welding in simulation express

Hello every one, 

First of all, I hope my english is good enough to be understood. 

I'm working on solidworks  Professional 2016 with the simulation Express Tool. 

I'm doing a basic simulation with one face locked down  and one on whiche a strengh is applyied, It look likes the weldings I put on my part are not integrated inside the simulation calculus. 

In fact, I did a first simulation without weding my part, and a second one with some welding. 

The only difference between my 2 parts / simulation parameters are those weldings. 

The results of my simulations are the same with or with with out the welding. 

attached to my post is the part I'm working on. 

Can the welding be integrated to the simulation with the simulation express tool ? 

If yes (and I hope it's possible), Can someone explain me how to do it ? 

Looking forward to your early reply, 

BR 

SolidworksSimulation