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# Types of Loads Considered for Design of Bridge Structures

Temporary bridges, such as Timber Bridge, are designed with this type of loading in mind. It is regarded as a light load. In the diagram below, both IRC classes A and B are depicted.Loads in IRC Classes A and B. Loads that have an impact the impact load on the bridge is created by rapid loads that occur when a vehicle travels across it. When the wheel is in motion, the live load is transferred from one wheel to the next, resulting in an impact load on the bridge. An impact factor is used to calculate impact loads on bridges. The impact factor is a multiplying factor that is affected by a variety of parameters such as vehicle weight, bridge span, vehicle velocity, and so on. The ramifications of many factors.

The wind load is also a significant consideration in bridge design. Wind load on short-span bridges can be insignificant. However, for medium-span bridges, wind loads should be taken into account while designing the substructure. Wind load is taken into account when designing superstructures for long span bridges. Wind Loads on Bridges are an issue that needs to be addressed. Longitudinal Forces, No Braking or accelerating a vehicle on the bridge causes longitudinal forces. When a vehicle comes to an abrupt stop or accelerates, longitudinal forces are applied to the bridge structure, particularly the substructure. As a result, the IRC advises that 20 percent of the live load be treated as longitudinal force on bridges. Bridge Longitudinal Forces centrifugal Forces if a bridge is to be built on horizontal curves, vehicle movement along the curves must be considered.

The buoyancy impact is taken into account for huge bridge substructures submerged in deep water. If the depth of submersion is low, the effect may be insignificant. Water Current Forces When constructing a bridge across a river, a portion of the foundation will be submerged in water. Horizontal forces are induced by the water movement on the submerged section. Water current forces are greatest at the top of the water level and zero at the bottom of the water level, or at the bed level. The temperature causes thermal strains. Extremely high or low temperatures cause stresses in bridge elements, particularly around bearings and deck joints. Because these stresses are tensile in nature, concrete will not be able to bear them.

Additional steel reinforcement perpendicular to the primary reinforcement should be installed to resist this. There are also expansion joints available. Bridge Thermal Stresses Seismic Loads When constructing a bridge in a seismic zone or earthquake zone, earthquake loads must be taken into account. During an earthquake, they produce both vertical and horizontal stresses. The amount of force applied is mostly determined by the structure’s self-weight. Larger forces will be exerted if the structure’s weight is greater. Bridge Structure Seismic Loads Horizontal and Deformation Effects Changes in material characteristics, either internally or externally, cause deformation stresses. Creep, concrete shrinkage, and similar horizontal forces will emerge as a result of temperature changes, vehicle brakes, earthquakes, and so on.

HA loads are loads that are evenly distributed across the bridge deck. These types of loads on bridges must be taken into account, and they are an important factor in the design. The HA loads that must be applied are determined by the bridge’s span. The uniformly distributed load can be evaluated using the procedure below. When the bridge span is smaller than 30 metres, the UDL is 30 kN per metre length per notional lane. The load can be computed using the equation when the loaded length reaches 30m, although it should not be less than 9 kN/mm2. The loaded length is L in this case.

## Different Settlement

However, because of the variations in loads and ground conditions, there is a risk of varied settlements when there are shallow foundations. Erection Loads The type of the building has a big impact on the loads that need to be considered for erection. Furthermore, the construction sequence is an important issue to consider during the design process.In addition, BS 5400 Part 2 Cl 5.9 should be consulted for more details. Buoyancy There will be buoyant force on the structure if the water table is above the foundation or any component of the construction. It must be considered during the design process because it may have a substantial impact on the structure’s design.

What are the three types of loads that determines the type of bridge?