2010 NZSEE
Conference
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2010 NZSEE Conference |
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Contents |
Keynote Address Tribute to Tom Paulay Session 3 Session 4A Session 4B Session 5A Session 5B Session 6 Session 7A Session 7B Session 8A Session 8B Poster Session Seismic Retrofit of a Large Power Boiler with Base IsolationRichard Sharpe, Michael Lee and John Reid In order to improve the seismic resilience of a large (700 tonne) steam boiler, lead-rubber bearings were inserted beneath it during its annual shutdown for maintenance. Such a retrofit is not uncommon for buildings. However, operational constraints, high temperatures, expansion allowances and connecting ducts, structures and services provided a challenge for the design team. An innovative approach was required to meet the requirements for certification of the boiler as a pressure vessel subject to earthquake loading. A three-stage approach from proof of concept to detailed design was followed, and the bearings were installed during September 2009. This paper describes the analysis and design process, the steps taken to protect the bearings from heat with a combination of simple and space-age materials, and the installation. Paper P06: [Read] Predicted and Observed Performance of Masonry Parapets in the 2007 Gisborne EarthquakeR.A. Davey and E.L. Blaikie The December 2007 magnitude 6.9 Gisborne earthquake caused damage to mainly unreinforced masonry buildings in the Gisborne City CBD, including the collapse of 22 parapets. A time-history record of ground shaking caused by this earthquake is available from a strong motion recorder located in the CBD. These circumstances provided an opportunity to compare the observed responses of unreinforced masonry parapets in an earthquake with the responses predicted by assessment procedures given in the New Zealand Society for Earthquake Engineering (NZSEE) publication “Assessment and Improvement of the Structural Performance of Buildings in Earthquakes”. A survey was made of 101 parapets, of which 19 had collapsed, to obtain the data necessary to analyse their earthquake responses using the NZSEE procedure. The main variables considered were: orientation relative to components of the ground motion, parapet height above support level, the height of the support level above ground, and parapet thickness. It was concluded that the NZSEE procedures are not a good predictor of the risk that a particular parapet would collapse, and it was found that a significant number of the parapets that were predicted by the NZSEE method to be safe from collapse under the recorded ground motion, collapsed. Reasons for the poor correlation of predicted and observed behaviour were reviewed and improvements to the procedures proposed. The paper also discusses the possible effect of previous earthquakes in 1966 and 1993 on the observed damage in 2007. Paper P07: [Read] Earthquake Resistance of Bridges With Friction Slab AbutmentsJohn Wood Findings from experimental and numerical research on the force resistance available from passive pressure and friction resistance on friction-slab type bridge abutments both translated against and away from the backfill in earthquakes are presented. Application of the research is illustrated by comparing the resisting forces on the abutments of three State Highway bridges constructed with friction-slab type abutments with the longitudinal earthquake design forces acting on the bridges. Paper P08: [Read] Managing earthquake risk – Whakatane experienceJ.R. Farrell and Y. Kumar The Building Act 2004 requires all local authorities within New Zealand to formulate and implement a policy to identify and manage earthquake-prone buildings within their jurisdiction. The objective of the policies is to minimise risks to public safety posed by these buildings. The Whakatane District Council developed its Earthquake-prone Buildings Policy in 2006. The technical assessment component of the Council’s policy is based on the NZSEE Guidelines (2006). The Council, with the help of GHD Ltd, has recently commenced implementing its policy. Issues surrounding the procedure for initial evaluation of targeted buildings (IEP) according to the New Zealand Society of Earthquake Engineering’s guidelines are discussed. The Whakatane district experiences earthquakes frequently. The most damaging earthquake was the Edgecumbe Earthquake in 1987 (6.2 Richter scale) where shaking intensities of MM7-8 (Modified Mercalli scale) were experienced. More recently there have been numerous swarms of earthquakes centered off the coastline around Matata. Implementation of the Council’s earthquake-prone building policy therefore has a high degree of relevance and timeliness. In the course of carrying out the work, challenges such as implementing the policy during recessionary times, managing the potential scale and impact of knowledge gained through the project upon the Council’s strategic growth strategies, developing a robust system of tracking potentially earthquake-prone buildings and their subsequent management, and adopting a flexible proactive approach with stakeholders, have all had to be positively managed in order to complete the delivery of the first major milestone of the project. Paper P09: [Read] Keynote Address Tribute to Tom Paulay Session 3 Session 4A Session 4B Session 5A Session 5B Session 6 Session 7A Session 7B Session 8A Session 8B Poster Session |