'QUAKE RESISTING.

Auckland Star, Volume LXVI, Issue 50, 28 February 1935, Page 17

'QUAKE RESISTING.

BUILDING NEEDS. LESSON FROM NAPIER. THE ECONOMIC ASPECT. "I am inclined to think that in our pwn experience the results of the Napier earthquake caused rather a mistaken estimate to be made as to the supposed failure of existing methods of building construction," said Mr. C. Reginald Ford, past president of the New Zealand Institute of Architects, in a paper delivered before that body in Wellington yesterday. The paper dealt comprehensively with the general effect of earthquakes on buildings, the best methods of earthquake resistance, the lines of research necessary for further information, and, finally, the economic aspect.

"It was natural enough, perhaps, when surveying the ruins of what had been a fair city, to assume that all accepted • forms of building construction were unsound and that a complete revolution was necessary," said Mr. Ford. "But later reflection brings to mind that, after all, tho great destruction at N"apier was due in no small measure to several factors not necessarily indicative in themselves of any_ failure of tho existing methods of building construction if properly understood an 1 faithfully carried out.

"Amongst these factors were the existence of a number of obsolete buildings erected in earlier years and altered at intervals subsequently without thought or skill, and of many buildings of more recent date in which were present elementary faults in design, even for normal conditions. There were, too, instances of buildings, both old and new, the construction of which embodied details and methods which observation of buildings damaged or destroyed in other earthquakes have shown to be dangerous and which might easily have been avoided.

"Worse still, there were, too, many examples of careless or in some cases culpably bad or dishonest workmanship which should be made impossible in the future. Under earthquake conditions scamped and dishonest workmanship is little short of criminal. One Change Imperative. "In one particular a revolution ill building construction in New Zealand is, however, necessary. That is in the recognition of the very real possibility of buildings being subjected by earthquake shock to horizontal vibrational stresses and the need in future construction of the abandonment of those methods of design and details of construction which experience has proved to be dangerous under such conditions. This will not involve the adoption of any very revolutionary or costly changes in the design of the smaller buildings. But, although the changes called for may not be revolutionary, they are none the less imperatively necessary, and to ignore this necessity is to invite disaster."

Mr. Ford referred to the difference of opinion as to rigid or flexible frames, of which latter the ordinary wood house, which made such a good showing in the earthquake, was an example. His paper dealt with the technical aspects of the argument, and came to tne conclusion that tho authorities to-day favoured the rigid type. First Requisite Common Sense. While a sound knowledge of principles was essential, tho first requisites were a wise judgment and common sense. In that respect, he referred to one difficulty in the proposed new building code. "Were all building construction and the approval of designs in the hands only of trained and competent men," he said, "it would be a simple matter to frame a building code which would state certain principles of design and give limiting stresses, leaving the determination of all details to the designer. But this ideal condition is nonexistent, and it unfortunately seems necessary that a code should be perhaps more fuil and restrictive in details than is desirable." Mr. Ford said he realised the importance of the economic aspect —that was the additional cost of designing to • resist earthquakes, about which there had been altogether too much loose talk. Dr. Naito, of Japan, had stated that the cost of designing a building to resist a horizontal strain of one-tenth of nravity was approximately 10 per cent upon the total cost of the whole building, though that would vary with conditions. Mr. Ford suggested another noint of view. "The whole idea of extra cost is wrong," he said. "If aseismic design is necessary, then any cost involved is no more of an extra cost than is the cost of resisting the force of gravity, or that of the provision of sanitation and hot-water heating."

Mr. Ford's Summing Up. "To sum "p, earthquakes are a more common phenomenon than is usually recognised. In the light of present knowledge it is definitely possible to design buildings to resist earthquake shocks of great intensity at a reasonable additional cost," Mr. Ford said.

"Moreover, not to do so is, in New Zealand at least, to invite disaster. A great deal can be done to make buildings safer by simple changes in practical building construction based upon the lessons of the past. In the caso of tlie larger buildings data is available to make the analysis of aseismic building frames possible. Nevertheless, our knowledge as to the nature and extent of earth movements is incomplete, and further research work is urgently necessary. The effect of discontinuity between the foundation and the soil and method of effecting it should be studied, and there is a big field for research into tho problem of the analysis of building frames when subjected to earthquake force."