Shell model for tsunami load

[crisjaqueplaza]

Hi,

I would like to know whether the model attached to this message (confined masonry walls modeled using a macromodeling approach) is suitable for tsunami loads in a dynamic analysis, specifically regarding out-of-plane behavior. In particular, I have some doubts related to the following points:

1) Is ASDConcrete3D a suitable material for this purpose?

2) Do I need to use a PlateFiber material? As shown in my model, I am currently using PlaneStress + PlateFromPlaneStress, which results in linear out-of-plane behavior. Is this acceptable for this type of analysis? I am not completely clear on this point because I want to consider out-of-plane behavior in both masonry panel and RC beams/columns.

3) Which element is more suitable for this type of analysis: ASDShellQ4 or ShellMITC4?

4) What is the difference between using PlaneStress + PlateFromPlaneStress versus using PlateFiber directly in the layered shell section?

Thank you very much in advance. Clarifying the suitability of my model for this type of loading is very important for my work.

[STKO Team]

1) Is ASDConcrete3D a suitable material for this purpose?

Yes, it's a full 3D nonlinear material for concrete

2) Do I need to use a PlateFiber material? As shown in my model, I am currently using PlaneStress + PlateFromPlaneStress, which results in linear out-of-plane behavior. Is this acceptable for this type of analysis? I am not completely clear on this point because I want to consider out-of-plane behavior in both masonry panel and RC beams/columns.

Converting the ASDConcrete3D (full 3D) to PlaneStress (2D in-plane, S33=S13=S23=0), and then converting it to PlateFiber (only S33=0) via PlateFromPlaneStress, results in a material with nonlinear membrane behavior, nonlinear bending behavior, but LINEAR TRANSVERSE SHEAR. Suitable for thin shells.
We typically use it ONLY if the RC wall has significant transverse shear reinforcement, but a shell section can only represent bending reinforcements. In those cases we don't want the transverse shear failure governed by only the low concrete strength.
In all other cases we just use the ASDConcrete3D (no need to plug it into a PlateFiber, it's done automatically by ASDConcrete3D)

3) Which element is more suitable for this type of analysis: ASDShellQ4 or ShellMITC4?

ASDShellQ4 is much more accurate for the in-plane behavior. For the out-of-plane they both use the MITC (Mixed Interpolation of Tensorial Components) formulation.

[crisjaqueplaza]

Regarding on this topic, I want to clarify that my structure is modelled with the macromodeling approach (bricks and mortar as a homogeneuos material). So, I want to ask you: do I need to reduce the transversal shear stress with respect of the in-plane shear stress (by means of using ortrothopic material) to incorporate the weakness of the masonry panel in the out-of-plane direction?

I know that this is a direct question, but honestly I was searching in some papers about this and I couldn't find some relevant information to conclude in a proper way.

Thanks in advance!

[STKO Team]

I think you can safely use the same shear strength as the one used for the in-plane behavior.

When you choose the homogeneous approach, you make several simplifications. Already in the in-plane direction, you are not distinguishing whether the shear strength is due to sliding or diagonal failure, and the same applies to the OOP shear behavior. Therefore, I do not think it is worth using an orthotropic wrapper just to reduce it.

However, if you have experimental evidence showing that this reduction is significant for your type of masonry, then you can apply it.