Fire Testing Following an earthquake in a populated area

Following An Earthquake

The structural damage caused by an earthquake in an urban area is often compounded by ensuing fires, many properties which have survived the initial shock may subsequently be destroyed. Destructive fire test trials conducted at the Building Research Establishment (BRE) in Great Britain have compared the cementitious Cintec anchor against both mechanical expansion and resin systems of reinforcement. All were subjected to temperatures of 1200 ºC. In these tests the resin ties failed on average after 1/2 hour heat exposure. Metal expanders were capable of longer periods of resistance of 1hour -plus, but could fail prematurely if they were not sufficiently torqued. The best results were achieved by the Cintec anchors which were capable of at least 2 hours resistance. This extra time may prove sufficient in maintaining the structural integrity of a building while a potentially devastating fire is brought under control.

Trial by fire

Cintec anchors were installed in the 200 year old Fullers Brewery in London (right).A fire however, subsequently destroyed the interior of the building. Although subjected to extremely high temperatures the anchors remained intact, and pull out tests revealed that they still performed to their original design specification. Had a resin alternative been specified, they may well have melted. Where Cintec anchors had been installed there were no cracks in the structure. Their earlier performance ensured they were used to consolidate brickwork delaminated by the heat and allow internal repairs without the risk of further collapse.

Pull out tests revealed the Cintec anchors still performed
within specification even in the walls worst effected.

Case History: Newport Heights Elementary School, Washington State, USA

Newport Heights Elementary school, Washington, was built in the early 1960 ’s,well before modern U.S. seismic codes were in place. Although the one-storey buildings have a well designed and well-built roof system, the entire exterior envelope was composed of concrete masonry (CMU) infill walls. These walls were neither anchored nor reinforced to the main structural frame for in-plane or out-of-plane forces. Furthermore, the hollow cells of the CMU were completely ungrouted. Reinforcement was clearly necessary to avoid the risk of collapse during a seismic event. To maintain floor space, steel plate "backer bars "were chosen to reinforce the walls. These were anchored to the floor slab and the roof structure with standard fasteners. The connection between the backer-bars and the hollow CMU required a more custom connection: an anchor that could be set through a small hole into a hollow cell that could then be filled with grout (while not filling the entire vertical cell) and finally, anchored to the backer bars with a head screw. Cintec developed an anchor specifically tailored to the project ’s needs. A number of anchoring devices had previously been tested but only Cintec met the load requirements. Their swift and smooth installation convinced the School District and the General Contractor that Cintec anchors were the right choice. In North America Cintec is also involved in seismic projects for Pacific Gas &Electric and the Mission of San Juan Capistrano.

Case History: State Library of South Australia, Adelaide

The State Government of South Australia has commenced a programme of upgrading public buildings to meet earthquake code requirements. Adelaide experienced an earthquake in 1954 which, whilst causing no major damage, made the city more aware of the dangers from earthquakes in Australia than most other population centres.

Adelaide is noted for its fine 19th century buildings and one of the most attractive of these is the State Library of South Australia in North Terrace. The ground floor of the building is supported over the basement by brick vaulting topped by a thin layer of unreinforced concrete. Clearly, this floor would be liable to collapse in an earthquake. The adopted solution was to place Cintec anchors in both directions at the ends of the building with transverse tie-rods elsewhere. The anchors were fabricated from 25 mm (1 inch) stainless steel "Grip-Bar " and were 19 metres (62.5 ft) and 15 metres (49 ft) long.

In some locations, following removal of the flooring it was found that the floor was much shallower than originally measured, and too thin to drill safely. The anchors were able to be placed in a channel sawn in the floor, still managing to achieve the required bond with the brickwork and yield the composite action required. This installation modification was yet another demonstration of the versatility of the Cintec anchoring system.

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