Project Profile
Structural Engineering Evaluation and Analysis of Foothill Transit Headquarters
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ABS Group assessed a California building's ability to resist damage during a large earthquake and recommended seismic retrofit options. Read about our award-winning Advanced Engineering project.
Project Objectives
#1
Provide an overview of the structure's seismic lateral force-resisting system and vulnerabilities in the event of an earthquake
#2
Evaluate the seismic integrity of the structural elements against ASCE/SEI Standard 41-06
#3
Recommend seismic retrofit options and estimate costs to repair the building
Project Overview
Foothill Transit needed to improve its understanding of the ability of their existing West Covina, California Administration Headquarters Building to resist earthquake forces. The company wanted to know how the vintage six-story building, which was built in 1969, could be retrofitted to limit structural damage during future large earthquake events.
Foothill Transit also wanted to know the rough estimate of construction costs for various seismic retrofit options to compare (1) the cost benefit of various seismic retrofit options with the reduction in earthquake risk to the building and (2) the potential repair costs in the event of a major earthquake.
Client Needs
Understand the potential impact of a seismic event on the company's headquarters
Determine the cost of seismic retrofit options compared with risk and potential repair costs
Our Solution
ABS Group's Advanced Engineering team developed three-dimensional computer models of the building utilizing the commercially available ETABS modeling and analysis software. We also performed structural engineering calculations to identify specific areas of seismic deficiency relative to code criteria. The engineers assessed strengths, weaknesses, and deficiencies in the building's lateral-force (earthquake)-resisting system with particular attention to critical and major structural members and connections.
Recommend Strengthening Retrofit Options
We developed seismic strengthening concepts to mitigate structural deficiencies and estimated construction costs for budgeting purposes. Our hazard evaluation revealed that the existing exterior cladding system at the north and south elevations of the building was inadequately attached and in need of replacement. We recommended replacing the existing cladding system with a new system.
During the assessment of the building, the following potential strengthening concepts were evaluated:
Provide concrete overlays (i.e. thickened walls) on all existing concrete shear walls at all floor levels
Addition of special reinforced concrete shear walls at the perimeter of the building
Addition of a new special reinforced concrete shear wall adjacent to the non-ductile concrete moment frame at the northeast corner of the building
Utilize an exterior exo-skeleton steel frame system at the outside of the building to provide additional lateral support for the building
Base isolate the building above or below the ground floor level
Provide wall dampers at the existing concrete shear walls
Replace the existing cladding system (travertine) at the north and south sides of the building with a new metal louver system.
Develop Structural Engineering and Architectural Designs
As the Prime Consultant, ABS Group hired a local architectural firm to assist with architectural issues, such as replacement of the existing travertine cladding system with a new vertical metal louver system and installation of a new exterior LED lighting system. ABS Group was responsible for developing structural engineering and architectural design and construction drawings for the new louver system and lighting, as well as providing recommendations for tenant improvements to the existing main lobby and elevators.
Guide Selection of Strengthening Concepts
Each proposed strengthening concept for the building was developed considering the overall constructability in relationship to building operation, with an attempt to minimize potential conflicts with existing building tenants.
In addition, three architectural options were proposed to replace the existing exterior cladding (travertine) system at the north and south sides of the building. Since the existing connections and travertine elements were susceptible to failure during a moderate to large seismic event, a new vertical metal louver system was selected as the final cladding system to replace the existing cladding.
Value Delivered
By implementing the new vertical metal louver system at the north and south sides of the building, Foothill Transit's Administration Headquarters Building's cladding system will be able to resist much higher levels of ground shaking during future earthquake events. In addition, the system is expected to contribute to a more reliable facility that enhances the "life safety" of the building's occupants, as well as minimize business interruption time and substantially lower repair costs following a major future earthquake event.
Awards and Recognition from State Authorities
This project received several awards, including the following:
Business Beautification Award – California Legislature Assembly
2014 West Covina Business Beautification Award – County of Los Angeles
Certificate of Congressional Recognition for West Covina Beautiful – Business Beautification Award
2014 Business Beautification Award – West Covina City Council
From The Knowledge Center
Natural Hazards Risk Management: Post Disaster Recovery from Earthquakes
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