General guide

Chronological Sequence

At a glance: The use of the application to follow a chronological sequence of events is described in this User Guide. Here is a discussion of aspects common to the application on any device. Details of the various procedures on the different kinds of devices are described in the Mac & PC volume, and in the Android phone, iPhone & iPad volume.

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The chronological sequence

A sequence of computations that follows the chronological sequence of events in the life of a structural member is envisaged. It is also envisaged that such a sequence will be repeated many times as a design progresses from an initial concept to a final perfected design.

Load cases with all three loading variable as objectives

Both the adoption of a stage load and also the computation of creep require a load case where all three loading variables are objectives. This is one of the purposes of the “Given bending moment” method. This method will not work however in situations where the bending moment is small. An example to illustrate this is a pretensioned member immediately after the tendons are released. The method “Utility: Curvatures and axial load” is provided for this situation. In the case of the pretensioned member immediately after the tendons are released the axial load is zero. With the curvatures also set to zero this method will compute the bending moment if the member stays flat on the pretensioning bed.

The curvatures can be adjusted manually to find the curvatures caused by the various bending moments the new member might be subjected to.

Time affects

The use of Time Affect Sets is describe under the heading ‘Time Affect Sets’ in this volume of the User Guide and also in the volumes specific to the different kinds of device.

The application of time affect sets is part of the envisaged chronological sequence.

Adopting a stage load

The adoption of stage loads is also part of the envisaged chronological sequence.

The initial state and stage distortion facilities have a purpose illustrated by two parallel structural members in close association but structurally independent; each having a loading and corresponding distortions. At a particular instant in the construction process these two members are joined so they act as one structural member. Immediately after that instant the resulting member has a loading that is the combined affect of the two loadings before and each component has the same distortion as before that instant. Those distortions are referred to as the stage distortions (if adopted as such), and the combined member is said to be in an initial state.

The procedures described in this user guides use three XSF files; one for each of the contributing members cross-sections, and one for the resulting member cross-section. A procedure is set out in the user guide volumes for the specific devices.

Those descriptions of the procedure have been devised to cope with the most complicated design. In practice often the procedure can be less complicated. For example the setting of wet concrete can be perceived as the instant of joining; the newly set concrete and any mild steel embedded in it being one of the contributing members. That contributing member has no loading and no distortion. In these cases the XSF file for the other contributing member can be used for the resulting member. In effect the new concrete is added.