How to best define a mesh for the transmission of a wind load to facade nodes? - Grasshopper2024-03-28T23:52:27Zhttps://www.grasshopper3d.com/forum/topics/how-to-best-define-a-mesh-for-the-transmission-of-a-wind-load-to?groupUrl=karamba&commentId=2985220%3AComment%3A1920214&xg_source=activity&groupId=2985220%3AGroup%3A251211&feed=yes&xn_auth=noOk, everything makes sense no…tag:www.grasshopper3d.com,2018-07-14:2985220:Comment:19202142018-07-14T09:06:23.338ZNathan Stuckeyhttps://www.grasshopper3d.com/profile/NathanStuckey
<p>Ok, everything makes sense now!</p>
<p>Thank you Clemens, I really appreciate your feedback!</p>
<p></p>
<p>Ok, everything makes sense now!</p>
<p>Thank you Clemens, I really appreciate your feedback!</p>
<p></p> Hello Nathan,
there is an err…tag:www.grasshopper3d.com,2018-07-13:2985220:Comment:19199632018-07-13T19:16:35.614ZKaramba3Dhttps://www.grasshopper3d.com/profile/karamba
<p>Hello Nathan,</p>
<p>there is an error in the manual: the Z-component is perpendicular to the mesh in case of local mesh-loads.</p>
<p>Best,</p>
<p>Clemens</p>
<p></p>
<p>Hello Nathan,</p>
<p>there is an error in the manual: the Z-component is perpendicular to the mesh in case of local mesh-loads.</p>
<p>Best,</p>
<p>Clemens</p>
<p></p> I don't quite understand why,…tag:www.grasshopper3d.com,2018-07-13:2985220:Comment:19198612018-07-13T08:22:43.817ZNathan Stuckeyhttps://www.grasshopper3d.com/profile/NathanStuckey
<p>I don't quite understand why, but results become much more intuitive when I 'flip' the mesh and input a force vector oriented along the +z axis:…</p>
<p></p>
<p><a href="http://storage.ning.com/topology/rest/1.0/file/get/2769357909?profile=original" target="_self"><img class="align-full" src="http://storage.ning.com/topology/rest/1.0/file/get/2769357909?profile=RESIZE_1024x1024" width="671"></img></a></p>
<p><a href="http://storage.ning.com/topology/rest/1.0/file/get/2769358087?profile=original" target="_self"><img class="align-full" src="http://storage.ning.com/topology/rest/1.0/file/get/2769358087?profile=original" width="674"></img></a></p>
<p>I don't quite understand why, but results become much more intuitive when I 'flip' the mesh and input a force vector oriented along the +z axis:</p>
<p></p>
<p><a href="http://storage.ning.com/topology/rest/1.0/file/get/2769357909?profile=original" target="_self"><img width="671" src="http://storage.ning.com/topology/rest/1.0/file/get/2769357909?profile=RESIZE_1024x1024" width="671" class="align-full"/></a></p>
<p><a href="http://storage.ning.com/topology/rest/1.0/file/get/2769358087?profile=original" target="_self"><img src="http://storage.ning.com/topology/rest/1.0/file/get/2769358087?profile=original" width="674" class="align-full"/></a></p>
<p></p>
<p></p> Hi Clemens, thanks again,
I…tag:www.grasshopper3d.com,2018-07-13:2985220:Comment:19197682018-07-13T08:03:54.839ZNathan Stuckeyhttps://www.grasshopper3d.com/profile/NathanStuckey
<p>Hi Clemens, thanks again, </p>
<p></p>
<p>I feel silly for not understanding but I think the issue lies with a misunderstanding of how 'local to mesh' works. </p>
<p></p>
<p>Karamba Manual :</p>
<p>" 'local to mesh': X-component of the force vector is at right angle to the mesh-face</p>
<p>(...)</p>
<p>This means a surface load with components only in X-direction acts like wind pressure. "</p>
<p></p>
<p>The largest part of the facade mesh is parallel to the XZ plane.</p>
<p>Wind is…</p>
<p>Hi Clemens, thanks again, </p>
<p></p>
<p>I feel silly for not understanding but I think the issue lies with a misunderstanding of how 'local to mesh' works. </p>
<p></p>
<p>Karamba Manual :</p>
<p>" 'local to mesh': X-component of the force vector is at right angle to the mesh-face</p>
<p>(...)</p>
<p>This means a surface load with components only in X-direction acts like wind pressure. "</p>
<p></p>
<p>The largest part of the facade mesh is parallel to the XZ plane.</p>
<p>Wind is perpendicular to XZ plane. </p>
<p></p>
<p>So if I plug a force vector of (0.729,0,0) into the input of the mesh load set to 'local to mesh', in this case the y component of the resultant must be predominant? (IF the resultant vector is indeed expressed in the world coordinate system.)</p>
<p></p>
<p>Yet the mesh load says I've applied a load in the z direction, and I am now getting a resultant with null x and y components and 1089 kN in the positive vertical (z) direction...</p>
<p></p>
<p>It appears that either something is not behaving as it should or I am severely misinterpreting the behaviour!</p>
<p></p>
<p><a href="http://storage.ning.com/topology/rest/1.0/file/get/2769357581?profile=original" target="_self"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2769357581?profile=RESIZE_1024x1024" width="721" class="align-full"/></a></p>
<p><a href="http://storage.ning.com/topology/rest/1.0/file/get/2769357812?profile=original" target="_self"><img src="http://storage.ning.com/topology/rest/1.0/file/get/2769357812?profile=original" width="646" class="align-full"/></a></p>
