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Causes of Bumps at Pavement- Bridge Interface AKM Anwarul Islam, Ph.D., P.E. Associate Professor Youngstown State University Amar Shukla Graduate Student.

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Presentation on theme: "Causes of Bumps at Pavement- Bridge Interface AKM Anwarul Islam, Ph.D., P.E. Associate Professor Youngstown State University Amar Shukla Graduate Student."— Presentation transcript:

1 Causes of Bumps at Pavement- Bridge Interface AKM Anwarul Islam, Ph.D., P.E. Associate Professor Youngstown State University Amar Shukla Graduate Student Youngstown State University Presenter: Amar Shukla Youngstown State University

2 Definition of Bumps Differential settlement of bridge and approach slab and/or approach slab and pavement Approach slabs are provided for smooth transition of vehicles Briaud et al. (1997) summarized that 25% of total bridges in the USA had bridge bumps that cost almost $100 million per year for repair Youngstown State University

3 Behavior of approach slab due to pavement settlement and bump mechanism Youngstown State University

4 Goals of Research Cost-effective solution to the existing problems of the bumps Reduce safety hazards and maintenance cost Smoother ride to drivers Youngstown State University

5 Causes of Bumps Movement of soil beneath slab Strength deficient approach slabs Continual impact of vehicles running over already compacted area Insufficient compaction of soil especially of the embankment backfill Types of soil Youngstown State University

6 Causes of Bumps (contd.) Short-term and long-term settlement Bridge-end conditions Construction methods, roadway paving and bridge/roadway joint Water seepage Traffic volume Youngstown State University

7 Experimental Investigations 2 bridges with bumps and 3 bridges without bumps were visited Atterberg Tests (Liquid Limit and Plastic Limit) and Sieve Analysis tests were conducted Soil samples were collected from the surface Youngstown State University

8 Experimental Investigations (contd.) Results on Bridges without bumpsBridges with bumps COL 30 2578COL 30 2667COL 30 11 2LCOL 30 2670COL 30 3182 Liquid Limit 34.121.524.933.632.2 Plastic Limit 24.525.521.930.738.4 Plasticity Index 9.6NP3.42.9NP AASHTO Soil Classification A-2-4 (0)A-3 (0)A-1-b (0) A-3 (0) Youngstown State University

9 Experimental Investigations (contd.) Soil is granular Various methods through which proper compaction of granular soil can be obtained: Pneumatic rubber-tired rollers Vibratory rollers Handheld vibrating plates Youngstown State University

10 Approach slab designs in state DOTs StateL min (ft) h (in) f c (ksi) A s (in 2 /ft) A s (in 2 /ft) d (in) C c (in) Φ M n (k*ft/ft) M u (k*ft/ft) AZ151231.0530.1332.5337.579.77 FL*30124.51.0530.3102.5432.5780.03 IN201040.6300.2032.5219.1430.16 KY25173.51.5800390.1061.72 MI*20124.50.895 3321.8731.72 OH30174.52.3450.20733129.8190.4 PA25163.51.6930.312.5385.2260.5 Youngstown State University

11 Geometric Parameters Approach slab of L = 30 ft. and B = 20 ft. Bottom Steel:#10 reinforcing bars @ 6.5 in. c.c. Top Steel:#5 reinforcing bars @ 18 in. c.c. Bent Steel:#5 reinforcing bars @18 in. c.c. Vertical Steel:#5 reinforcing bars @ 6 in. c.c. Youngstown State University

12 Model Parameters Surface to surface contact b/w approach slab and sleeper slab Bonded contact b/w approach slab and end bent HL-93 truck single lane loading conditions Model was built as a simple supported 2 models were built considering soil underneath and soil completely moved out Youngstown State University

13 Model with soil underneath Youngstown State University

14 Model without soil underneath Youngstown State University

15 Analytical Simulation Results Soil underneath slab: Deflection = 0.057 in. Maximum Beam Stress = 569.245 lb/in 2. Soil moved out Deflection = 0.179 in. Maximum Beam Stress = 3028.978 lb/in 2. Youngstown State University

16 Approach Slab Model under HL-93 with soil underneath Youngstown State University

17 Approach Slab Model under HL-93 without soil underneath Youngstown State University

18 Recommendations for Ohio Approach Slab ΦM n calculated by using ODOT specs. = 128.91 kip-ft. M u calculated by using ALGOR values = 139.95 kip-ft. Design of approach slab L = 30 ft.B = 20 ft. Bottom reinforcement = #10 @ 5.5 in c.c Top reinforcement = #5 @ 18 in c.c. Youngstown State University

19 References American Association of State Highway and Transportation Officials, LRFD Bridge Design Specifications, 4 th edition, 2007. Briaud, J. L., James, R. W., and Hoffman, S. B. (1997). NCHRP synthesis 234: Settlement of Bridge Approaches (the bump at the end of the bridge), Transportation Research Board, National Research Council, Washington, D.C., 75 pp. Cai, C.S., Voyiadjis, G.Z., and Shi, X. (2005). Determination of Interaction between Bridge Concrete Approach Slab and Embankment Settlement, Report No. FHWA/LA. 05/403, Louisiana Transportation Research Center, Louisiana Department of transportation, 152 pp. Youngstown State University

20 Causes of Bumps at Pavement- Bridge Interface Thank You! Any Questions? Youngstown State University


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