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Full-Text Articles in Engineering

Thin-Film Sensor For Fatigue Crack Sensing And Monitoring In Steel Bridges Under Varying Crack Propagation Rates And Random Traffic Loads, Xiangxiong Kong, Jian Li, Caroline Bennett, William Collins, Simon Laflamme, Hongki Jo Jan 2019

Thin-Film Sensor For Fatigue Crack Sensing And Monitoring In Steel Bridges Under Varying Crack Propagation Rates And Random Traffic Loads, Xiangxiong Kong, Jian Li, Caroline Bennett, William Collins, Simon Laflamme, Hongki Jo

Civil, Construction and Environmental Engineering Publications

Fatigue cracks are critical structural concerns for steel highway bridges, and fatigue initiation and propagation activity continues undetected between physical bridge inspections. Monitoring fatigue crack activity between physical inspections can provide far greater reliability in structural performance and can be used to prevent excessive damage and repair costs. In this paper, a thin-film strain sensor, called a soft elastomeric capacitor (SEC) sensor, is evaluated for sensing and monitoring fatigue cracks in steel bridges. The SEC is a flexible and mechanically robust strain sensor, capable of monitoring strain over large structural surfaces. By deploying multiple SECs in the form of dense ...


Epics Gaqt: Nandi Clean Kitchen Study, Yichen Fan Dec 2018

Epics Gaqt: Nandi Clean Kitchen Study, Yichen Fan

Engagement & Service-Learning Summit: Connecting Through Listening & Scholarship

No abstract provided.


On The Development Of 8,000 Psi Geopolymer Mortar For Practical Use In Field Applications, Remington Gabriel Reed Dec 2018

On The Development Of 8,000 Psi Geopolymer Mortar For Practical Use In Field Applications, Remington Gabriel Reed

Theses and Dissertations

Although there are several perceived benefits from the use of geopolymer binder as an alternative to ordinary portland cement in concrete materials, it is not widely used in field applications. Geopolymer materials have no set guidelines for mixture design and often require heat curing to facilitate strength gain. Additionally, many geopolymers are created using carefully controlled and high quality materials and activator chemicals. These factors greatly affect the practicality of the material. The goal of this research was to create a geopolymer material capable of achieving high compressive strengths at 28 days without heat curing, and using only readily available ...


Effect Of Continuity Plate Eccentricity On The Performance Of Welded Beam-To-Column Connections, Jason Thomas Norwood Dec 2018

Effect Of Continuity Plate Eccentricity On The Performance Of Welded Beam-To-Column Connections, Jason Thomas Norwood

Theses and Dissertations

Beam-to-column connections in structural steel buildings may have varying degrees of rotational restraint and varying degrees of moment transfer. In fully restrained moment connections, shear is typically transferred through the beam web, while the moment is mostly transferred through the beam flanges which create tension/compression force couples. Column sections that are incapable of resisting these flange forces are often retrofitted with continuity plates within the connection region to improve capacity. In cases of unequal beam depths on either side of the column, an eccentricity between the framed-in beam flange and continuity plate may be required; however, limited research exists ...


Young’S Modulus As A Measurement To Estimate Damage Related With Alkali-Silica Reaction In Concrete., Anazaria J. Ortega Gonzalez Dec 2018

Young’S Modulus As A Measurement To Estimate Damage Related With Alkali-Silica Reaction In Concrete., Anazaria J. Ortega Gonzalez

Civil Engineering Undergraduate Honors Theses

The main purpose of this research is to compare two nondestructive methods to assess Alkali-Silica reaction (ASR) in concrete. Fifteen concrete prisms were cast using aggregates with different Alkali-Silica reactivity such as Jobe sand and Van Buren sand. The change in strain, shear wave velocity and Young’s modulus were determined according to ASTM C129 and ASTM C215, respectively. This data was collected by Dillon K Self, who determined that the shear wave velocity and strain are inversely proportional. However, when single cracking in the concrete specimen transition to map cracking, the shear wave velocity dropped significantly, whereas the strain ...


The Live Load Response Of The Open Web Steel Joist Black Slough Bridge, Piero Caputo Dec 2018

The Live Load Response Of The Open Web Steel Joist Black Slough Bridge, Piero Caputo

All Graduate Plan B and other Reports

The bridge being studied spans the Black Slough River in the Nucor/Vulcraft facilities near Brigham City, Utah. The bridge is composed of seven heavyweight open web steel joists supporting a concrete deck-slab element and sitting in two concrete cantilever walls serving as bearings. A full-scale live-load test was performed using forklift vehicles at four locations on the deck. During the test, axial strains, deflections, and rotations where measured.