<p><a href="http://storage.ning.com/topology/rest/1.0/file/get/2769359212?profile=original" target="_self"><img width="721" src="http://storage.ning.com/topology/rest/1.0/file/get/2769359212?profile=RESIZE_1024x1024" width="721" class="align-full"/></a></p>
<p></p>
<p>Apologies for taking up your time if this is basic/trivial for you!</p> Dear Nathan,
the option 'Loca…tag:www.grasshopper3d.com,2018-07-12:2985220:Comment:19193092018-07-12T18:20:11.882ZKaramba3Dhttps://www.grasshopper3d.com/profile/karamba
<p>Dear Nathan,</p>
<p>the option 'Local to mesh' lets you create a surface load which can be e.g. always perpendicular to the mesh faces - like wind compression or suction on a facade.</p>
<p>In the above case there are two wall pieces perpendicular to the y axis which do not have the same area. Therefore a resultant windload in Y-direction results.</p>
<p>Best,</p>
<p>Clemens</p>
<p></p>
<p>Dear Nathan,</p>
<p>the option 'Local to mesh' lets you create a surface load which can be e.g. always perpendicular to the mesh faces - like wind compression or suction on a facade.</p>
<p>In the above case there are two wall pieces perpendicular to the y axis which do not have the same area. Therefore a resultant windload in Y-direction results.</p>
<p>Best,</p>
<p>Clemens</p>
<p></p> Hello again Clemens,
Sorry…tag:www.grasshopper3d.com,2018-07-12:2985220:Comment:19196202018-07-12T16:07:14.255ZNathan Stuckeyhttps://www.grasshopper3d.com/profile/NathanStuckey
<p>Hello again Clemens,</p>
<p></p>
<p></p>
<p>Sorry to bother you again; I just wanted to verify that I've implemented your tips correctly.</p>
<p></p>
<p>1) You said to use a mesh which is finer than the underlying structural geometry. Here I use one which has been refined with a 5 level subdivision...does it appear ok to you or would you recommend going even smaller? Green nodes are the ones loads act upon.…</p>
<p></p>
<p></p>
<p>Hello again Clemens,</p>
<p></p>
<p></p>
<p>Sorry to bother you again; I just wanted to verify that I've implemented your tips correctly.</p>
<p></p>
<p>1) You said to use a mesh which is finer than the underlying structural geometry. Here I use one which has been refined with a 5 level subdivision...does it appear ok to you or would you recommend going even smaller? Green nodes are the ones loads act upon.</p>
<p></p>
<p><a href="https://storage.ning.com/topology/rest/1.0/file/get/2769357147?profile=original" target="_self"><img width="721" src="https://storage.ning.com/topology/rest/1.0/file/get/2769357147?profile=RESIZE_1024x1024" width="721" class="align-full"/></a></p>
<p></p>
<p>2) 'Local To Mesh' vs 'Global' vs 'Projected Global'</p>
<p></p>
<p>I am applying a positive wind pressure (0,729 kN/m2) in the direction of global positive y axis.</p>
<p>The façade mesh is 1505 m2, of which 1056 m2 runs parallel to the XZ plane.<br/>The wind pressure is 0,729 kN/m2 acting in the positive y direction ---> expected resultant of +/- 1056 x 0,729 = 770 kN.</p>
<p></p>
<p>'Global' gives +1098 kN in positive y direction.</p>
<p>'Global Projected' gives a +770 kN resultant in the positive y direction.</p>
<p>'Local to mesh'...gives -770kN along x axis (parallel to the façade according to ModelView) & -215kN along y axis. This surprised me since 'Local to mesh' is indeed the option to chose according to the manual yet I can't see how a wind load perpendicular to the facade would result in the tower moving in a cross-wind direction. 'Global projected' appears to provide the most logical result.</p>
<p></p>
<p>In view of these results, do you think the mesh remains ill-defined, the tower's shape is the culprit...or my choice of coordinate system for the load? What would you recommend? </p>
<p></p>
<p>Thanks again for your feedback, which is greatly appreciated.</p>
<p>Nathan</p>
<p></p>
<p></p> Hi Clemens,
Thank you very…tag:www.grasshopper3d.com,2018-07-12:2985220:Comment:19194932018-07-12T06:27:07.048ZNathan Stuckeyhttps://www.grasshopper3d.com/profile/NathanStuckey
<p>Hi Clemens, </p>
<p></p>
<p>Thank you very much, I'll try what you've suggested.</p>
<p></p>
<p>Nathan</p>
<p>Hi Clemens, </p>
<p></p>
<p>Thank you very much, I'll try what you've suggested.</p>
<p></p>
<p>Nathan</p> Hi Nathan,
extract the surfac…tag:www.grasshopper3d.com,2018-07-10:2985220:Comment:19195262018-07-10T18:14:58.748ZKaramba3Dhttps://www.grasshopper3d.com/profile/karamba
<p>Hi Nathan,</p>
<p>extract the surface where you want to apply the MeshLoad. In a second step you can use Grasshopper's built-in meshing components 'Mesh Surface' or 'Mesh Brep' or 'Mesh Breps' from Karamba3d.</p>
<p>Best,</p>
<p>Clemens</p>
<p></p>
<p>Hi Nathan,</p>
<p>extract the surface where you want to apply the MeshLoad. In a second step you can use Grasshopper's built-in meshing components 'Mesh Surface' or 'Mesh Brep' or 'Mesh Breps' from Karamba3d.</p>
<p>Best,</p>
<p>Clemens</p>
<p></p>