Seismodeck: Response Lab

Seismodeck walks a building through a four-step seismic response screening: Site, Structure, Spectrum, Results. The user enters the site class, the mapped short-period and one-second accelerations, the risk category, and the long-period transition. The structure step takes the lateral system, each story's height, effective weight, and lateral stiffness, and a fundamental period from the approximate formula or from the user's own analysis model. The spectrum step draws the design response spectrum with the building period marked and lists the site coefficients and corner periods; values from a site-specific study can replace the mapped ones. The results step reports the seismic response coefficient with the bound that governs it, base shear, the story force distribution, story shears, design story drift against the allowable limit, the P-delta stability coefficient, and a checklist of soft-story, extreme soft-story, weight, and procedural flags. A report tab renders the whole screening as a one-page PDF for sharing. Every screening is saved and listed with search, so an engineer keeps one entry per building and returns to it later. Three worked examples are included: a four-story concrete frame with a soft lobby story, a six-story braced frame with an analysis period above the cap, and a two-story wood library near a mapped fault. Duplicate any screening to try a stiffer story or a different system. Assumptions and limits are stated in the app and printed on the report. The method is the equivalent lateral force form with a 5% damped design spectrum at two-thirds of the MCE, metric period coefficients, story drift from the entered story stiffness, and no torsion, redundancy, or plan irregularity checks. It produces a screening estimate for the engineer's review. It is not a stamped design and does not replace an analysis by the engineer of record. Units are meters and kilonewtons. The app works without a network connection and keeps every entry in its own files.