Specialty Services

Froelich Engineers offers a number of specialty services under the structural engineering umbrella. The following is a sampling of our specialty engineering portfolio in different industries:

  • Dams, Powerhouses, and Spillways
  • Industrial Structures and Facilities
  • Infrastructures and Bridges
  • Underground Structures and Pipelines
  • Post-tensioned Concrete
  • Finite Element Methods
  • Nonlinear/Advanced Analysis and Design
  • Dynamic Analysis
  • Soil-Structure Interaction (SSI)
  • Fluid-Structure Interaction (FSI)

Arrowrock Dam Powerhouse, Idaho

Arrowrock Dam Powerhouse, Idaho

Dams, Powerhouses, and Spillways

Froelich Engineers has been providing structural engineering and construction administration services for various hydro projects, including dams, powerhouses, and spillways. A representative list of projects includes:

  • Arrowrock Dam Power Generation Facility (Near Boise, Idaho), the structural design of the cylindrical concrete structure, with a diameter of 68’ and a submerged depth of 70’, anchored to the bedrock
  • Yellowtail Afterbay Dam Powerhouse (Fort Smith, Montana), design of the new 47’ x 52’ x 85’ tall powerhouse (submerged up to 50’) and 35’ tall retaining wall supported with tiebacks and deadman anchors
  • Pueblo Dam Hydroelectric (Pueblo, Colorado), supporting a pre-manufactured metal building, the 70’ tall powerhouse was designed for submerged water levels of up to 30’ high
  • Tiber Dam Hydroelectric (Liberty County, Montana), FCE provided structural engineering peer review on the project, including hydro-dynamic load analysis, concrete design and rock anchorage
  • Columbia Boulevard Wet Weather Treatment (Portland, Oregon), this massive underground pump station consists of three underground facilities up to 50 feet below grade, and a single above ground control building
  • Pilot Butte Reservoir (Bend, Oregon), The 5-million gallon reservoir was designed and constructed using post-tensioned concrete roof, walls, and mat foundation to support roof soil loads and minimize cracking
  • Central Oregon Pump Stations (Oregon), structural design of several underground sewage pump stations, designed to resist highway traffic loads and floatation from groundwater
  • Sewer Lift Stations (OTAK), structural design of several underground concrete sewage pump stations, designed to resist highway traffic loads and floatation from groundwater
  • Stormwater Storage Tank (Maul Foster & Alongi), structural design of a 20,000-gallon, above-ground, steel-riveted stormwater storage treatment tank using mini-piles due to poor soil conditions

Finite Element Analysis of a Concrete Column and its Connection under Unequal Loads from Corbels

Finite Element Analysis

With years of experience in finite element analysis, Froelich Engineers has been able to provide cost-effective solutions for complex problems for owners and clients in different industries. Applicable to cases were traditional engineering approaches cannot provide the best solutions, finite element analysis is used to push the boundaries of day-to-day engineering designs and provide innovative solutions for complex problems. Combined with other techniques such as nonlinear analysis and principal of fracture mechanics, finite element methods is a powerful method for studying the behavior of different structural systems and components under various loads and conditions. Froelich Engineers have successfully used this technique in a wide range of applications such as buildings, connections, piles, embedded structures, pipelines, shafts, dams, high-rises, marine structures, and more.

Dynamic Analysis of a Mid-rise Building using Acceleration-time History

Dynamic Analysis (Time-history, Response Spectrum, and Vibration)

For certain buildings and structures, such as high-rises, towers, dams, bridges, and structures supporting heavy equipment and vibrating machines, most building codes require a dynamic analysis to be performed. This approach helps the engineer to better understand the response of the structure to changing loads and vibrations and provides more robust solutions in different applications. Froelich’s engineers have used dynamic analysis extensively to perform time-history, response-spectrum, and vibration analysis.

The Erickson Fritz Apartments (Portland, Oregon)

The Crystal Hotel (Portland, Oregon)

Seismic Evaluation and Retrofit

Froelich Engineers has successfully performed the seismic evaluation and retrofit of several projects using ASCE41 regulations. These projects include different types of structural systems and configurations, such as masonry, wood, steel, and concrete structures. In addition to the simplified code-based methods generally used for Tiers 1, 2 and 3, Froelich Engineers has also implemented nonlinear advanced analysis and design approaches for various projects. Application of such complex methods generally results in significant savings in construction cost and time, or could even eliminate the need for the retrofit.

Froelich Engineers has also adopted Matterport, a building imaging tool that saves time on site visits, improves accuracy of existing conditions measurements, and provides a clear visual tool where design teams can review, share, and collaborate on site issues. For more on how we use Matterport on renovation projects, click here.

To see a selection of our adaptive reuse and seismic renovation projects, visit our portfolio.

