Highway Bridges: Analysis Technique & Design Procedure

1. United Arab Emirates University Graduation Projects Unit Highway Bridges: Analysis Technique & Design Procedure CEM2-1

2. Advisor: Dr. Bilal El-ArissCoordinator: Dr. Mousa HusseinExamination Committee:Dr. Mohamed ShakeelDr. AmrSweedanDr. KhaledElsawy Project Team Members

3. Acknowledgments Our sincere thanks and gratitude go to: • United Arab Emirates University (Graduation Projects Unit) • Dr. Bilal El-Ariss (Advisor) • Graduation Project Committee Members

4. Contents Introduction • Problem Statement • Project and Design Objectives • Project Scope Analysis and Design • Girder Design • Pier Cap Analysis and Design • Span Reconfiguration Alternative • Deck Analysis and Design • Girder Analysis Selection of Final Structural System Conclusion and Objectives Achieved

5. Problem Statement and Purpose • The purpose of this graduation project is to identify an existing structural engineering problem. • Develop an alternative analysis and design solution of a real-life existing structure; specifically Al-Sleimi Bridge.

6. Project and Design Objectives • The main objective of this project is to analyze and design a reinforced concrete girder bridge with 3 lanes on each roadway using AASHTO LRFD specifications. • The proposed design solution is to be considered as an alternative to the existing Al-Sleimi Bridge in Al Ain city.

7. Project Scope • The scope covers superstructure components, including: • Bridge Deck (Analysis/Design) • Longitudinal Girders (Analysis) • Longitudinal Girders (Design) • Pier Caps (Analysis/Design) • Span Reconfiguration (Analysis/Design) • Software: SAP2000 Software, Excel Sheets • Codes: AASHTO LRFD and ACI Specifications GP1 GP2

8. Sleimi Bridge Existing Specifications • # of Lanes: 3 lanes • Length: 50 m (3 spans) • Width: 10.5 m (each roadway) • Type: Rigid Frame • Median Width: 5 m • Completion Date: 1978 • Geographical Features: The bridge spans Al Sleimi Valley and is considered to be one of the main entrances by connecting Al Ain city to the northern emirates

9. Analysis/Design Process • The basic design expression in the AASHTO LRFD Bridge Specifications (2004) (AASHTO 1.3.2.1-1) that must be satisfied for all limit states is given as: Σ ηiγiQi ≤ φRn

10. Limit States Limit State: “The condition at which the member reaches its limiting capacity, and the structure fails to fulfill its intended function”. Two limit states were checked: • Strength Limit State: refers to providing adequate strength or resistance to satisfy the inequality of the previously mentioned equation for the statistically significant load combinations that a bridge is expected to experience in its design life (A1.3.2.4). • Service Limit State: refers to restrictions on stresses, deflections, and crack widths of bridge components that occur under regular service conditions (A1.3.2.2).

11. Strength (I) Load Combination, used for Flexural Resistance, is defined as: M (Strength 1) = γp DC + γp DW + 1.75 (LL + IM) where γp is equal to 1.25 (max.) for DC and 1.5 (max.) for DW. • Service I load combination, used for Control of Cracking, is defined as: Mservice1= ηi (1.0 MDC + 1.0 MDW + 1.0 MLL + IM) (AASHTO Table 3.4.1-1)

14. Corrections in GP1 Based on the graduation project committee’s comments along with our extensive reviews, corrections were made to erroneous calculations that had been previously performed in GP1: • Girder analysis section:girder dimensions, moment of inertia (I) corrections, and distribution factors for interior and exterior girders. • (DW) load: DW was taken into consideration for the span reconfiguration analysis/design. Other corrections were also made to the deck design process.

15. Girder Design Al-Sleimi Bridge

16. Girder Design • Girders are primary members that support the deck, positioned longitudinally along the traffic. • Girder analysis was performed in GP1, while girder design was completed in GP2 • Shear design was accounted for in the design of girders.

17. Bridge Dimensions (Superstructure) Isometric view of the proposed bridge

18. Total factored moment and shear load effects acting on the girders:

19. Design Theory Cross Sectional Dimensions Source: Reinforced Concrete Mechanics and Design, by James G. MacGregor and James K. Wight, fifth edition, Pearson Education, New Jersey, 2009, page 125, fig. 4-5.

