1. About & Disclaimer

    This tool allows designers to make an immediate assessment of the dynamic response of a floor solution. The results from this tool provide an improved prediction of the dynamic response compared to the ‘simple method’ in SCI P354. The tool may be used to examine complete floor plans or part floor plans, comparing alternative beam arrangements.

    The tool reports the results of several thousand arrangements of floor grid, loading and bay size, which have been investigated using finite element analysis. The designer must select between a variable action of 2.5 kN/m2 and 5 kN/m2, being typical imposed loads on floors. 0.8 kN/m2 is added to allow for partitions. The designer must also select the arrangement of secondary and primary beams, with typical spans, which depend on the arrangement of the beams. Secondary beams may be placed at mid-span or third points. The pre-set damping ratio of 3% is recommended for furnished floors in normal use.

    When a decking profile is selected, an appropriate range of slab depths are then available to be selected. Generally, thicker slabs will produce a lower response factor. When selecting the slab depth, solutions which result in a response factor higher than 8 (the limit for a typical office) are highlighted.

    The primary and secondary beams are selected automatically as the lightest sections which satisfy strength and deflection requirements; these cannot be changed by the user. A “+” symbol after the member designation means that the section is in addition to those in BS4. The selection of the lightest sections is made to produce the most conservative dynamic response, as stiffer beams will reduce the response. Composite beams may be verified using the composite beam checking tool.

    A visual plot of the response is also provided for both the steady state and transient response. Hovering over the plot shows the response factor. Generally the higher response will be in an end bay, where there is no continuity. The fundamental frequency of the floor is presented on the output screen.

    If the actual design differs from the pre-set solutions in the tool, users should note the following:
    • Using stiffer beams will reduce the response
    • Using thicker slabs, and stiffer beams, will reduce the response
    • The gauge of the decking has no significant impact on the response factor
    • Voids that break the continuity of beam lines will lead to higher response factors

    Although care has been taken to ensure that the calculated resistances are correct, users should verify the output. The Steel Construction Institute and other parties associated with this software and website assume no responsibilities for errors or misuse of this software, or damage arising from use of this software.

  2. Provide Input
    Select the imposed loading, damping ratio, beam arrangement and bay arrangement.
  3. Calculate and review Output
    Report the steady state and transient response factors for the selected arrangement.