Current and Recent Projects

NSF NEESR LCF

Linked Column Frame structural system for resisting earthquakes. In traditional lateral load resisting systems gravity load-carrying members deform to dissipate seismic input energy. Structural damage can therefore result due to deformations which occur even at levels below a design level event. Such inelastic behavior is directly related to structural damage and thus results in increased retrofit costs and time. The LCF utilizes replaceable links rather than gravity load-carrying members as energy dissipaters. By separating the energy dissipater from the frame’s gravity system, links can be tailored to specific seismic events. In addition to tailoring the links they can be designed to be replaceable, thus allowing for rapid retrofit after a seismic event. Testing in the iSTAR Lab is measuring the effectiveness of the replaceable links for use in the LCF. Links built from W-sections and innovative links built using neoprene core webs are currently undergoing testing. Research into the LCF is being conducted in conjunction with the University of Washington and California State Los Angeles with support courtesy of the National Science Foundation (NSF) and the Network for Earthquake Engineering Simulation (NEES).

Seismic Hazard Analysis of Network of Bridges

Analysis and prioritization of Oregon bridges for seismic hazard. Geologists have indicated that the question is not if a catastrophic earthquake will occur in Oregon, but when one will occur. The risk associated with earthquake hazards on highway systems is largely dependent on the complexity and redundancy of a network in providing smooth traffic flow where bridges present a weak link. Hundreds of bridges in the State of Oregon are vulnerable to earthquake damage. Seismic Risk Assessment studies can provide decision makers with an appreciation of the importance of having a highway network resistant to earthquakes and information to make the network invulnerable to these events. The main objective of this research project is to develop a seismic network model of Oregon highway bridges that appropriately represents the traffic conditions and the seismicity of the Pacific Northwest. The model will be used to analyze the network resulting in recommendations toward bridge retrofit strategies. Project funding was provided Oregon Department of Transportation (ODOT) and Oregon Transportation Research and Education Consortium (OTREC).

Multnomah County FRP Test

Testing of FRP.

The Morrison Bridge steel-grading deck on the draw span is being retrofitted by Multnomah County via pultruded fiber reinforced composite (FRP) decking. The FRP alternative to steel grating is being considered for roadway safety, environmental protection and weight to strength characteristics. An experimental evaluation of the bridge deck is proposed, with objectives of evaluating the structural performance of the different FRP geometric options using equipment and test setup at the iSTAR Lab. Testing will assess the shear and flexural strength of the FRP and connections and fatigue limits through long term high frequency loading. Tests are being conducted in conjunction with Multnomah County with funding support from the Oregon Department of Transportation (ODOT)

Equipment Isolation using Friction Dampers

Study on effectiveness of isolating high voltage equipment using friction dampers.

After an earthquake, electrical sub stations must be operational in order to provide power to essential facilities such as hospitals, fire departments and police stations. Bonneville Power Association (BPA) recognized the need to address the power issue so they called upon the expertise of DQP along with Portland State University’s iStar Lab to develop a base isolation system that will ensure electricity after a seismic event.
A base isolation system separates structural elements from strong ground motion. There are many base isolation systems available; however this particular system the iStar is working on has a series of friction dampers attached at the base of an equipment tower. These friction dampers can be installed with the power on and can be set so lesser forces, like wind, will not affect the equipment tower.Testing in the iStar lab includes static and dynamic loading of various ring spring configuration, numeric modeling and full scale single axis earthquake simulation. iStar has the ability to replicate virtually all earthquake ground motion using a closed loop system. This particular test uses IEEE693 at various levels while measuring 26 different metrics simultaneously at a rate of 200 data points per second.

ICF System Analysis

Small scale tests on various detailing schedules for insulcated concrete forms (ICFs).

Effects of Fillers on Spliced Girder Connections

Testing and analysis of the effects filler plates have on steel plate girder spliced connection strength and deformation. In long span bridge designs cost savings can be obtained through using smaller girders at areas of lower moment. To connect two girders with varied cross section a bolted splice may be used to connect the beams. Filler plates are then used to accommodate the different thickness flanges. Fillers create common faying surfaces and shear planes on each side of the joint and help to reduce any joint eccentricities. There are two types of fillers: developed and undeveloped. Developed fillers are connected by welds or added bolts such that the stresses developed in the connection are distributed over the combined cross section of the filler and the splice plate. Undeveloped fillers are not connected with addition bolts, serve only to provide a common faying surface and move independently as stresses build. Testing of undeveloped splice connections in the lab measured the effect of high performance materials, thick filler plates, and multiple filler plates on spliced connections. Project funding was provided thanks to the Research Counsel on Structural Connections (RCSC) with additional support from Oregon Steel Mills, Fought and Co., and Portland Bolt.

FRP Retrofit of Steel Brace

Retrofit of Bridge Braces for Buckling Restraint Behavior.

The purpose of this study was to develop and demonstrate the concept of retrofitting bridge brace elements with fiber reinforced composites in order to provide restraint against buckling. The advanced materials consisted of a combination of fiber reinforced polymer (FRP) composite pultruded sections and wet lay-up wraps, intended to be applied in the field. A selected number of prototype retrofit bracing specimens were constructed and tested using reverse cyclic loading, and the performance of these specimens was characterized by their compressive strength and their overall hysteretic behavior.

Gusset Plate Analysis

Detailed computer modeling of gusset plate connections in steel truss bridges.
Gusset plates are used to connect chord and web members together at nodes on steel truss bridges. There are currently hunderds of steel truss bridges in service across United States, each containing multipule gusset plate connections. The 2007 collapse of the I-35W Bridge in Minneapolis, Minnesota raised concerns regarding the the potential safety of steel truss bridges, which historically have a reputation for being both economical and reliable. Findings implicated the cause of failure origionated at an under-designed gusset plate, and recommended future inspections to include evalutations of connections; a deviation from the common practice where only truss members are evalutate.
This study’s objective is to develop a computer model of a typical bridge gusset plate connection that can accuratly capture stresses and all applicable failure modes. The computer model will be calibrated with full-scale tests conducted at Oregon State, which will then be used as a basis for further parametric studies investigating gusset plate performance for various out-of-plane buckling conditions, corrosion effects, connection geometry and complex loading conditions. These efforts aim to deepen our understanding of in-situ gusset plate behavior, as well as help develop future assessment tools to help bridge inspectors rapidly identify problem connections. This is a collabrative project between Portland State and Oregon State with funding support from the Oregon Transportation Research Education Consortium (OTREC).

Sponsors and Partners

Oregon BEST

National Science Fundation

American Institute of Steel Construction

Network for Earthquake Engineering Simulation

American Society of Civil Engineers

Boneville Power Association Oregon Department of Transportation

Multnomah County

Gunderson

Underwriters Laboratories

Masonry and Ceramic Institute of Oregon