park_at_crossroads_01

Project Description

Client: The Park at Crossroads
Location: Industry, CA
Surface Area: 180,000 sq. ft.

The Challenges

HSA and Associates was the engineer responsible for the structural design of “The Park at Crossroads” which includes 180,000 square feet of space for lease in a 4-story Class “A” office building. It stands out as one of the tallest tilt-up buildings in “shaky” California at a 60 ft roof height.

The building includes Tilt-up concrete moment frames at building perimeter and Tilt-up Concrete shear wall at the interior with light weight composite floors and roof. A Smart design was employed which included Modal Response Spectrum Analysis to reduce the base shear to realize cost savings and better understand the seismic performance of the building. The original design of 29 Bays of Steel moment Frames with 10 Tilt up shear walls was replaced by just 9 Tilt up shear walls.

Unlike typical tilt-up buildings, panels were connected only where they need to be in the interest of saving excessive number of embed plates at corner conditions from original design. Panels also employ cast-in-place details to connect to foundation. The use of “Hockey Puck” bar terminators for vertical reinforcement at panel to foundation connection enabled new design to exclude all traditional hold-down embeds. Innovative design utilizing reduced connections along with reversed framing at end bays and use of “Hockey Puck” bar terminators provided effective cost and time savings to the project.

All perimeter building panels were designed as special precast concrete moment frame per code without changing original architectural appearance. Precast moment frame on the same line connected adjacent panels with specially designed highly ductile embed plates. Each plate has a reduced section at center and it will transfer loads between panels with all other connections and welds at moment frame designed for the full capacity of plate. The reduced section will yield first during a seismic event acting like a “fuse” between frames in order to provide ductile connections.