1. Live Load Effect in Reinforced Concrete Box Culverts Under Soil Fill Sarah Orton, Erik Loehr, Andrew Boeckmann, and Garrett Havens University of Missouri 1

2. Research Motivation 2  Load Rating required for all bridge size culverts (span > 20ft)  In the case of culverts under deep fill, effect of dead load much greater than live load – negligible live load effect  Missouri has approximately 3000 culverts. About 700 (23%) have fill depths greater than 6 ft.  Impact – significant reduction in number of man hours required to load rate culverts and reduction of unnecessary load posting of culverts

3. Research Methodology 3  10 culverts were selected for testing  Culverts ranged in fill depth from 2.5 feet to 13.5 feet  Determine the fill depth which Live Load becomes negligible  Live Load utilized a Dump Truck loaded and parked at specific locations to maximize strains  Effects of loadings were recorded via strain transducers, and an accelerometer attached to the underside of the culverts

4. Research Methodology 4  Tests were conducted in Two Rounds.  Five culverts with similar geometrics but varying fill heights made up first round  Second round focused on various cell sizes, arrangements and design loads at depths near where live loads become negligible during the first round  Computer models of each culvert were created to fully analyze the results

5. Culverts  10 culverts with fill depths from 2.55 ft to 13.25 ft were tested  Culverts were built between 1954 and 2001  Design Load H10 and H15 5 Bridge #CountyRoute Cell Size Year Built Design Load Design Fill Actual Fill Clear Height Slab Thickness Wall Thickness Skew Phase 1 Culverts L0525CallawayRT F E2x12'1953H 152.582.759.51111.50 N0936PettisRT J S2x12'1960H 1545.07.510.580 A2869MaconMO 3 S2x11'1972H 1566.488119.50 R0015BooneRT NN2x13'1962H 157.88.159.7513.59.515 P0622CallawayRT O E2x12'1954H 1011.5113.251015.51015 Phase 2 Culverts A6330AudrainRT AA3x142001 32.547811815 N0793MontgomeryRT J S2x141962 1.822.5557.5108.50 N0502MontgomeryMO 943x151958 3.824.491610.5810 X0749BooneRT O S2x121947H 105.116.35101290 N0059GasconadeRT Y E2x101957H 106.18.258117.510

6. Instrumentation  Each culvert was instrumented with 12 strain transducers, 11 LVDTs, and one accelerometer to capture maximum strains and displacements as truck moved over culvert 6 Phase 1 Phase II

7. Live Loading  Truck loaded to approximately 50 kips was positioned in 7 static positions above the culvert to induce maximum strains and displacements in gages Position 1 Centered over secondary span Position 2 Rear tire in middle of secondary span Position 3 Centered middle wall Position 4 Front rear tire middle primary span Position 5 Centered over primary span Position 6 Rear tire in middle of primary span Position 7 Centered over far wall 7

8. Results from data - Strains  Maximum strain measured in top slab vs fill depth 8 1.0 E-05 ~ 40 psi

9. Results from data - LVDT  Maximum displacement vs fill depth 9

10. Conclusions  Culvert testing was successful and reasonable trends found in both strain and displacement data  Culvert design is very conservative, especially at shallower fill depths  A possible point for cutoff of load rating is around 6 ft. 10

11. Future Research 11  NCHRP Study selected to evaluate Live Load Impact on Culverts  Expand study to other states?  Reduce need for load rating in deep fill culverts  Improve load rating procedures  Reduce over-conservatism in design of culverts by better understanding load distribution through soil and pavement