https://forums.autodesk.com/t5/structural-bridge-design-forum/horizontal-reactions/m-p/10395189#M1265 <P>Hi Sonya,</P><P>These are real effects with the supports arranged as they are as there are local redundancies .&nbsp; For example, in your model you have each support at the second pier fixed in the x direction, which will restrain any longitudinal movement across the deck section at this pier.&nbsp; If the applied load was a simple point load on the mid point of the edge girder in span 2 then you would expect the deck to deform in torsion, transverse bending and longitudinal bending such that&nbsp; the plane section would not remain plane across the whole deck.&nbsp; If the supports are fixed in dx then you will see a reaction at each of these - but the total shouls equal zero if no external horizontal load is applied.</P><P>&nbsp;</P><P>If you reduce your supports so that only rigid body motion is restrained, then you would see this effect in the deflected shape. I suggest that all supports are fixed vertically; support 1202 is fixed dx,dy,dz; and support 1938 is fixed dy,dz.&nbsp; This will provide the minimum supports to resist rigid body motion without introducing any additional local redundancy.</P><P>&nbsp;</P><P>I hope this helps but please let me know how you get on.&nbsp; If this has solved your problem then please mark my reply as a solution so that others may benefit.</P><P>&nbsp;</P><P>Kind regards</P><P>&nbsp;</P><P>Dave Geeves</P> Wed, 16 Jun 2021 14:55:18 GMT dave_geeves 2021-06-16T14:55:18Z https://forums.autodesk.com/t5/structural-bridge-design-forum/horizontal-reactions/m-p/10395023#M1264 <P>Hi,</P><P>&nbsp;</P><P>I am assessing a continuous three-span steel/concrete composite bridge deck.</P><P>&nbsp;</P><P>The deck has been modelled using a 3D shell finite element slab with the main steel composite beams inserted as FE web beams. Cross girders, concrete upstands and diaphragms have been added as beam members.</P><P>&nbsp;</P><P>There are only vertical loads applied to the deck model. However, I am getting horizontal reactions at the fixed support, which I didn't expect, as there are no horizontal loads. Could you please advise why these horizontal reactions appear?</P><P>&nbsp;</P><P>Thanks,</P><P>&nbsp;</P><P>Sonia</P> Wed, 16 Jun 2021 13:53:12 GMT https://forums.autodesk.com/t5/structural-bridge-design-forum/horizontal-reactions/m-p/10395023#M1264 Anonymous 2021-06-16T13:53:12Z https://forums.autodesk.com/t5/structural-bridge-design-forum/horizontal-reactions/m-p/10395189#M1265 <P>Hi Sonya,</P><P>These are real effects with the supports arranged as they are as there are local redundancies .&nbsp; For example, in your model you have each support at the second pier fixed in the x direction, which will restrain any longitudinal movement across the deck section at this pier.&nbsp; If the applied load was a simple point load on the mid point of the edge girder in span 2 then you would expect the deck to deform in torsion, transverse bending and longitudinal bending such that&nbsp; the plane section would not remain plane across the whole deck.&nbsp; If the supports are fixed in dx then you will see a reaction at each of these - but the total shouls equal zero if no external horizontal load is applied.</P><P>&nbsp;</P><P>If you reduce your supports so that only rigid body motion is restrained, then you would see this effect in the deflected shape. I suggest that all supports are fixed vertically; support 1202 is fixed dx,dy,dz; and support 1938 is fixed dy,dz.&nbsp; This will provide the minimum supports to resist rigid body motion without introducing any additional local redundancy.</P><P>&nbsp;</P><P>I hope this helps but please let me know how you get on.&nbsp; If this has solved your problem then please mark my reply as a solution so that others may benefit.</P><P>&nbsp;</P><P>Kind regards</P><P>&nbsp;</P><P>Dave Geeves</P> Wed, 16 Jun 2021 14:55:18 GMT https://forums.autodesk.com/t5/structural-bridge-design-forum/horizontal-reactions/m-p/10395189#M1265 dave_geeves 2021-06-16T14:55:18Z