Resources Renewed

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The 17-story Resources Building was a marvel when built. Located just two blocks from the California State Capitol in downtown Sacramento, the building was the fourth largest office space west of Chicago upon completion in 1964. The towering 657,000 sq. ft. workplace got its name from the State of California departments it housed: Forestry and Fire Protection, Parks and Recreation, Natural Resources, and chiefly, Water Resources. In addition to providing office space for 2,000+ employees, the building’s rooftop housed components for the California Public Safety Microwave System—cutting-edge communication technology in the 1960s.

Unfortunately, time was not kind to Sacramento’s once-tallest building. A 2014 study by the California Department of General Services (DGS) identified several seismic deficiencies and the absence of modern high-rise fire and life-safety elements, putting the building’s occupants at “high risk” should an earthquake, fire, or any other emergency event occur. The following year, a statewide property assessment deemed it the State-owned building most in need of repair and identified numerous additional issues: A “spongy” roof susceptible to leaks. Asbestos in the floor, ceiling, and insulation. Electrical breakers with a history of safety problems. Lead paint. Windows that hadn’t been washed in 10 years due to a broken crane. An inadequate fire sprinkler system. In total, the 2015 assessment estimated $149M in repairs were needed within the next 12 months.

Given the litany of issues and high repair cost, questions surrounding whether it would be better to completely demolish the building and construct one anew naturally arose. However, the building was considered historic on the basis of age. Furthermore, the project Environmental Impact Report noted a significant prehistoric archeological resource was previously uncovered in the area adjacent to the Resources Building, and earthwork activities associated with replacing the structure were deemed a greater risk of destroying potentially undiscovered resources. Lastly, the location’s proximity to the State capitol meant that new construction would have to adhere to current zoning height restrictions, which would have greatly reduced a new building’s square footage. All issues considered collectively, the decision to renovate the existing building was solidified.

The Resources Building is 300 feet long by 130 feet wide with an overall height of 232 feet. Typical grid dimensions are smaller than one might expect: 20 feet by 26 feet. Story heights between floors are generally 13 feet, 4 inches. The structural frame consists of 1960s-era steel construction and includes concrete fill over shallow metal deck spanning to wide-flange beams, girders, and columns employing bolted double-angle shear and bearing connections and bolted column splices throughout the building. Steel truss moment frames comprise the lateral force-resisting system with double-angles forming the top and bottom chords and the diagonal web members. The truss moment frames are typically constructed with shop-welded connections between the webs and chords and with field-bolted connections of the last double angle to the gusset plates at the columns.

DGS has significant experience procuring projects using Design-Build contracts for new construction, but less experience with the same procurement method for renovation projects. Despite this lack of experience, DGS leadership realized an existing building renovation of this magnitude needed a delivery method with more flexibility to account for the many unforeseen conditions that would likely occur throughout the life of the project. As a result, the State selected Progressive Design-Build for their delivery method to allow greater design development and extensive site exploration to minimize risk and improve the certainty of the Guaranteed Maximum Price (GMP).

The main objective of the project was to extend the useful life and viability of the building and provide a modern, efficient, and safe environment for State employees and the public they serve. This meant removing and abating hazardous materials, correcting seismic and fire/life-safety deficiencies, and upgrading all infrastructure systems, including MEP, HVAC, telecommunications, and security. All building envelope elements, including the roof, windows, and exterior precast panels, were to be removed and replaced. Additionally, three 17-story exit stair cores were to be reconstructed.

Achieving these goals meant stripping the building down to its structural frame. Due to the historic status of the building, the renovation plan and all other proposed changes were reviewed by the State’s historic preservation officer, who was also charged with ensuring the new design respected the International Style expressed in the original design as well as the equally historic Leland Stanford Mansion located nearby across the alley.

Many means and methods of the original design and construction were known at the start of the project, but still a great many remained unknown. Drawings used to validate the project were incomplete, so the Buehler team scoured the DGS plan room for two days, uncovering additional drawings for the entire team to use.

