Retrofits
Overview
Commercial buildings are strengthened when a change of use or a large alteration triggers seismic upgrades under the California Existing Building Code (CEBC), when a local retrofit ordinance requires it, when new loads are added, or when an owner wants a known weakness corrected. We evaluate the existing structure, usually following ASCE 41 where a performance-based evaluation is appropriate, locate the critical deficiencies, and design practical upgrades with stamped drawings and calculations for permit.
Typical Projects
- Wall-to-Roof and Wall-to-Floor Anchorage in Tilt-Up and Masonry Buildings
- Diaphragm Strengthening and Added Collectors
- New Braced Frames, Shear Walls and Moment Frames
- Foundation and Column Strengthening for Added Loads
Common Structural Needs
Load Path
A complete path from roof and floor diaphragms through collectors and lateral elements to the foundation, and where it is interrupted.
Wall Anchorage
Out-of-plane anchorage of masonry and concrete walls to roofs and floors, a known failure point in older tilt-up and masonry buildings.
Diaphragm Capacity
Strength and stiffness of wood, metal deck and concrete diaphragms, including openings and chord and collector forces.
Existing Materials
Concrete, masonry, steel and timber strengths established from drawings, field review and testing where needed.
Irregularities
Weak or soft stories, torsion, and abrupt changes in stiffness or strength, as defined in ASCE 7.
Code Triggers
Which CEBC alteration level or local ordinance applies, and the force level it requires of the existing lateral system.
Project Deliverables
- Structural Calculations
- Construction Drawings
- Structural Details
- Specifications and General Notes, as Applicable
- Permit Response / Plan-Check Support
- Construction-Phase Engineering Services, When Included in Scope