PLAXIS 3D Moving Load Function

Question

Hi all, 
 May I ask a question regarding the theory behind the moving loads function in PLAXIS 3D? 
 I understand that users can assignment Movement to point loads with a linear, harmonic or table based signal specifying an initial velocity, acceleration, or variation of the velocity through time. But, is there any underlying theory behind this logic? 
 Thanks!

Stefanos Papavasileiou · Answer

Dear Chua Shin Ying, 
 The underlying theory is the same as in any calculation that involves Dynamics. The moving load is the feature implemented in PLAXIS to support the simulation of any dynamic load that follows a movement function. 
 Detailed information about this feature can be found in our Reference manual. 
 Also, take a moment to check our video presenting the feature below: https://communities.bentley.com/products/geotechnical1/w/wiki/45897/how-to-model-moving-loads-for-dynamic-calculations

Stefanos Papavasileiou · Answer

Dear Chua Shin Ying, 
 1) The moving loads allow adding a movement function with a direction to multiple points. Those points will share the same movement function, which can be selected in the GUI. This is demonstrated in the video I recommended to check in my previous answer. Note that this is not the same as assigning a multiplier to a single load as in this case there is no movement defined, which is the case for instance when modelling a train passing the tracks. 
 2) In PLAXIS, the Newmark&rsquo;s time integration scheme is used to solve the dynamic equilibrium of the system (i.e. time-dependent movement of a body subjected to dynamic loading). For further details, please refer to Chapter 5 of the Scientific manual. Similar to what is considered for static equilibrium, the problem is formulated within the framework of continuum mechanics and solved using Finite Element Method.