LOADS ON NEGATIVE-PROJECTING CONDUITS

LOADS ON NEGATIVE PROJECTING CONDUITS WERE STUDIED TO USE THE MEASURED VALUES OF SETTLEMENTS FOR USE IN SPANGLER'S LOAD THEORY. THIS STUDY IS DESIGNED TO: (1) DETERMINE THE LOADS ON THREE NEGATIVE PROJECTING CONDUITS, AND TO OBSERVE THE ACTIONS AND FACTORS WHICH AFFECT THESE LOADS, AND (2) UTILIZE THE DATA IN THE DETERMINATION OF A RELIABLE METHOD AND OF SAFE VALUES OF CERTAIN CONSTANTS FOR CALCULATING THE PROBABLE MAXIMUM LOADS ON NEGATIVE-PROJECTING CONDUITS. LOAD AND SETTLEMENT DATA ARE PRESENTED SHOWING THE USUAL SEASONAL VARIATIONS. THESE LOAD AND SETTLEMENT DATA ILLUSTRATE THE VARIATIONS WHICH SHOULD BE EXPECTED FOR SIMILAR CONDUITS WITH SUPPOSEDLY SIMILAR LOADING CONDITIONS UNDER FILLS OF SIMILAR MATERIALS. THE LOAD RECORDS ARE SUMMARIZED FOR THESE THREE NEGATIVE-PROJECTING CONDUITS, AND THE COMPARISONS SHOWN BETWEEN THE MAXIMUM WEIGHED LOADS AND THOSE CALCULATED WITH THE SPANGLER FORMULA. THE COMPARISON OF CALCULATED LOADS AND THESE MEASURED LOADS DEMONSTRATE THE EFFECTIVENESS OF NEGATIVE-PROJECTION LOADING AS A MEANS OF DECREASING THE LOAD ON CULVERTS TO BE INSTALLED UNDER HIGH FILLS. THE CLOSE CORRELATION BETWEEN CALCULATED AND WEIGHED LOADS PROVIDES ADDITIONAL CONFIRMATION OF THE MARSTON FILL-LOAD THEORY.