<
From version < 24.1 >
edited by Hamid Richard Allili
on 2019/11/26 14:24
To version < 25.1 >
edited by Hamid Richard Allili
on 2019/11/26 14:30
>
Change comment: There is no comment for this version

Summary

Details

Page properties
Content
... ... @@ -86,32 +86,10 @@
86 86  
87 87  In this case, only mechanical properties are needed for a library element (as there is no design for them), and these values should be manually defined by the User.
88 88  
89 -= Analysis and results =
89 += Results =
90 90  
91 -Analysis of laminated type shell structures become available by a new mechanical model implemented into FEM-Design, based on the laminated shell theory. From civil engineering point of view, the most popular field of application is the cross laminated timber (CLT) panel, although the theory in itself is more general, it is applicable for any kind of laminated composite surface structure. As the main purpose of this feature is to calculate and design CLT panels, the currently existing Timber plate and Timber wall tools are supplemented with this calculation model.
91 +Models containing CLT/GLC panels offer both model space and detailed analysis results for load case, load combination, maximum of load combination, maximum of load groups, influence line and moving load maximum results. The first group contains the displacements, internal forces and stresses, where the former two are displayed in the same way as for the existing non-laminated shells, while the stresses need some further options due to the laminated structure of these shells. A layer in which we would like to see the top/center/bottom stresses and a coordinate system also need to be selected the plot the well-known stress result types. As the shell itself has a local system and all layers in the shell have a local system, the understanding of the stress components is not obvious, therefore the coordinate system is also an option it can be either "Shell local system" or "Layer local system". For example, the physical direction of a displayed Sigma x' stress varies according to the selected system, if shell and layer local system is not identical, which means the angle Theta defined in the library for the layer is not zero.
92 92  
93 -[[image:1574678804425-887.png]]
94 -
95 -Although, the theory used for the calculation of displacements and stresses is general, the application data (e.g. deformation factor, service class, etc.) and design methods for CLT panels are very specific and standard dependent. In order to preserve the possibility of general application, two new options are added to the original mechanical model used for the calculation of timber shell structures (Orthotropic shell): Cross laminated timber and General laminated composite (GLC).
96 -
97 -For CLT panels, both analysis results (displacements and stresses) and design calculations are available, while for GLC panels only the first one is provided. These panel types are stored in different libraries, but their definition is very similar, we can define them layer by layer. In case of CLT, adding a new layer is possible by clicking on the material cell of the table, by this the original timber material library pops up, where we can select the constituent material of the current layer. After the selection, the program automatically fills all necessary data of the current layer, including mechanical properties (for analysis results) and limit stresses (for design calculations).
98 -
99 -[[image:1574689871786-555.png]]
100 -
101 -It is very important that among the required layer data, there are some properties not specified by the Eurocode, these can be assumed based on the existing ones according to the following (in case the manufacturer does not specify different values for them):
102 -
103 -• G,,yz,, (G,,rolling,,) = G,,mean,, / 10
104 -
105 -• nu,,xy,, = 0.2
106 -
107 -• f,,Rk,, = f,,vk,, / 2
108 -
109 -• f,,xyk,, = f,,vk,,
110 -
111 -Of course, every value can be overwritten by demand. Besides the layers, the default deformation factors by service classes and stiffness reduction factors also need to be specified for a CLT library element. The new cross laminated timber library is filled up with the products of many famous manufacturers by default, new elements can be easily created based on them. The definition of GLC library elements is very similar, except that only the mechanical properties are necessary to define. For all the three mechanical type a display stiffness option is available to see the element stiffness matrix (refer to mid-plane) of the panels used in the calculations (and/or check its singularity), including the "B" submatrix responsible for the coupling effect.
112 -
113 -Models containing CLT/GLC panels offering both model space and detailed analysis results for load case, load combination, maximum of load combination, maximum of load groups, influence line and moving load maximum results. The first group contains the displacements, internal forces and stresses, where the former two are displayed in the same way as for the existing non-laminated shells, while the stresses need some further options due to the laminated structure of these shells. A layer in which we would like to see the top/center/bottom stresses and a coordinate system also need to be selected the plot the well-known stress result types. As the shell itself has a local system and all layers in the shell have a local system, the understanding of the stress components is not obvious, therefore the coordinate system is also an option it can be either "Shell local system" or "Layer local system". For example, the physical direction of a displayed Sigma x' stress varies according to the selected system, if shell and layer local system is not identical, which means the angle Theta defined in the library for the layer is not zero.
114 -
115 115  [[image:1574690365292-190.png||height="397" width="922"]]
116 116  
117 117  It is worth to mention that in contrary with the non-laminated shells, the transverse shear stresses (Tau y'z' and Tau x'z') can be also displayed at the top and bottom of layers besides the center, as in case of some intermediate layer they are not necessarily zero (for non-laminated shells, due to the parabolic stress distribution the top and bottom values are always zero, only the center value can be selected from the shell stresses list). Due to the numerous options, finding maximum stresses by components on the shell can be quite time consuming, especially in case of the complex loading of the structure. In order to overcome this difficulty and make the maximum finding process way easier, besides the point based detailed result (e.g. for RC shells, Footfall calculation) a shell based option is also implemented. At the first option we can select an arbitrary point on the CLT/GLC panel, in the detailed result the geometry of the shell and the five stress components are displayed. As the whole section of the shell can be seen here, the coordinate system selector is supplemented with each layer's local system options. In case of maximum result (maximum of load combinations, etc.) plenty of maximum criteria available, which can be grouped by the following:
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