S3DA Design provided structural engineering services for one story residential building in St. Helena, California. The house is 2695 sq. ft. and has 3 Bedrooms, 3 Bathrooms, Dining room, Living room, and family room.

A client approached to us asking to replace the old roof and framing with a new truss roof system. Our Structural Engineering team proposed Scissors trusses to sit on the walls at different levels. In order to improve the stability of the existing CMU walls, our Engineering team designed a concrete tie beam on top of the wall (depth 6”) with No. 4 reinforcing bars under the trusses.

The building was modeled and derivatives were produced in Revit. The calculations for the trusses were ran in ROBOT structure software. Two other phases of construction, tie beams construction and truss framing (accepted as the solution according to California Residential Codes figure R608.9 (4)) were all accomplished in Revit software.

Simpson Strong-Tie LTA2 lateral truss anchors was considered for connection between the trusses and the tie beam.As part of the analysis, we had to show the design capacity of the truss members then compare against demand loads i.e. roof live load, dead loads etc.

Due to the new concrete tie beam installed on top of the existing masonry walls, we had to make sure that the beam is designed to transfer the seismic load to the walls and foundation. Also the adhesive anchors/bars had to be designed to provide this load transfer between the new beam and walls. The task was solved and accomplished and has been submitted for city approval.

It was the first structural engineering project in St Helena, CA That S3DA Design’s structural engineers provided to the private client.