In India, some bridge engineers have doubts on point of application of horizontal load. Some people consider the point of application of longitudinal and transverse load at the bearing level.
Longitudinal force :
The longitudinal forces shall be considered as acting horizontally through the knuckle pins in case of bearings having rocking arrangement or through girder seats in case of sliding, elastomeric, or PTFE bearings for the design of bearings and substructure.
The force is to be applied at the top of the bearings for the earthquake in the longitudinal direction.
Point of application
at the level of bearing (Ref. cl. 2.8.2.3 of IRS Bridge Rule & Clause 219.5, Annexure D of IRC: 6-2016).
Transverse force :
The horizontal force is required to be applied at the center of mass of the superstructure horizontal deflection at the top of the pier/ abutment for the earthquake in the transverse direction.
Point of application:
The center of mass of the superstructure (Ref. cl. 2.8.2.3 of IRS Bridge Rule & Clause 219.5, Annexure D of IRC: 6-2016)