20. Determine whether Case 1 or Case 2 for T Sections: Source: Dr. Tamer Maaddawy’sReinforced Concrete Design 1, Design of T-Sections lecture, slide 6

21. Design Steps for T-Section Girders: • Estimate concrete dimensions • Calculate Mu from applied loads • Calculate M(flange) • Compare M(flange) with Mu • Calculate steel ratio • Calculate area of steel • Ensure As > Asmin • Ensure tensile strain > 0.005 at failure • Draw the cross section Source: Dr. Tamer Maaddawy’sReinforced Concrete Design 1, Design of T-Sections lecture, slide 3

22. Design Equations Sample equations used in the design:

23. Girder Design (Interior Positive and Negative)

24. Girder Design (Exterior Positive and Negative)

25. Pier Analysis and Design

26. Pier Caps Analysis • Pier Cap: “The top beam in a bent which ties together the supporting columns or piles”. • Pier cap analysis consists of carrying out the analysis of both dead and live loads.

27. Pier Cap • A Pier Cap is located right on top of the piers where it can transmit the loads imposed on the bridge down to the substructure. • In contrast, piers are components that support the superstructure at intermediate locations between the end supports or abutments.

28. Pier Types • Selecting the most optimal pier type depends on site conditions, cost considerations, superstructure geometry, and aesthetics. • The most common pier types are single column (i.e., "hammerhead"), solid wall type, and bent type (multi-column or pile bent). • In this project, column bent and hammerhead piers were chosen.

29. Al Sleimi Bridge Current Design • Frame design is used in the current Al-Sleimi bridge in which the superstructure and substructure components are connected together to form one rigid structure. No pier caps are visible in this design.

30. Our Alternative Design(Column Bent Pier) In comparison, our design incorporates Column Bent Piers.

31. Dead Load Analysis(Own Weight of the Pile Cap) The dead load of the pile cap had been automatically calculated by SAP2000. However, the results have been consistent with the manual calculations.

32. Pier Cap Dead Load Analysis Process • Total Dead loads coming from girders were considered as point loads (concentrated loads on the pier cap). • In this case, there was a total of 11 concentrated loads imposed on the cap (since there are 11 girders). • The own weight of the cap was calculated as well (in the form of a distributed load).

33. Total Dead loads coming from girders were considered as point loads (concentrated loads on the pier cap).

34. SAP2000 • Created by Computers and Structures Inc., SAP2000 is a well-known structural engineering program that is used in the modeling and analysis of structures. • Such program was required to facilitate the analysis procedure

35. SAP2000 Dead Load Analysis Process • First, support reactions were determined from SAP2000 (Ex: Interior girders)

36. SAP2000 Dead Load Analysis Process • Next, reactions were entered as point concentrated loads (for both interior and exterior girders)

37. SAP2000Dead Load Analysis Process • Finally, shear forces and bending moments were determined for the maximum critical load effects

38. Pier CapLive Load Analysis

39. Selected Dimensions: b = 800 mm h = 1.2 m • Number of Design Lanes = W / 3600 mm Number of Design Lanes = 28920 / 3600 = 8 Lanes • Girder reactions for the lane and truck load were obtained next from SAP2000. Rtruck = 412.72 kNRlane = 192.47 kN • The value of the unfactored concentrated loads which represents the girder truck load reaction per wheel line was computed as: Pwheel = (Rtruck / 2) × (1 + IM) × (0.90) = 247.01 kN • Value of the unfactored uniformly distributed load : Wlane = (Rlane / 3 m) × (0.9) = 57.74 kN/m (No IM added)

40. Left to right lane load distribution of trucks

41. Entering lane load into SAP2000: Entering truck load into SAP2000

42. HL-93 Truck AASHTO (S.3.6.1.2)

43. The next step is to compute the reactions due to the above loads at each of the 11 bearing (support) locations • This is generally carried out by assuming the deck is pinned (i.e., discontinuous) at the interior girder locations but continuous over the exterior girders. Ʃ M = 0 & Ʃ Fy = 0. Example : • R1(ƩM = 0), R2 = (Ʃ Fy = 0), R1 = 402.6 kN

44. Pier Cap Load Analysis Process (Continued)

45. Once the reactions were obtained, their values were added to the live loads as shown: Total Loads for pier cap analysis:

46. The factored loads were then entered into SAP2000 to get the maximum factored moment and shear force effects (which depend on the values of the reactions), along with the distribution and number of columns. • In this case, the number of columns can be changed as needed: Factored loads entered into SAP2000:

47. Pier Cap Load Analysis Process (Continued) • 1st Iteration:

48. Pier Cap Load Analysis Process (Continued) • 2nd Iteration:

49. Pier Cap Load Analysis Process (Continued) • 3rd Iteration

50. Pier Cap Load Analysis Process • Final Results : Therefore , we are going to use the 3rd iteration’s values.