In their provisions, the American Association of State Highway and Transportation Officials (AASHTO) included a simplified number of equations and solutions used to calculate GDFs for standardized decks supported by beam ...


Sensor-Enhanced Analysis And Behavior Of Steel Beams In Fire, Genda Chen Nov 2018

Sensor-Enhanced Analysis And Behavior Of Steel Beams In Fire, Genda Chen

Genda Chen

Traditionally, strain data are difficult, if not impossible, to obtain from steel structures in fire due to their harsh environment and temperature measurements are limited to the locations of thermocouples. This paper presents high-temperature measurements using a Brillouin scattering based (distributed) fiber optic sensor and the application of the measured temperatures and material parameters recommended in building codes into the enhanced thermo-mechanical analysis of simply-supported steel beams subjected to combined thermal and loading effects. The distributed temperature sensor captures detailed, non-uniform temperature distributions that are compared locally with thermocouple measurements by less than 5% at a 95% confidence level. The ...


Investigation Of A Tractor-Tank Trailer Roadside Containment Barrier, Dean L. Whitfield Nov 2018

Investigation Of A Tractor-Tank Trailer Roadside Containment Barrier, Dean L. Whitfield

Civil Engineering Theses, Dissertations, and Student Research

The objective of this research project was to develop a new, cost-effective, Manual for Assessing Safety Hardware (MASH) Test Level 6 (TL-6) barrier. A literature review on prior Test Level 5 and Test Level 6 barriers was conducted, and the cost of current TL-5 and TL-6 barriers was established. Existing and modified design procedures for roadside barrier were reviewed as well as current TL-6 design forces. A preliminary TL-6 truck model was developed in LS-DYNA. The minimum barrier height to contain a tractor-tank vehicle was determined to be 62 in. for a rigid, vertical-faced barrier through LS-DYNA computer simulation. New ...


Cementitious Sensors Exhibiting Stopbands In Acoustic Transmission Spectra, Shreya Vemuganti Nov 2018

Cementitious Sensors Exhibiting Stopbands In Acoustic Transmission Spectra, Shreya Vemuganti

Shared Knowledge Conference

Ultrasonic monitoring in cementitious materials is challenging due to the high degree of attenuation. In wellbore environments, monitoring becomes more challenging due to inaccessibility. Meta materials, also known as acoustic bandgap materials, exhibit an interesting feature of forbidding the propagation of elastic/sound waves and isolate vibration in a certain frequency band. Traditionally, acoustic bandgap materials are developed with inclusions such as tin, aluminum, gold, steel in a polymer matrix. In this study, we present the development of three-dimensional cementitious sensors capable of exhibiting stopbands in the acoustic transmission spectra using carbon nanotubes. Relatively wide stopbands were engineered using Floquet-Bloch ...


Development, Training, Education, And Implementation Of Low-Cost Sensing Technologies For Bridge Structural Health Monitoring (Shm), Fernando Moreu, Chris Lippitt Nov 2018

Development, Training, Education, And Implementation Of Low-Cost Sensing Technologies For Bridge Structural Health Monitoring (Shm), Fernando Moreu, Chris Lippitt

Publications

Transportation infrastructure needs continuous monitoring. However, traditional inspections cost money and are conducted visually. New technologies for bridge monitoring are expensive and complex. This project involved developing cost-effective sensor technologies that can be applied towards the maintenance of railroad bridges by recording reference-free transverse displacement. More specifically, this project developed new applications of new technologies (Arduino, wireless smart sensors, drones, Hololens) and promoted workforce development with an emphasis on outreach of high-school students. This project was carried out in three main phases: (1) development and validation of technologies, (2) education and outreach to students, and (3) outreach to industry consisting ...


Sustainability-Based Long-Term Management Of Bridges Under Multi-Hazard Exposure, Mohamed Soliman Nov 2018

Sustainability-Based Long-Term Management Of Bridges Under Multi-Hazard Exposure, Mohamed Soliman

Publications

Bridges are under deterioration due to various mechanical and environmental stressors. Hydraulic-related hazards (e.g., flood and scour), aggressive environmental conditions, and seismic events (e.g., earthquake) are recognized as the most significant threats to the safety of bridges. In traditional risk assessment methods for structures susceptible to damage due to floods and other natural hazards (e.g., corrosion and seismic events), future hazard predictions are conducted using historic return periods and climate records. However, recent increase in flood intensity in central-southern states indicate that future hazard occurrence rate may not necessarily follow past trends. Accordingly, current design, assessment, and ...


