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

Design, construction and dynamic testing of a post-tensioned precast reinforced concrete frame building with rocking beam-column connections and ADAS elements

A.G. Murahidy, H.A. Spieth, A.J. Carr, J.B. Mander and D.K. Bull

Reinforced concrete structures permitted to rock on their foundations and provide recoverable rotations at the beam-column interfaces offer significant advantages over conventional ductile detailing. A jointed construction philosophy can be applied whereby structural elements are connected with unbonded steel tendons. Supplemental damping is provided by replaceable flexural steel components designed to deform inelastically. A multi-storey test building of one quarter scale has been constructed and tested on a uniaxial earthquake simulator at the University of Canterbury. A computer model has been developed and a set of preliminary design procedures proposed.

Paper P31: [Read]

Modelling of post-tensioned precast reinforced concrete frame structures with rocking beam-column connections

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

Recent earthquakes have identified that buildings designed to a performance based criteria need not only resist the ground excitation but remain, in many situations, undamaged once ground motions have abated. One promising approach is the use of post-tensioned frame structures assembled from precast reinforced concrete members.

A modelling approach has been developed which provides for the accurate simulation of the developed compression zone and accounts for the shift of the neutral axis in the contact area over the duration of earthquake motion. Furthermore, the beam elongation effects are captured as well as the effects on the structure due to the lengthening of the post-tension tendons.

A new multi-spring contact element has been developed and included in the finite-element program RUAUMOKO. The distribution of the stiffness along the contact area of the rocking elements is calculated based on a number of different integration schemes. The model is compared with experimental displacement controlled tests undertaken with beam‑column subassemblies and experimental dynamic tests of a multi‑storey frame structure.

Paper P32: [Read]

Preliminary results from experiments on hollow-core floor systems in precast concrete buildings

R.A. Lindsay, J.B. Mander and D.K. Bull

Recent earthquake engineering research undertaken at the University of Canterbury has aimed at determining whether New Zealand designed and built precast concrete structures, which incorporate precast concrete hollow-core floor slabs, possess inadequate seating support details. A full scale precast concrete super-assemblage was constructed in the laboratory and tested in two stages. The second stage is a follow-up study on the earlier work of Matthews. This paper reports preliminary results of the second stage of experiments where improved seating details are investigated. These consist of a simple (pinned-type) connection system that uses a low friction bearing strip and compressible material for the supporting beams together with a 750mm wide timber infill between the perimeter beams and these precast floor units. Test results show a marked increase in performance between the new connection detail and the existing standard construction details, with relatively small amounts of damage to both the frame and flooring system at high lateral drift levels. Interstorey drifts in excess of 3.0% can be sustained without loss of support of the floor units with the improved detailing. Recommendations for future design and construction are made based on the performance of the super-assemblage test specimen.

Paper P33: [Read]

Earthquake damage to passive fire protection systems in tall buildings

G.S. Sharp and A.H. Buchanan

This paper investigates the extent to which earthquake damage to passive fire protection reduces fire safety in tall buildings.

Currently in New Zealand there are no legislative design criteria for the event of fire following an earthquake. Some passive fire protection systems such as gypsum plasterboard walls are very vulnerable to earthquake damage. This damage can lead to a reduction in the fire resistance ratings, thereby threatening the fire safety of the occupants, particularly for walls protecting the escape routes from buildings.

In this study a model was developed to calculate factors of safety as a ratio of available and actual escape times in burning buildings. In a worst case scenario, the model considered the possibility of fire occurring on the ground floor adjacent to the main escape routes from the buildings. The study included the results of recent research which shows that gypsum plasterboard walls, not damaged by earthquake but exposed to realistic fires, may fail in much shorter times than the published fire resistance ratings.

It was concluded that for fire following an earthquake in buildings greater than about ten stories, in which the sprinklers do not operate and the walls are damaged, the occupants may be unsafe because the expected escape time is greater than the expected failure time of the fire rated walls surrounding the escape route.

Paper P34: [Read]

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