While at Parsons, Chalhoub chaired the committee on base isolation at the Structural Engineers Association of California (SEAOC) and developed the simplified design code on seismic design using shock absorbers which was introduced for the first time in the Uniform Building Code in 1990. Simplified code formulas help engineers worldwide adopt and apply engineering concepts in their daily practice, providing effective design, yet without having to burden themselves with complex research derivations. As a member of the Federal Emergency Management Agency, and as a registered Civil Engineer (P.E.) and Structural Engineer (S.E.) in the State of California, he worked as a chief engineer in disaster relief missions in the Loma Prieta earthquake, the Landers earthquake, and the Northridge earthquake, three major natural disasters that claimed lives and billions of dollars in property and public facility damage.