Now, I need to calculate the section capacity of this shear wall.
For shear, the shear capacity is sum of 2 parts of piers.
However, for moment, it is not like that. If I consider it is as a gross section of pier, the moment capacity is high, but if I consider there are 2 sections of piers, the moment capacity is lower much. The real moment capacity is somewhere in between because of the spandrel.
Anyone has way to calculate the moment capacity of this shear wall accurately? Please help me!
Thanks!
Hi Linh,
I am not clear what you are trying to achieve here. It seems you are using an FEA - then why you need flexural rigidity...? On the other hand, your question relates to manual calculation checks - then obviously it is essential to have all properties in hand.
So, please clarify what exactly you are doing. Meanwhile, I will assume that your study does not involve FEA and my thoughts will be tied up with first principles.
Engineering judgement needs be applied here... For the height-to-width ratio indicated on your sketch, the stiffness of a single spandrel is almost second to none comparing with the stiffness of two isolated wall panels. Therefore, while some stiffening effect is offered by the spandrel, considering of two discrete walls without rigid connection through the spandrel is reasonable and may be slightly more conservative.
I.e. the stiffness of the spandrel is not sufficient to mobilise the two separate wall panels to act integrally (compositely).
If the wall stacks up to achieve much higher height-to-width ratio (multi multi storey building) and there are few more spandrels, then the composite action will/may integrate the two "branches" into a single unit with increased stiffness. This will also compensate for the increase of lateral flexibility of taller structure.
I hope my deliberation clarifies...
Regards,
R
Hi Ruslan,
Thanks for your response,
Yes, I would like to make the hand calculation based on the section, material, reinforcement, axial force which are known of shear wall to check their capacity (moment capacity).
In this case, there are also have few more coupling beams. But I think the stiffness of spandrel and coupling beams are not enough to make these 2 piers into a single shear wall. But the stiffness of spandrel and coupling beam can not be neglected to check only 2 piers separately.
My problem is how to check their capacity by hand but still consider the real stiffness of coupling beams and spandrel.
Best Regards,
Linh
Have you done a composite beam design? I.e. concrete slab and steel beam connected with shear studs. Studs can be under-designed so that the composite stiffness of the beam is reduced.
As an analogy, your problem is slightly similar to the above.
I.e. check vertical shear transfer through the spandrel and check whether the spandrel provides 100% shear transfer or less. This will give the coefficient, say 0.5 to 1.0, etc.
Then find the I-value for the two walls combined in one and multiply it by that coefficient. It is obviously an approximation, but closer to realistic solution.
I hope it clarifies at least a bit.
Regards,
R
I have not designed any composite component before.
Same as you, I thought about multiplying by a coefficient to get an approximately solution but how much I should take? What can affect this coefficient? Do you know any paper relating to this?
Thank you,
Best Regards,
Linh
Try to limit the applied load to the second pier to axial capacity of the spandrel beam, since this is the maximum load that can pass from one pier to the other.
Regards
SO
Try attached shear wall design guides.
Composite action between two elements is almost universal as of use of first principles, i.e. two timber plates, steel and concrete sections or two concrete walls. all working in flexure, will all produce longitudinal shear taken by ether shear studs, nails or spandrel beams. This is also called coupling.
So, don't be bogged down by composite design, this was just an analogy.
Regards,
R
Hi, the easiest way how to calculate this problem is using the strut and tie models. The most accuracy is achieved by using the nonlinear FEA method. With linear FEA analysis are the results with great errors because of nonlinearity of stress and strain.
Hi Linh,
It seems this system similar to a concrete frame. Thus, In first step use compression and tension method (C & T method). Left wall look like a big column under tension and right wall is similar to a huge column under compression. The key point for design and analysis of this structure is about linked beam between two wall. It' better that use a beam with big wide, because value of shear force is very more and of course the length of this beam is very less, so the stiffness is very high and load absorption in very more. Finally, we should design with high accuracy for safety structure and construction.
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