Three rigid floor diaphragms collect horizontal forces and transfer them through a shear-building model. Compare uniform and height-weighted loading, weaken the first story, and inspect story shear, drift, roof displacement and base overturning.
• A real-time 3D three-story lateral frame (3 m story height) with rigid diaphragms and collectors, floor-force arrows, story drift and displacement indicators, and a foundation base restraint, with home view, focus-selected-part, auto-rotate, expand, show/hide instrument covers and hide-labels controls. • Adjustable peak total horizontal load (100-2000 kN), typical story stiffness (20-100 MN/m), first-story stiffness factor (0.2-1.0) and equivalent floor-force pattern (uniform or height-weighted), with an option for a slow load cycle. • Live measurements of base shear, base overturning moment, roof translation and the first-, second- and third-story drifts. • A Curves & measurements tab with a model response curve, parameter comparison, the model equations and snapshot measurements. • An Experiments tab with presets (uniform versus triangular, soft first story, increased lateral stiffness), pause and time-step controls, a model-verification bench, a timestamped event log and a copyable trial report. • A Learn & assess tab with lessons, a knowledge-check quiz with reset, and a written model-scope statement with a technical reference link.
Floor heights are 3, 6 and 9 m with force weights [1,1,1] for uniform or [1,2,3] for height-weighted loading, so Fi = V × wi/Σwi. Story shear Vi is the sum of the floor forces at and above story i, story drift is Δi = Vi/ki with story stiffnesses [factor × k, k, k], floor translation ui is the sum of drifts up to that story, and base overturning moment is ΣFi hi. The slow cycle factor is (1 − cos(2πt/12))/2.
This is a quasi-static three-story shear-building model with rigid floors and prescribed equivalent forces. The slow animation illustrates load-path changes and is not a dynamic wind or earthquake simulation. It excludes inertia, resonance, torsion, P-Δ effects, member sizing and code seismic coefficients, and deflected geometry is exaggerated while actual millimeter values are displayed.
No. Drift is the difference between adjacent floor translations; roof translation is the sum of the story drifts.
No. This model solves equivalent static equilibrium, without mass or dynamic amplification.
At the same base shear, height-weighted force increases base overturning moment and upper-story demand.
First-story drift grows in inverse proportion to its stiffness factor; at a factor of 0.2 it is five times its original value at the same loading.