Survival Analysis Of Bridge Superstructures In Wisconsin, Azam Nabizadeh, Habib Tabatabai, Mohammad A. Tabatabai Oct 2018

Survival Analysis Of Bridge Superstructures In Wisconsin, Azam Nabizadeh, Habib Tabatabai, Mohammad A. Tabatabai

Civil and Environmental Engineering Faculty Articles

Although survival analyses have long been used in biomedical research, their application to engineering in general, and bridge engineering in particular, is a more recent phenomenon. In this research, survival (reliability) of bridge superstructures in Wisconsin was investigated using the Hypertabastic accelerated failure time model. The 2012 National Bridge Inventory (NBI) data for the State ofWisconsin were used for the analyses. A recorded NBI superstructure condition rating of 5 was chosen as the end of service life. The type of bridge superstructure, bridge age, maximum span length (MSL) and average daily traffic (ADT) were considered as possible risk factors in ...


Corrosion Resistance Of Pipeline Steel With Damaged Enamel Coating And Cathodic Protection, Liang Fan, Signo Tadeu Dos Reis, Genda Chen, Michael L. Koenigstein Oct 2018

Corrosion Resistance Of Pipeline Steel With Damaged Enamel Coating And Cathodic Protection, Liang Fan, Signo Tadeu Dos Reis, Genda Chen, Michael L. Koenigstein

Genda Chen

This paper presents the first report on the corrosion resistance of pipeline steel with damaged enamel coating and cathodic protection in 3.5 wt % NaCl solution. In particular, dual cells are set up to separate the solution in contact with the damaged and intact enamel coating areas, to produce a local corrosion resistance measurement for the first time. Enamel-coated steel samples, with two levels of cathodic protection, are tested to investigate their impedance by electrochemical impedance spectroscopy (EIS) and their cathodic current demand by a potentiostatic test. Due to its glass transition temperature, the enamel-coated pipeline can be operated on ...


Training Framework Of Robotic Operation And Image Analysis For Decision-Making In Bridge Inspection And Preservation, Ruwen Qin Oct 2018

Training Framework Of Robotic Operation And Image Analysis For Decision-Making In Bridge Inspection And Preservation, Ruwen Qin

Ruwen Qin

Inspection and preservation of existing transportation infrastructure to extend their service life is an effective way of mitigating the pressure of steadily growing transportation demands on the aging infrastructure. Their current practice, though, represents one of the most costly operations in state departments of transportation.

The INSPIRE University Transportation Center will develop a remotely-controlled robotic platform that helps with these labor-intensive tasks and allows engineers to focus on decision-making processes. An important mission of INSPIRE is to leverage users’ capability of implementing, and interacting with, the robotic platform. Therefore, a long-term plan has been made to create a framework of ...


Uav-Enabled Measurement For Spatial Magnetic Field Of Smart Rocks In Bridge Scour Monitoring, Genda Chen Oct 2018

Uav-Enabled Measurement For Spatial Magnetic Field Of Smart Rocks In Bridge Scour Monitoring, Genda Chen

Genda Chen

Foundation scour is the main cause of bridge collapses in the U.S. In 2011, the principal investigator (PI) proposed smart rocks with embedded magnets for bridge scour monitoring. Once deployed around a bridge pier, smart rocks as field agents offer mission-critical information about the maximum depth of a scour hole developed around the bridge foundation – the key parameter that is used to assess foundation stability in engineering design and retrofit. Smart rocks have recently been deployed and tested at three bridge sites in California and Missouri. With multiple measurements, they can be located with an accuracy of 0.5 ...


Hyperspectral Image Analysis For Mechanical And Chemical Properties Of Concrete And Steel Surfaces, Genda Chen Oct 2018

Hyperspectral Image Analysis For Mechanical And Chemical Properties Of Concrete And Steel Surfaces, Genda Chen

Genda Chen

A typical human eye will respond to wavelengths from approximately 400 to 700 nm. A hyperspectral camera can extend the wavelength to as high as 2500 nm. This extension will allow engineers to find objects, identify materials, and detect processes on structural surface, which cannot be done with visual inspection.

This project aims to develop an open-source catalogue of concrete and steel surfaces and their spectral/spatial features (discoloration, characteristic wavelength, roughness, texture, shape, etc.), extract spatial/spectral features of hyperspectral images, and develop/train a multi-class classification or regression classifier through machine learnings (supervised and/or semi-supervised), and validate ...


