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Vierendeel girder bridge introduced in America
624
CURRENT To~ics.
[J. F. I.
Vierendeel Girder Bridge Introduced in America.--L. T. EVANS. (Engineering News Record Vol. 117, No. I4.) A contract was let recently for the first of eight structural steel Vierendeel girder bridges which will span one of the channels of the Los Angeles County flood control project. Riveted design was selected. This is believed to be the first bridge of this type to be employed in this country, although such rigid panel trusses without diagonal members have been used extensively in Europe and particularly in Belgium, the country of their origin. Since the Los Angeles bridge is to be built in a congested part of the city, many complications arose. The original channel was much narrower than the one selected for this improvement, so that the bridge span was increased from about 45 to 96 ft. Fixed channel and street grades limited the distance between road surface and the underline of the span to about 3 ft., thereby eliminating a deck structure. Visibility was essential as side streets intersected very close to the ends of the bridge. The city officials objected to any overhead bracing or to the use of a middle support. In addition to these requirements, it was desirable to use a vertical end post high enough to mark clearly the beginning of the bridge, thereby eliminating an arch or incline chord structure. After taking all of these factors into consideration, a Vierendeel girder was chosen. R. H. O.
CURRENT To~ics.
[J. F. I.
Vierendeel Girder Bridge Introduced in America.--L. T. EVANS. (Engineering News Record Vol. 117, No. I4.) A contract was let recently for the first of eight structural steel Vierendeel girder bridges which will span one of the channels of the Los Angeles County flood control project. Riveted design was selected. This is believed to be the first bridge of this type to be employed in this country, although such rigid panel trusses without diagonal members have been used extensively in Europe and particularly in Belgium, the country of their origin. Since the Los Angeles bridge is to be built in a congested part of the city, many complications arose. The original channel was much narrower than the one selected for this improvement, so that the bridge span was increased from about 45 to 96 ft. Fixed channel and street grades limited the distance between road surface and the underline of the span to about 3 ft., thereby eliminating a deck structure. Visibility was essential as side streets intersected very close to the ends of the bridge. The city officials objected to any overhead bracing or to the use of a middle support. In addition to these requirements, it was desirable to use a vertical end post high enough to mark clearly the beginning of the bridge, thereby eliminating an arch or incline chord structure. After taking all of these factors into consideration, a Vierendeel girder was chosen. R. H. O.