This effort yielded an interesting wrinkle about the steel frame. The drawings stated that the majority of steel used was of the high-strength ASTM A440 variety as opposed to the more common ASTM A36 type. Some steel coupons of the frames were taken and testing confirmed the presence of A440, which is more common for steel connected using rivets instead of bolts and welds. Though higher strength, A440 steel has different metallurgic properties that required the establishment of special welding procedures. By identifying this issue before a GMP was established, these special welding procedures were easily accommodated into the project scope.

One large unknown remained despite discovering additional drawings: the original foundation and pile system. The original design documents allowed four possibilities, but analysis that incorporated the lower limits of compression and tension of the different types led to vastly different strengthening requirements.

With permission from DGS, the project team decided to perform destructive exploration to gather necessary information. Certain areas at the exterior of the building proved optimal for excavation as the building was unoccupied, and it was determined that there were minimized loading demands upon the selected pile caps. Following the installation of temporary shoring, excavation uncovered the building had step-tapered piles—a type not uncommon for downtown Sacramento given the era of construction.

This investigation into the pile types also yielded something unusual about the construction methods used for the original foundation. Before installing the piles, the area was completely excavated down approximately 10 feet to 12 feet, piles were drilled, pile caps formed, and the remaining hollow space was backfilled with sand.

To help mitigate another significant project risk, DGS gave the project team approval to remove one of the building’s exterior precast panels to help determine demolition expediency and overall project cost. Once again, another interesting tidbit was uncovered: the concrete deck slabs were cast directly against the exterior precast panels without any kind of separation, forming cold joints at every floor. Although the drawings did not indicate any method for creating a break between these two elements, it was expected that some sort of break would be discovered. What was found was quite the opposite—a strong bond between the floor slab and precast panel enhanced by roughened surfaces on the back side of the precast panel. The precast panels were already set to be removed from the building, but this finding meant that the design-build team needed to modify the sequence and time allotted for removing the panels. By removing one of the precast panels during this exploratory phase, the team was able to validate a proposed demolition concept without the need to price this uncertainty into the GMP.

Now armed with additional knowledge, the team proceeded to the evaluation and design phases of the project. Development of an optimal retrofit solution necessitated extensive study of the expected seismic performance of the existing structure in its current condition.

When renovating its office buildings, the State requires compliance with the California Existing Building Code (CEBC). The 2019 CEBC was the governing code for this project and stipulates a seismic evaluation and/or retrofit using ASCE 41 must be conducted to satisfy dual seismic performance objectives of “life safety” performance at the Basic Safety Earthquake (BSE) 1E seismic hazard level, and “collapse prevention” performance at the BSE-2E level. Given the building’s age, height, lateral system, and type of steel used, the team understood that a nonlinear time history analysis—rather than other linear or nonlinear approaches—would be the most appropriate method to evaluate performance and define the seismic retrofit measures necessary for meeting code requirements while simultaneously providing the best value to the project. The nonlinear analysis was completed using ASCE 41-17 as the primary standard for modeling parameters and acceptance criteria and was supplemented with provisions from ASCE 7-16 when appropriate. More specifically, the seismic evaluation followed the ASCE 41-17 Tier 3 Systematic Evaluation and Retrofit procedures relative to the applicable performance objectives of the CEBC.

Close collaboration with the project geotechnical engineer Geocon was warranted to select the appropriate ground motion records for the analysis, which applied 11 records in each primary direction of the structural system. These records were selected and scaled to reflect the seismicity and soil conditions of the project site relative to the BSE-1E and BSE-2E seismic hazard levels specified by the CEBC. The site-specific spectral acceleration parameters for the two seismic hazard levels are S_s = 0.235 and S₁ = 0.106 for BSE-1E, and S_s = 0.427 and S₁ = 0.194 for BSE-2E.

