Issue with Chord Rotation Capacity Calculation in SeismoStruct Using NTC Standards

[Daniele.arcuri]

Hello everyone,

I am encountering a doubt with the calculation of the rotation capacity in SeismoStruct when using the NTC standards for verification. Specifically, I observe large variations in the rotation capacity at the chord with minimal changes in the shear span (M/V ratio) (other parameters, including the mechanical percentage of tensile and compressive longitudinal reinforcement, remain unchanged).

For example, in my NLTH analysis, at step 1.61s, the shear span is 0.60796414 meters, and the calculated rotation capacity is 0.01057372 (perfect match with my hand calculation). However, at the next step (1.62s), the shear span changes slightly to 0.607226977 meters, and the rotation capacity suddenly increases to 0.02095776. This drastic change seems to occur when a certain limit is surpassed, although all other parameters remain constant.

Could anyone provide insights into why SeismoStruct behaves this way? Are there specific shear span limits defined within the software when using the NTC standards for section verification? Any advice or clarification on this matter would be greatly appreciated.

Thank you for your assistance.

Best regards,

Daniele

[z.gronti]

Dear Daniele.arcuri,

Could you please send me your project with detailed explanation of your calculations to z.gronti@seismosoft.com to check it?

[Daniele.arcuri]

Dear Zoe Gronti,

I’ve actually solved the problem. I hadn’t realized that the software imposes limits on the shear span (Lv) to avoid meaningless values. After reviewing the Detailed Calculation Report, I discovered that the shear span must meet the following criteria: Lv > 0.1L and Lv < 2L. If these conditions aren’t met, the software automatically sets the shear span to L/2. This clarification resolved the issues I was facing.

Thank you very much for your help!