Structural Instability & Zero Stiffness: Part 2 – Instability condition and rectification of model

Structural Instability and Zero Stiffness conditions are very common in a model, but if these problems are not rectified, that may lead to incorrect analysis and design result or complete failure of the structure.

In this video, I have discussed about instability condition, different types of instability, how to interpret the warning message and finally how to rectify the structure. Following is the concerned warning messages --

***WARNING - INSTABILITY AT JOINT 2 DIRECTION = MX
***NOTE - VERY WEAK SPRING ADDED FOR STABILITY

It is very crucial for structural integrity to understand the problem and accordingly rectify the problems - identification and rectification of instability problems will be covered in this video series.

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[rahuljain]

For the truss example of instability, where you assigned partial moments in truss members to remove instability, not only we released moments in truss members but we also let the members take shear in Z-direction, due to which static check is satisfied and instability is removed. Am i correct on this ? So, whenever we assign partial moment release, we not only allow minor moments to develop but we also allow full shear to develop on the truss members.. I hope i got it correctly.

[shaikzaheer]

Kindly make a video on all design parameters lx, ly, lz..etc as per is code and as well as American code...
Your videos are simply superb 👌 👏 👍 😍 🙌

[mojtabaosman]

Hi, I have a confusion about the beam/column displacement and deflection. IF the deflection (lateral displacement) check for a column (considering allowable L/400 for example) is pass using (DJ1, 2), however at certain node along the column the node displacement (in Z direction in my case) for the same LC exceeds the allowable limit, then what is the use or purpose of the node displacements?

What I understood from many Bentley communities discussion that DFF is applicable for beam (deflection) and column (displacement).

[rupeshkhandekar]

thank you so much for such a great information

[sandipmitra]

Hello Mr. Surojit_ For shear connection in the beams cant we just provide My and Mz and releases and be done to get rid of the instability instead of the partial release?
Another question is that if we give a partial release of the moments in either directions then how are we going to make sure that the provided relaxations in the moment are taken care in the connection design?
Kindly find the time to revert on this

[JSRSUMIT]

Sir, i am designing a steel truss 22m self supporting, mounted with both end with bolt M10x40. can you help me to design. i have made model. but i m facing error while post analysis

[structurelearninghub]

Sir please make a video a double basement building challenges

[rupeshkhandekar]

MAY I GET YOUR CONTACT DETAIL IM MODELINGINGN A PARKING SHED IN THAT IM FACING INSTABILY IN MODEL STILL CAN YOU HELP ME ITS JUST A SIMPLE CANTILEVER PARKING SHED