Webinar: Addressing Bicycle-Vehicle Conflicts With Alternate Signal Control Strategies, Sirisha Kothuri Oct 2018

Webinar: Addressing Bicycle-Vehicle Conflicts With Alternate Signal Control Strategies, Sirisha Kothuri

TREC Webinar Series

There is nationwide interest in supporting sustainable and active transportation modes such as bicycling and walking due to the many benefits associated with them, including reduced congestion, lower emissions and improved health. Although the number of bicyclists is increasing, safety remains a top concern. In urban areas, a common crash type involving bicycles at intersections is the “right hook” where a right-turning vehicle collides with a through bicyclist. While geometric treatments and pavement markings have been studied, there is a lack of research on signal timing treatments to address right-hook bicycle-vehicle conflicts.

Addressing Bicycle-Vehicle Conflicts with Alternate Signal Control Strategies ...


The Subject Librarian Newsletter, Engineering And Computer Science, Fall 2017, Buenaventura "Ven" Basco Oct 2018

The Subject Librarian Newsletter, Engineering And Computer Science, Fall 2017, Buenaventura "Ven" Basco

Buenaventura "Ven" Basco

No abstract provided.


Sensor-Enhanced Analysis And Behavior Of Steel Beams In Fire, Genda Chen Oct 2018

Sensor-Enhanced Analysis And Behavior Of Steel Beams In Fire, Genda Chen

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Traditionally, strain data are difficult, if not impossible, to obtain from steel structures in fire due to their harsh environment and temperature measurements are limited to the locations of thermocouples. This paper presents high-temperature measurements using a Brillouin scattering based (distributed) fiber optic sensor and the application of the measured temperatures and material parameters recommended in building codes into the enhanced thermo-mechanical analysis of simply-supported steel beams subjected to combined thermal and loading effects. The distributed temperature sensor captures detailed, non-uniform temperature distributions that are compared locally with thermocouple measurements by less than 5% at a 95% confidence level. The ...


Adaptive Wavelet Neural Network For Terrestrial Laser Scanner-Based Crack Detection, Yelda Turkan, Jonathan Hong, Simon Laflamme, Nisha Puri Oct 2018

Adaptive Wavelet Neural Network For Terrestrial Laser Scanner-Based Crack Detection, Yelda Turkan, Jonathan Hong, Simon Laflamme, Nisha Puri

Civil, Construction and Environmental Engineering Publications

Objective, accurate, and fast assessment of civil infrastructure conditions is critical to timely assess safety risks. Current practices rely on visual observations and manual interpretation of reports and sketches prepared by inspectors in the field, which are labor intensive, subject to personal judgment and experience, and prone to error. Terrestrial laser scanners (TLS) are promising for automatically identifying structural condition indicators, as they are capable of providing coverage for large areas with accuracy at long ranges. Major challenges in using this technology are in storing significant amount of data and extracting appropriate features enabling condition assessment. This paper proposes a ...


Experimental Tests And Numerical Simulations For Failure Investigation On Corrugated Boxes Used On Household Appliance Packaging, Diego Fernandes Rodrigues, José Carlos Pereira Sep 2018

Experimental Tests And Numerical Simulations For Failure Investigation On Corrugated Boxes Used On Household Appliance Packaging, Diego Fernandes Rodrigues, José Carlos Pereira

Journal of Applied Packaging Research

Packages made of corrugated paper are fundamental to the protection, transportation and handling of the appliance product market. During the storage and sales stages of a product, the package must resist compressive loads in different directions beyond moderate impacts. In this context, the objective of this work is to develop and implement a post-processor that allows the simultaneous analysis of two of the most common failure modes of packages made of corrugated paper: failure due to tensile or compressive stress limit, and failure due to local buckling, when the buckling of the faces of the corrugated paper between two peaks ...


A Deep Learning-Based Approach For Fault Diagnosis Of Roller Element Bearings, Mohammakazem Sadoughi, Austin Downey, Garrett Bunge, Aditya Ranawat, Chao Hu, Simon Laflamme Sep 2018

A Deep Learning-Based Approach For Fault Diagnosis Of Roller Element Bearings, Mohammakazem Sadoughi, Austin Downey, Garrett Bunge, Aditya Ranawat, Chao Hu, Simon Laflamme

Civil, Construction and Environmental Engineering Conference Presentations and Proceedings

Condition monitoring and fault detection of roller element bearings is of vital importance to ensuring safe and reliable operation of rotating machinery systems. Over the past few years, convolutional neural network (CNN) has been recognized as a useful tool for fault detection of roller element bearings. Unlike the traditional fault diagnosis approaches, CNN does not require manually extracting the fault-related features from the raw sensor data and most CNN-based fault diagnosis approaches feed the raw or shallowly pre-processed data as the training/testing inputs to a CNN model, thereby avoiding the need for manual feature extraction. As such, these approaches ...


