paper P18: [Read]

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