STEEL BRIDGES.

Taranaki Daily News, 13 May 1916, Page 8

STEEL BRIDGES.

AMERICAN DESIGNS. INFERIOR TO NEW ZEALAND. PRODUCT. Christehurcii, May 10. In the course of an address to members of the New Zealand Society of Civil Engineers to-night, the president (Sir. R. W. Holmes, chief engineer of the Public Works Department) made interesting observations regarding steel bridges. He said the opinion was generally accepted by the public that the United States lead the world in regard to progress in the arts and sciences. Many believed American designs for machinery and structures n'ere beyond cavil. That was true in some cases in this country, but the general examples of American steel bridges could not by any stretch of the imagination be considered examples of good design. Important points were sacrificed in the endeavor to produce a cheap article and our own manufacturers. In the steel truss 'bridge, important on a main road' carrying heavy traffic, the horizontal bracing of the top chord was entirely omitted. Spans of about 100 ft each had top .chords about 80ft long. This bridge with its horizontal columns 80ft long was subjected to heavy stresses due to direct compression and bending, and it was unprovided with lateral stiffeners. The result was heavy vibration of the structure during the passage of loadsv and this would in time cause general deterioration of all parts and slackness of the plates. The number of rivets was less than What experience ha 4 shown to be necessary to ensure durability and safety. There was no necessity to go outside New Zealand for steel bridges. We had men able to meet all requirements in the way of design, and workshops to manufacture from the designs in a manner of which any nation might be proud.