FT001-b | Pratt Truss

This article describes and explains the influence of bending stiffness of cables on their internal forces. Furthermore, the text provides information on how this influence can be reduced.

To evaluate whether it is also necessary to consider the second-order analysis in a dynamic calculation, the sensitivity coefficient of interstory drift θ is provided in EN 1998‑1, Sections 2.2.2 and 4.4.2.2. It can be calculated and analyzed using RFEM 6 and RSTAB 9.
The coefficient θ is calculated as follows:$$\mathrm\theta\;=\;\frac{\displaystyle{\mathrm P}_\mathrm{tot}\;\cdot\;{\mathrm d}_\mathrm r}{{\mathrm V}_\mathrm{tot}\;\cdot\;\mathrm h}\;$$

For the ultimate limit state design, EN 1998‑1, Sections 2.2.2 and 4.4.2.2 require a calculation considering the second‑order theory (P‑Δ effect). This effect may be neglected only if the interstory drift sensitivity coefficient θ is less than 0.1.

In RFEM 6 and RSTAB 9, you have the option to enter "Visual Objects" as guide objects. You can import the file formats 3ds, stl, and obj.

These objects allow you to create a better reference to the dimensions.

Mia is accessible in the programs and prevents the hassle of following up by email or phone.

Using the "Damper" member type, you can define a damping coefficient, a spring constant, and a mass. This member type extends the possibilities within the Time History Analysis.

With regard to viscoelasticity, the "Damper" member type is similar to the Kelvin-Voigt model, which consists of the damping element and an elastic spring (both connected in parallel).