ECUADOR — October 24, 2026 — MATRIX_CALC, an independent structural engineering review practice that works in English and Spanish, today introduced an independent verification process for structural models built in ETABS and SAP2000. The process rebuilds each model in OpenSees, the open-source structural analysis framework developed at the University of California, Berkeley, and compares the results of both programs element by element. The procedure is documented and reproducible under DOI 10.5281/zenodo.20042213.
Structural analysis software allows complex buildings to be modeled in hours, but a single incorrect assumption, such as a misassigned load case, an unintended rigid diaphragm or a member release in the wrong place, can pass unnoticed from the model to the construction drawings. Independent checking is a long-standing quality-control practice in structural engineering, and an analysis performed in a second, independent program is one of the most direct ways to detect such errors.
In the MATRIX_CALC process, the model is rebuilt from the text file exported by ETABS or SAP2000. Displacements, internal forces and support reactions are compared, and the differences are reported in discrepancy tables that show where the two analyses agree and where the engineer of record should look more closely.
The reviews also cover drawings and calculation reports, with loads, load combinations, analysis and detailing checked against ACI 318, ASCE 7, Eurocode or the Ecuadorian standard NEC-15; seismic analysis, including base shear, lateral force distribution, story drifts, torsion and irregularity checks; and the verification of retaining walls and bridges under Eurocode 7, Eurocode 2, ACI 318 and AASHTO LRFD.
The scope of each review is agreed in writing before work begins, and results are delivered as a report with findings and technical observations, together with editable files: OpenSees scripts, DXF drawings, and Word, Excel and PDF documents. Working in the GMT-5 time zone, MATRIX_CALC operates during the same business hours as offices in the eastern United States and Canada.
Under the MATRIX_CALC approach, the review does not replace the designer: the engineer of record retains authorship, signature and responsibility for the project.
About MATRIX_CALC
MATRIX_CALC is an independent structural engineering review practice based in Ecuador. It verifies structural models, drawings and calculation reports for engineering firms, with written communication in English and Spanish. Further information is available on Telegram at @MATRIX_CAL.
