Question

The story drift of a building provides valuable information about its structural behavior under seismic loads. These could cause large horizontal deformations and even instabilities. Some standards, therefore, call for a check of the story drift in its center of gravity. It indicates, for example, if a second-order analysis (P-Δ effect) is necessary.

RFEM offers the option to perform a response spectrum analysis according to ASCE 7-16. This standard describes the determination of seismic loads for the American market. It might happen that the P-Delta effect has to be considered due to the stiffness of the entire structure in order to calculate the internal forces and carry out the design.

For the ultimate limit state design, EN 1998 1, Sections 2.2.2 and 4.4.2.2 [1], requires the 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. The coefficient θ is defined as follows:
$$\mathrm\theta\;=\;\frac{\displaystyle{\mathrm P}_\mathrm{tot}\;\cdot\;{\mathrm d}_\mathrm r }{{\mathrm V}_\mathrm{tot}\;\cdot\;\mathrm h}\;(1)$$
where
θ is the interstory drift sensitivity coefficient,
P_tot is the total gravity load at and above the story considered in the seismic design situation (see Expression 2),
d_r is the design interstory drift, evaluated as the difference of the average lateral displacements d_S at the top and bottom of the story under consideration; for this, the displacement is determined using the linear design response spectrum with q = 1.0,
V_tot is the total seismic story shear determined using the linear design response spectrum,
h is the interstory height.

In the "Edit Section" dialog box, you can display the buckling shapes of the Finite Strip Method (FSM) as a 3D graphic.

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.

Do you have individual column sections and angled wall geometries, and need punching shear design for them?

No problem. In RFEM 6, you can perform punching shear design not only for rectangular and circular sections, but for any cross-section shape.