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Highway Bridge Loads and Load Distribution

Highway Bridge Loads and Load Distribution 6.1 6.2 6.3 Introduction Permanent Loads Vehicular Live Loads Design Vehicular Live Load • Permit Vehicles • Fatigue Loads • Load Distribution for Superstructure Design • Load Distribution for Substructure Design • Multiple Presence of Live-Load Lanes • Dynamic Load Allowance • Horizontal Loads Due to Vehicular Traffic Susan E. Hida California Department of Transportation 6.4 6.5 6.6 6.7 Pedestrian Loads Wind Loads Effects Due to Superimposed Deformations Exceptions to Code-Specified Design Loads 6.1 Introduction This chapter deals with highway bridge loads and load distribution as specified in the AASHTO Load and Resistance Factor Design (LRFD) Specifications [1]. Stream flow, ice loads,. | Hida S.E. Highway Bridge Loads and Load Distribution. Bridge Engineering Handbook. Ed. Wai-Fah Chen and Lian Duan Boca Raton CRC Press 2000 6 Highway Bridge Loads and Load Distribution 6.1 Introduction Susan E. Hida California Department of Transportation 6.2 Permanent Loads 6.3 Vehicular Live Loads Design Vehicular Live Load Permit Vehicles Fatigue Loads Load Distribution for Superstructure Design Load Distribution for Substructure Design Multiple Presence of Live-Load Lanes Dynamic Load Allowance Horizontal Loads Due to Vehicular Traffic 6.4 Pedestrian Loads 6.5 Wind Loads 6.6 Effects Due to Superimposed Deformations 6.7 Exceptions to Code-Specified Design Loads 6.1 Introduction This chapter deals with highway bridge loads and load distribution as specified in the AASHTO Load and Resistance Factor Design LRFD Specifications 1 . Stream flow ice loads vessel collision loads loads for barrier design loads for anchored and mechanically stabilized walls seismic forces and loads due to soil-structure interaction will be addressed in subsequent chapters. Load combinations are discussed in Chapter 5. When proceeding from one component to another in bridge design the controlling load and the controlling factored load combination will change. For example permit vehicles factored and combined for one load group may control girder design for bending in one location. The standard design vehicular live load factored and combined for a different load group may control girder design for shear in another location. Still other loads such as those due to seismic events may control column and footing design. Note that in this chapter superstructure refers to the deck beams or truss elements and any other appurtenances above the bridge soffit. Substructure refers to those components that support loads from the superstructure and transfer load to the ground such as bent caps columns pier walls footings piles pile extensions and caissons. Longitudinal refers to the axis parallel to the