SAFETY IN BUILDING

Taranaki Daily News, 29 April 1931, Page 12

SAFETY IN BUILDING

EARTHQUAKE RESISTANCE US-E OF REINFORCED CONCRETE. ARCHITECT'S RECOMMENDATION. The use of a certain amount of reinforced concrete in building construction is advocated by Mr. Henry E. White, architect and consulting engineer. Auckland, in a report he has prepared on the failure of buildings in Hawke’s Bay after visiting the devastated areas there. “It will appear,” lie says, “that the form of construction which will most readily provide the qualities of rigidity and unity in the foundations, walls, floors and roofs of buildings is one which will involve the use of a certain amount of reinforced concrete. New Zealand is admirably situated for such construction, there being abundance of excellent gravel and clean sand available at very low cost i almost every locality.” As a result of his investigations Mr. White was forced to the conclusion that a large amount of building construction carried out in Hawke's Bay had been designed and executed without knowledge of the fact that the district was situated adjacent to a fault line subject to earthquakes. Architects practising in the area, including himself, never contemplated a severe seismic disturbance, and very few buildings were constructed -x fabricated

steel or reinforced concrete. Mr. White found that timber buildings generally, as in residential construction, resisted the shocks remarkably well. Brick buildings, with interior floors, partitions and roofs constructed of timber, fell badly. In most cases the brick exteriors were entirely shaken down, but generally the interior floor and roofs were left standing. Hollow walls were a source of great danger, as also were gable ends and parapets and brick chimneys. MOST TRAGIC FAILURES. Buildings with brick walls supporting reinforced concrete floors and concrete roofs provided the most tragic failures of all, the floors being too rigid and too heavy for the brick walls to support them during oscillation. Unless it is of uneconomical thickness there is not sufficient strength in an ordinary brick wall to support concrete floors or roofs during earthquake disturbances. The reduction of shop window space should now be considered in towns where there is considerable foot traffic along the main thoroughfare, says Mr. White. A maximum glass area is generally insisted upon by shopkeepers, and this prevents architects from designing, their buildings with sufficient corner-bracing between the side walls and facade, or from having a sufficient width of pier to resist longitudinal movement of the bressummer. A factor which also contributed to the general destruction was the suspension type of street awning; and Mr. White says it is a debatable question whether street awnings should be permitted in future within the earthquake zone. DANGEROUS WATER TANKS. A further practice of great danger, and one that wrecked and assisted in the destruction of buildings in Hawke’s Bay, was the construction of water tanks in towers on the roofs or within the roofs of buildings. It was noted, more particularly in the construction of freezing works, that cattle ramps and also elevator ramps and constructions of that kind caused tremendous damage tp valuable buildings. Such ramps really acted as battering rams. There were several buildings of reinforced concrete in the affected area, says Mr. White, but although some of these failed it must not be considered that this type of building’ cannot be constructed satisfactorily to resist major earthquake shocks. It is considered that the failures which occurred in reinforced concrete buildings were attributable to one of three "'uses: Failure of the foundations or subsidence of the ground upon which the buildings were erected; a general slenderness in design; or the lack of diagonal bracing, too much dependence being placed upon the brick walls, some of which were built of inferior mortar. All these defects could be easily overcome without unduly increasing the cost of construction.

REMODELLING AND ITS DANGERS.

One of the conclusions at which Mr. White has arrived is that the remodelling of old buildings to form theatres, ■public halls, or any other kind of building where meetings of the general public are held should be entirely prohibited. Hotels, apartment flats, boarding houses, hospitals, churches, schools and colleges should oe constructed throughout entirely of reinforced concrete; and in every ease such buildings should be designed in what is known as whole or closed designs, both, horizontally and vertically. Buildings generally should be constructed rectangular in shape haying walls, where practicable, of equal height throughout, following the closed design type, complete within itself. The elimination of useless ornament, which Mr. White recommends, yvill make larger funds available for general construction work. “It is the writer’s opinion,” says Mr. White in conclusion, “that there is only one type of building which will satisfactorily resist seismic shocks; and while it is impossible to guarantee that any particular' building will safely resist damage from a major earthquake, it is considered that the recent happenings in the Hawke’s Bay district were as severe as any disturbances that have happened in any inhabited quarter of the world during historical times; and from general observations the writer is of opinion that buildings constructed of reinforced concrete, embodying, inter alia, the foregoing recommendations will most satisfactorily resist the destructive effect of earthquake’ shocks.”