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Dynamic analysis & influence lines ​

The response spectrum analysis dialog

Beyond static, P-Delta, buckling and modal, Studio has three focused analysis tools in the File menu (also reachable from the Ctrl/Cmd+K command palette). Each opens a self-contained dialog and runs the WebAssembly solver locally.

Response spectrum ​

File ▸ Response spectrum runs a modal response-spectrum analysis (SRSS or CQC) on the current model. Mass is taken from the model.

  1. Set the direction (X / Y / Z), number of modes, damping ratio, and the combination method (CQC or SRSS).
  2. Edit the design acceleration spectrum as period, accel points (one per line, in m/s²) - replace the default with your code spectrum.
  3. Run analysis.

Results show the combined base shear, total mass, the effective-mass capture (aim for ≥ 90% - add modes if it is low), the peak nodal translation, and a per-mode table (period, spectral acceleration, participation factor Γ, effective mass, base shear). Copy the summary with the ⧉ Copy button.

Time history ​

File ▸ Time history runs a modal time-history analysis (Newmark-β, average acceleration - unconditionally stable) from a ground-acceleration record.

  1. Choose the direction, modes, and damping ratio.
  2. Paste a record as time, accel points (seconds, m/s²) - or click Load sample pulse to try it with a built-in damped sine.
  3. Run analysis.

You get the peak base shear (per axis and governing), the peak nodal translation, and the integration summary (steps · Δt · modes). Paste a real accelerogram for a project run; the sample is just to see the tool work.

Influence lines & moving loads ​

File ▸ Influence lines builds a single-span analytical influence line - the tool bridge, crane and moving-load problems are built on.

  1. Enter the span, support (simply supported, cantilever, fixed-fixed, fixed-pinned), the action (moment, shear, reaction) and the station along the span (or which support, for a reaction).
  2. The influence line is plotted live, with the peak ordinate marked.
  3. Optionally add an axle train: axle weights (kN) and spacings (m). The dialog reports the maximum and minimum effect of the moving load and the critical axle positions.

Worked sanity checks: a simply-supported mid-span moment influence line peaks at L/4; a single point load on that span gives a maximum moment of PL/4.

TIP

These are quick design tools - verify against the governing standard before professional use, the same as every other check in Studio.