ليش فاصل التمدد الزلزالي عندك سقط في فحص المختبر الخارجي — ووش اللي غيّرناه.

The product was rated correctly. The installation was not. A seismic joint is a system — cover plate, anchors, substrate, and the movement it is allowed to absorb — and the lab tests the system, not the brochure.

Our failure traced to anchorage: the fixing centres were specified for a static load, not the cyclic movement a seismic joint sees. The plate held; the substrate around the anchors did not.

We revised the anchor schedule, re-tested, and passed. The lesson is durable — movement capacity is decided at the fixing, long before the cover plate goes on.