Browsing by Author "Perera, DFU"

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item: Conference-Full-text
A comparison of blast and earthquake resistant detailing concepts adopted for reinforced concrete buildings
(1999) Perera, DFU; Jayasinghe, MTR
It is the duty of the professionals involved in the building industry to ensure that the buildings are safe and healthy. However, in many instances such as blasts and earthquakes, the building industry has failed to ensure this which led to many casualties among the general public. It is shown in this paper that the present practices adopted for buildings in Sri Lanka would not be sufficient in this respect and further precautions and improvements should be taken for future buildings. The concepts that can be used at the planning stage for the structural form are highlighted. The methods available for improving the ductility of the structures with reinforcement detailing are also highlighted. The cost increases associated with such practices are presented.
item: Article-Full-text
Cost increases due to earthquake resistant detailing of concrete structures
Perera, DFU; Jayasinghe, MTR
There are two major factors that discourage the use of earthquake resistant design and detailing of structures constructed in Sri Lanka. They are the belief that the earthquake resistant structures will cost a lot more than the normal structures and the misconception that Sri Lanka is located at an area where no earthquakes will occur. On many occasions, the assumption that a particular area is seismically inactive has been proven wrong at the cost of human life and severe destruction to the infrastructure of an area. This is true for Sri Lanka as well since a number of earthquakes have been reported in the recent past in Central India and one event close to Sri Lanka which have hitherto be considered as seismically inactive. British Standard Codes of Practice used in Sri Lanka for structural design does not cover earthquake design and some of the reinforcement details widely adopted are not desirable with respect to earthquake performance. Earthquakes are among the most awesome of natural forces. They occur suddenly, generally without warning, and within 10-20 seconds can turn cities into wasteland. Most earthquakes around the world occur on well defined tectonic plate boundaries, and are known as inter-plate earthquakes. Earthquakes within a tectonic plate are called intra-plate and are spread across the whole of the plate rather than being confined to the boundaries. These occur less frequently. Since Sri Lanka is located away from well known plate boundaries, any earthquake occurring in Sri Lanka is intra-plate type. In an intra-plate area, it is almost impossible to predict the location or likely time of an earthquake event (Hutchinson et al., 1995). However, it is now widely accepted that the risk of earthquakes and their potential for damage especially in heavily populated areas can no longer be ignored. In summary an earthquake event in Sri Lanka may be considered to be low risk but of high consequence
item: Thesis-Abstract
Earthquake and blast resistant reinforced concrete buildings for Sri Lanka
Perera, DFU; Jayasinghe, MTR
Earthquakes and blasts are generally considered as unlikely events by many professionals involved in the building industry. However, in ~any instances, such optimistic views are shown to be wrong at a great loss of human life and property. In many earthquakes and blasts, most of the deaths have occurred due to collapsing of buildings than due to any direct effect of the earthquakes or blasts. Therefore, it is of primary importance to ensure that buildings will not collapse which requires a considerable enhancement in the ductility of the building. However, even properly designed ductile buildings can suffer extensive damage if there are certain undesirable features. Thus, it is suggested to include earthquakes and blast resistance principles at three different levels; those are the use of desirable structural forms, building planning provisions and the improvement of ductility through detailing. The steps that can be taken with respect to these three areas are investigated by comparing the desirable practices with those presently adopted. The methods for adopting such improvements to reinforced concrete buildings constructed in Sri Lanka are determined with case studies. It is shown that most of the measures taken to enhance the earthquake resistance could also enhance the blast resistance. However, some other measures would need a comprormse. These compromising solutions are also adopted. One of the primary reasons for not promoting earthquake and blast resistant construction by engineers and the clients is the cost involved. Therefore, the likely extra cost involved in adopting the recommended practices was determined. It is shown that the extra cost of adopting earthquake resistant details would be about 2 % of the total cost of the project. When blast resistance is also included, it would be about 2.5 % of the total cost. This indicates that it is worth adopting earthquake and blast resistant details for the government buildings such as administrative offices, schools, hospital buildings etc and also large public buildings such as supermarkets, banks, shopping malls, etc. built in future. Such measures would be useful in minimising the destruction and the economic loss that would occur in such events.
item: Conference-Abstract
Earthquake resistant detailing of reinforced concrete structures
(1998) Perera, DFU; Jayasinghe, MTR