Structural design of a single-family residence in Chilliwack, BC

Description

The purpose of this project was to complete the structural design of a single-family residence. The structural design of this project included designing the gravity load and lateral system and producing structural drawings. The residence is three stories, with the basement and lower floors partially underground. This is an actual project carried out - with the residence currently in -, excluding the design of shear walls under earthquake loads, details and sections, the design of the two-way slab and concrete beam under the garage, geotechnical considerations for the footings, and the design of connections.

For the gravity load system, I designed the beams, columns, joists, wall studs, concrete bearing walls, and footings. I started by determining which walls were load-bearing by using the truss layout. Next, I calculated the snow load and determined the live load both from NBCC. For the dead loads, I assumed 15 psf for the floor loads and member self-weight. The wind load acting on walls was also determined for the design of the exterior studs. Next, I used load combinations to determine the factored load for each member. I sized the main floor beams using the Wood Design Manual or Weyerhaeuser. Then I designed the columns/jack studs on each end of the beams and the wall studs were designed using timber members.

I checked moment resistance, shear resistance, deflection for the beams, compressive resistance for the columns and interior studs, and combined loads using the interactive equation for exterior studs. After, I transferred all the main floor loads down to the lower floor and then the basement
floor and determined where loads would act and sized the members the same way. In addition, for the lower floor and basement, I designed the joists using Weyerhaeuser TJI 11-7/8 joists. Since the lower floor and basement are underground, I placed reinforced concrete bearing walls
to support the gravity and lateral loads from the soil. Since concrete is heavy, I also calculated the self-weight and determined the wall thickness and required reinforcement. For construction purposes, I designed walls for various locations on the lower and basement floors and used the
designed wall where loading was the greatest for the whole house.

The final gravity component was the footings. For simplicity, only strip footings were used along walls. I determined the area with the greatest loads and used that footing for that section of wall. Using the allowable soil bearing capacity from -, I determined the footing width, thickness, and
required reinforcement. The footings were designed to only support loads from columns, wall studs, and concrete walls. For the lateral system, I only designed the sheathing and nail spacings for the top and bottom plates of each shear wall. To do this, I first determined the wind load on
all surfaces of the residence and chose which walls would be shear walls. Finally, I calculated the force in each shear wall and used the governing wind load for my design.

Finally, I took the architectural drawings and developed structural drawings using all the designed structural components and removing unnecessary information. I either indicated the designed element by directly labelling it on the drawing or using a schedule. I developed the
main, lower, and basement floor drawings as well as the foundation pan. In addition, the footings on the foundation plan are shown to scale relative to the drawing to emphasize areas of greater loading. For my design, I used general reasoning for how far some footings would span.