3D computer model of Gill Coliseum’s partial structure (Corvallis, Oregon)

Friendsview Retirement Community (Newberg, Oregon)

Nonlinear Analysis and Design

Traditionally, engineers use linear elastic analysis and design approaches for their projects. Although this method is still widely used, it lacks the complete control over the response of the structure under extreme loads such as those generated by earthquakes. As a result, design codes and standards, such as ASCE 41, are shifting to recommend the use of nonlinear analysis and design for certain purposes such as seismic retrofit and upgrade of existing structures. This approach can significantly decrease the construction cost and time for seismic upgrade of existing buildings and structures. However, there does not yet exist any consistent or comprehensive body of knowledge that can be used by practicing engineers for this kind of advanced analysis. Fortunately, our seasoned engineers have been able to respond to this shift in industry standards, providing our clients with cost-effective and time-saving solutions that help them make more accurately informed design decisions. 

Some recent projects include: Gill Coliseum (Corvallis, Oregon), Structural strengthening and upgrade of the 60-year old building for installation of new scoreboard and lighting, with a total dynamic weight of 60,000 pounds, using post-tensioned cables Friendsview Retirement Community (Newberg, Oregon), performed seismic upgrade and strengthening of the 5 story concrete structure using the ASCE 41.

2222 NW Raleigh Mixed-use Post-tensioned Concrete Slab (Portland, OR)

Post-tensioned Structures

Froelich Engineers provides advanced post-tensioned design solutions for a wide range of projects including post-tensioned concrete slabs, retaining walls, intake towers, and cable-stayed structures. We also provide routine inspection of these structures to ensure their stability and safety over time.

A representative list of projects includes: Linfield Village (Temecula, California), Structural analysis and design of the post-tensioned concrete floors of the three-on-one, wood and concrete building 2222 NW Raleigh Mixed Use (Portland, Oregon), Structural analysis and design of the complex post-tensioned concrete floors of a five-on-three, wood and concrete mixed-use building, including deep transfer beams and column-on-beam connections Gill Coliseum (Corvallis, Oregon), Structural strengthening and upgrade of the 60-year old building for installation of new scoreboard and lighting, with a total dynamic weight of 60,000 pounds, using post-tensioned cables.

Soil-structure Interaction (SSI) of a Building Foundation with Embedded Deep Shafts in Soft Soils

Soil-structure Interaction

Conventional structural design is acceptable for light structures on relatively stiff soil, such as low-rise buildings and simple rigid retaining walls. Soil-structure interaction analysis is a key consideration for heavy structures such as dams, high-rises, and elevated highways resting on relatively soft soils. Froelich Engineers has a strong track record of projects that successfully implemented the SSI concept during analysis and design. This includes various building foundations, dams, powerhouses, embedded structures, tunnels, underground pipelines, and retaining walls.

Fluid-structure Interaction

Traditional methods are still widely used by design professionals to consider the forces water exerts on structures. However, for complex structures such as dams and spillways in seismic regions, the hydrodynamic interaction between water and structure needs to be explicitly included in the analysis and design. Froelich Engineers’ staff have designed various structures with consideration of the fluid-structure interaction effects. To improve the quality of our designs, some of them have even been cross-checked by laboratory/field tests and advanced CFD (Computational Fluid Dynamics) approaches.

Some of our projects that feature Fluid Structure Interaction analysis and design include: Arrowrock Dam Power Generation Facility (Near Boise, Idaho), the structural design of the cylindrical concrete structure, with a diameter of 68’ and a submerged depth of 70’, anchored to the bedrock Yellowtail Afterbay Dam Powerhouse (Fort Smith, Montana), design of the new 47’ x 52’ x 85’ tall powerhouse (submerged up to 50’) and 35’ tall retaining wall supported with tiebacks and deadman anchors Pueblo Dam Hydroelectric (Pueblo, Colorado), supporting a pre-manufactured metal building, the 70’ tall powerhouse was designed for submerged water levels of up to 30’ high Tiber Dam Hydroelectric (Liberty County, Montana), FCE provided structural engineering peer review on the project, including hydro-dynamic load analysis, concrete design and rock anchorage Columbia Boulevard Wet Weather Treatment (Portland, Oregon), this massive underground pump station consists of three underground facilities up to 50 feet below grade, and a single above ground control building Pilot Butte Reservoir (Bend, Oregon), The 5-million gallon reservoir was designed and constructed using post-tensioned concrete roof, walls, and mat foundation to support roof soil loads and minimize cracking Central Oregon Pump Stations (Oregon), structural design of several underground sewage pump stations, designed to resist highway traffic loads and floatation from groundwater Sewer Lift Stations (OTAK), structural design of several underground concrete sewage pump stations, designed to resist highway traffic loads and floatation from groundwater Stormwater Storage Tank (Maul Foster & Alongi, Inc.), structural design of a 20,000-gallon, above-ground, steel-riveted stormwater storage treatment tank using mini-piles due to poor soil conditions.

Value Engineering

The increasing price of materials has encouraged owners and clients to seek alternative engineering solutions that decrease construction cost and time. This has inspired design engineers to implement more innovative approaches in their design that involves a higher level of analysis. Froelich Engineers’ staff have provided value engineering services in a wide range of projects, from single-story houses to multi-million dollar infrastructure projects.

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