Influence lines are less important nowadays due to fast computer systems. However, it might be an advantage to use influence lines in the phase of preliminary design, as well as in the actual creation of the structural designs. With the RF-INFLUENCE add-on module, influence lines and influence surfaces can be generated and evaluated easily due to a fixed internal force. This technical article describes, with a simple example, the basics of determining and evaluating influence lines.
Requirements for the design of structural stability are given in the AISC 360 – 14th Ed. Chapter C. In particular, the direct analysis method provisions, previously located in Appendix 7 of the AISC 360 – 13th Ed., are described in detail. This method is considered an alternative to the effective length method, which in turn eliminates the need for effective length (K) factors other than 1.0.
This part explains the determination of forces arising when screwing a straight cross-laminated timber plate to a curved glulam beam. For this, a glulam beam with a curved member was modeled in RFEM. The member has a precamber of 12 cm, since the preliminary design showed that the applied precamber of 6 cm will never be sufficient to maintain l/300. The dimensions of the bottom chord are 12 cm wide by 32 cm high. The plate was selected in RF‑LAMINATE as a three‑layer plate with a thickness of 8 cm.