ONE GROUND MOTION. TWO INDEPENDENT FRAMES.
Compare. Select. Understand.
A planar teaching model with rigid horizontal diaphragms. Results include gravity. Read assumptions and calibration limits.
Inputs changed. Run the comparison to update results.
Click a column or beam to inspect it
B · High-rise
Below 0.75 0.75–1.0 ≥ 1.0Nominal demand / capacity; no safety classification
Same metres-to-pixels scale and magnification for both frames.
Roof displacement mm · relative
Roof acceleration g · absolute
Peak response & model events
| Frame | T₁ · s | f₁ · Hz | Roof · mm | Drift · % | Base shear · kN | End roof · mm | End time / status |
|---|
End displacement is the displacement at the displayed end time. It is a residual-drift estimate only after free vibration has sufficiently decayed.
MEMBER DETAILS
A · C1-1
Stress recovery uses the current N and M, separately from the frame's effective EI. It does not reconstruct unloading or residual fibre strains from the lumped plastic hinges.
Column · member results
Diagrams use fixed scales from this member's calculated history. Local x runs i → j; A–A follows the selected cut. The cage is a projection of two face rows; anchorage and joints are not detailed.
Section A–A
Normal stress: compression +, tension −. Two bending-face bar rows. The colour scales stay fixed during playback.
Stress distribution through section A–A at the current time
Concrete σx MPa
Reinforcing steel σs MPa
Nominal shear τxy MPa
Depth y starts at the top face. τxy = 1.5 V/(b h) · [1 − (2y/h − 1)²] is a gross rectangular-section estimate; it does not describe diagonal cracking or stirrup stresses.
Stress histories at section A–A
Concrete at top / bottom faces MPa
Steel in top / bottom rows MPa
Edit section, reinforcement & stiffness
Nominal material strengths: no design partial factors. V capacity is a separate user input; stirrup geometry is displayed and does not automatically validate V capacity. Hinge and degradation defaults are illustrative, not experimentally calibrated.
N–M interaction nominal strain envelope
End i moment–rotation kN·m / mrad
End moments kN·m
Shear and axial force kN
A ground motion contains a range of frequencies
Natural frequencies belong to the frame. The Fourier spectrum describes the input; the response spectrum describes the peak response of oscillators. Use both to investigate amplification.
Elastic pseudo-acceleration response spectrum Sa · g
Initial modes & participating mass
| Frame | Mode | T · s | f · Hz | Mass · % |
|---|
Initial eigenmodes include selected gravity P–Δ. All horizontal floor modes are retained. In a nonlinear run, damage can change the effective frequencies; these initial markers are not instantaneous damaged-state frequencies.
Applied ground acceleration g
Five recorded inputs. The same two frames.
Each record is applied to both frames using the selected amplitude rule. Original × factor preserves different PGAs; target PGA makes their PGAs equal. This example collection is not a site-specific design suite.
Run the suite to compare the spread in demand.
| Record | Applied PGA | A roof · mm | B roof · mm | A drift · % | B drift · % | Analysis status |
|---|
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