Even with the generally moderate seismicity of Sacramento, initial analysis of the as-built structure indicated significant structural deficiencies throughout the building, with an abundance of components failing to meet the collapse prevention performance criteria associated with the BSE-2E hazard level. The following behaviors were predicted to occur in numerous locations: buckling of the bottom chord of the steel truss moment frame, buckling of web members of the steel truss moment frame near columns, excessive yielding and/or fracture of myriad welded and bolted connections within the steel truss moment frames, and excessive yielding and/or fracture of connections from the trusses to the columns. Foundation uplift capacity also appeared to be lacking.

Further analysis was conducted in consideration of various retrofit strategies, including “brute force” solutions such as strengthening of all deficient conditions, as well as essentially abandoning and replacing the existing steel truss moment frame system by adding new braced frames throughout the building.

As the results of the various studies were further examined, it became clear that the steel truss moment frame members and connections were lacking reserve capacity and were limited by nonductile failure mechanisms associated with story drifts and joint rotations. The frames appeared to lack the ability to redistribute load through ductile mechanisms to other portions of the frame or to other portions of the building, meaning that yielding of one component usually triggered a nonductile failure of that component or an overload of an adjacent component. This behavior was not isolated to a general region, specific floor, or particular line, but was instead prevalent throughout the entire building. The time history analysis indicated that inadequate capacity and unacceptable nonductile mechanisms occurred with seismic story drifts as small as 0.5%.

Conceptual retrofit studies focused on minimizing the need for strengthening the steel frame due to the A440 steel and nonductile connections. These studies quickly identified the use of fluid viscous dampers and their ability to reduce demands on the steel truss moment frames as the approach likely to meet all project goals, including providing the best value to the State.
Taylor Devices, the selected the damper manufacturer, brought a collaborative approach to placement analysis and design. The team performed iterative studies to develop a strategy for the most effective damper placements and sizes. The sensitivity to exceeding such low story drifts generally controlled the development of the damper retrofit configuration. In the end, a total of 128 dampers of differing sizes and damping characteristics were incorporated, which eliminated approximately 90% of the steel frame locations originally identified in the preliminary studies as needing steel frame strengthening, and resulted in about 50% less new helical piles needed to supplement the foundation system. The strengthening of the steel truss moment frames was mostly limited to minor bottom chord bracing at many of the trusses. At locations where dampers were added, only minimal, localized strengthening of a small handful of existing columns was needed, which was done by adding plates to create a boxed section. It is estimated that approximately $2M was saved due to the extensive nonlinear analysis and fine-tuning of the damper configuration.

Marrying both function and form, the project team decided to leave the dampers exposed and display them prominently in the new floor plan designs to signal the building’s enhanced safety. This also helped achieve one of the State’s primary goals of providing their employees confidence that their workplace is in a safe structure of high-quality that emulates a new building.

The renovation was a smashing success thanks to meticulous structural investigation, analysis, and detailing; collaborative cooperation amongst project partners; and thoughtful engagement by ownership from start to finish. The building received its Certificate of Occupancy two months ahead of schedule and the project stayed within budget, maximizing value to the State.

Employees started moving into the updated spaces Nov. 3, 2025, although they are not the same ones who previously paced their passageways—those workers have since moved into the 22-story New Natural Resources Headquarters in the block directly southwest. Instead, the revitalized building now serves as the headquarters of the California Labor and Workforce Development Agency and its 40 user groups, including the Employment Development Department, Department of Industrial Relations, and the Workforce Development Board. The State held a ribbon-cutting Jan. 21 and unveiled a no-nonsense new name for the building fitting of both its tenants and all the hard work that went into unleashing its full potential: Labor Building. ■

About the Authors

Jason Horwedel, SE, DBIA is a Principal at Buehler who specializes in large design-build projects, including sports and entertainment venues, civic facilities, and healthcare structures. (jhorwedel@buehlerengineering.com)

Matt Williams, SE, is an Associate Principal at Buehler whose projects include hospital expansions, government headquarters buildings, and airport facilities.

Phil Petermann is a Technical Writer at Buehler who got started in AEC performing historic concrete preservation at Alcatraz Island as a student at CSU Chico.