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Causes of Bumps at Pavement-Bridge Interface

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Presentation on theme: "Causes of Bumps at Pavement-Bridge Interface"— 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 Presenter: Amar Shukla Youngstown State University

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

4 Youngstown State University
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

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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 bumps Bridges with bumps COL COL COL L COL COL Liquid Limit 34.1 21.5 24.9 33.6 32.2 Plastic Limit 24.5 25.5 21.9 30.7 38.4 Plasticity Index 9.6 NP 3.4 2.9 AASHTO Soil Classification A-2-4 (0) A-3 (0) A-1-b (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
Lmin (ft) h (in) fc‘ (ksi) As (in2/ft) As’ d‘ Cc Φ Mn (k*ft/ft) Mu AZ 15 12 3 1.053 0.133 2.5 37.57 9.77 FL* 30 4.5 0.310 4 32.57 80.03 IN 20 10 0.630 0.203 2 19.14 30.16 KY 25 17 3.5 1.58 90.10 61.72 MI* 0.895 21.87 31.72 OH 2.345 0.207 129.81 90.4 PA 16 1.693 0.31 85.22 60.5 Youngstown State University

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

12 Youngstown State University
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
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14 Model without soil underneath
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15 Analytical Simulation Results
Soil underneath slab: Deflection = in. Maximum Beam Stress = lb/in2. Soil moved out Deflection = in. Maximum Beam Stress = lb/in2. Youngstown State University

16 Approach Slab Model under HL-93 with soil underneath
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17 Approach Slab Model under HL-93 without soil underneath
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18 Recommendations for Ohio Approach Slab
ΦMn calculated by using ODOT specs. = kip-ft. Mu calculated by using ALGOR values = kip-ft. Design of approach slab L = 30 ft. B = 20 ft. Bottom reinforcement = 5.5 in c.c Top reinforcement = 18 in c.c. Youngstown State University

19 Youngstown State University
References American Association of State Highway and Transportation Officials, LRFD Bridge Design Specifications, 4th 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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