Load Distribution on Box Culverts

摘要

The report contains the results of field investigation of a functional, twin-cell, cast-in-place reinforced concrete box culvert in Sarpy County, Nebraska. Measurements were taken of soil pressures, concrete and steel strains, culvert deflection, and soil settlement. The effects of soil fill up to 12 feet high as well as AASHTO H-15 standard truck load were recorded. The vibrating wire technology was utilized extensively for pressure and strain measurements in order to obtain reliable long-term data for a period of 500 days. The details of construction, instrumentation and analysis of the culvert are given in the report. Generally, measured soil pressures due to soil loading confirm earlier analytical investigations that AASHTO-specified values may be too low, especially on side walls. Live load dispersion through soil was found to correlate reasonably well with theory and with the simple provisions of AASHTO. However, the report points out two factors not currently included in AASHTO which may further help distribute the effect of concentrated wheel loads: effect of rigid roadway pavement and effect of the 'two-way' action of the culvert top slab itself. As a byproduct of the investigation, a consistent cracking pattern in the wing walls had been observed in the test culvert and in others. This indicated the need for provision of a smoother transition between the barrel and the wing walls.