Barrows Hall, University of California, Berkeley

Owner: University of California Berkeley, Berkeley, CA
Berkeley, CA

Architect: Murakami/Nelson, Oakland, CA
Engineer: Degenkolb Engineers, Oakland, CA
General Contractor: Rudolph & Sletten, Foster City, CA
Total Project Cost: $20 million
Total Project Size: 200,000 sq ft

The University of California, Berkeley contributes $1.23 billion annually to the Bay Area economy, and the Barrows Hall project is one element in the University’s plan to preserve its rank as one of the country’s top research universities and safeguard the community from economic and structural devastation. The comprehensive disaster resistance strategy strives to limit operational interruption, loss of intellectual capital, and the negative impact on the community at-large.

Barrows Hall is an existing eight-story reinforced concrete building constructed in 1964 in accordance with the 1958 Uniform Building Code. Using Federal Emergency Management Agency (FEMA) grants to mitigate post-disaster recovery costs, a solution using exterior reinforced concrete shear walls was developed to strengthen 200,000 square feet of space for approximately $20 million. The added exterior reinforced concrete walls wrap around each end of the building and are interconnected with exterior concrete collector beams on every floor. The focus of seismic strengthening on the building exterior allowed the building to remain occupied during construction, met the University’s enhanced performance objective, and improved the appearance and security of the building.

Structural Framing System

The seismic strengthening work consists of adding full height (eight stories) cast-in-place (CIP) concrete shear walls that wrap around each end of the building in a “C-shaped” pattern. The walls are heavily reinforced and are approximately 24 to 36 inches thick to allow the reinforcing bars to pass by the outer face of the exterior pilasters. The walls are interconnected with added CIP concrete collector beams on the north and south wall of the building at each floor level. The foundation consists of thickened basement walls and spread footings integrated with the existing walls and footings.

Unique Design Features

This project is at the axis of the engineering industry’s shift in convention and move toward performance-based design and engineering standards. Instead of designing strictly to code requirements, FEMA 356 draft standards were used to offer the University several different retrofit schemes that considered the University’s desired level of safety, property protection, and cost of repair in the event of an earthquake at various magnitudes on the Hayward Fault, located within 900 yards of Barrows Hall.

A three dimensional nonlinear static pushover analyses considered actual strength, deformation, ductility, and damage characteristics of building materials under severe seismic demands. The selected scheme consisting of added exterior walls and collector beams was efficient because it allowed the building to remain occupied during construction, and it proved to be adaptable to actual as-built conditions.

Performance based design principles allowed consideration for the strength benefits from the existing building and the ability for the added walls to meet minimum requirements for adequate ductility through either foundation rocking or flexural yielding in the walls and spandrels. The “C-Shaped” wall configuration around each end of the building allowed the walls to pick up necessary dead load for overturning resistance. The added collector beams at each level served two goals; to strengthen the diaphragm to span between the end walls and to force the new walls to work together.

Due to the proximity of Barrows Hall to the Hayward Fault (900 yards), high seismic demands resulted in heavy reinforcing and ductile detailing in the walls, piers and spandrels. To reduce congestion and improve constructibility the following detailing strategies were used:

  • Couplers were used at all large bar splice locations to avoid added steel required for lap splices.
  • Couplers were selected to force yielding in the reinforcement and to achieve high strain levels.
  • T-heads were used at the ends of large bars to eliminate large development length requirements.
  • Confinement reinforcement (ties) were specially designed with consideration for construction sequencing.
  • Additional couplers were added during construction to allow for tolerances in the placement of reinforcement to miss the existing reinforcement.

Strengthening the existing building is a good example of re-use and enhancement of a valuable public asset. As an alternative, demolition and rebuild would have doubled the cost of the project, required extensive hazardous material abatement, and put additional stress on area landfills.

The University now benefits from added security in the event of a natural disaster, because of the building’s enhanced performance and close proximity to the campus police station, the basement now serves as an Emergency Operations Center for the University in the event of an earthquake or other major disaster.