Vertical Shear Wave Velocity Profiles Generated From Spectral Analysis Of Surface Waves: Field Examples, Neil Lennart Anderson, Genda Chen, Siasi Kociu, Ronaldo Luna, Thanop Thitimakorn, Alexi A. Malovichko, D. Malovichko, D. Shylakov Sep 2018

Vertical Shear Wave Velocity Profiles Generated From Spectral Analysis Of Surface Waves: Field Examples, Neil Lennart Anderson, Genda Chen, Siasi Kociu, Ronaldo Luna, Thanop Thitimakorn, Alexi A. Malovichko, D. Malovichko, D. Shylakov

Genda Chen

Surface wave (Rayleigh wave) seismic data were acquired at six separate bridge sites in southeast Missouri. Each acquired surface wave data set was processed (spectral analysis of surface waves; SASW) and transformed into a site-specific vertical shear-wave velocity profile (SASW shear-wave velocity profile). The SASW shear-wave velocity profiles generated for each bridge site were compared to other geotechnical data including seismic cone penetrometer shear-wave velocity profiles, cross-borehole shear-wave velocity profiles, and borehole lithology logs. The geotechnical data presented herein indicate the SASW shear-wave velocity profiles correlate well with subsurface lithology logs and available cross-borehole shear-wave velocity control. More specifically, clays ...


Unbonded Portland Cement Concrete Overlay/Pavement Monitoring With Integrated Grating And Scattering Optical Fiber Sensors, Genda Chen, Ying Huang, Yi Bao Sep 2018

Unbonded Portland Cement Concrete Overlay/Pavement Monitoring With Integrated Grating And Scattering Optical Fiber Sensors, Genda Chen, Ying Huang, Yi Bao

Genda Chen

This report summarizes the findings and results from a laboratory and field study on the strain distribution and crack development in 3" thick concrete panels cast on top of existing concrete pavements as a rapid rehabilitation strategy for roadways. Both fiber Bragg gratings (FBG) and Brillouin Optical Time Domain Reflectometry/Analysis (BOTDR/A) were applied and tested for their feasibility and effectiveness in distributed strain measurement and crack detection. For laboratory tests, six 6'×6" panels were cast similar to their corresponding field construction. Each was tested under both truck loads and under threepoint loads. The performance of distributed BOTDR ...


Temperature And Strain Measurements With Fiber Optic Sensors For Steel Beams Subjected To Fire, Yi Bao, Yizheng Chen, Matthew S. Hoehler, Christopher M. Smith, Matthew F. Bundy, Genda Chen Sep 2018

Temperature And Strain Measurements With Fiber Optic Sensors For Steel Beams Subjected To Fire, Yi Bao, Yizheng Chen, Matthew S. Hoehler, Christopher M. Smith, Matthew F. Bundy, Genda Chen

Genda Chen

This paper presents measurements of high temperatures using a Brillouin scattering based fiber optic sensor and large strains using an extrinsic Fabry-Perot interferometric sensor for assessing the thermo-mechanical behaviors of simply supported steel beams subjected to combined thermal and mechanical loading. The distributed fiber optic sensor captures detailed, non- uniform temperature distributions that are compared with thermocouple measurements resulting in an average relative difference of less than 5 % at 95 % confidence level. The extrinsic Fabry- Perot interferometric sensor captures large strains at temperatures above 1000 C. The strain results measured from the distributed fiber optic sensors and extrinsic Fabry-Perot interferometric ...


Structural Assessment Of Highway "N" Power Substation Under Earthquake Loads, Genda Chen, Dongming Yan, Zuocai Wang, Seth Justin, J. David Rogers, Kazi Rezaul Karim Sep 2018

Structural Assessment Of Highway "N" Power Substation Under Earthquake Loads, Genda Chen, Dongming Yan, Zuocai Wang, Seth Justin, J. David Rogers, Kazi Rezaul Karim

Genda Chen

In this study, the Highway N Substation was analyzed with a finite element model (FEM) for its vulnerability. The 'rigid' bus and electric switch components were characterized with full scale shake table tests. Each component of the substation was carefully modeled with due considerations of mass density, stiffness and geometries. Based on the FEM, modal analysis was conducted to identify the natural frequencies of the structure along with their corresponding mass participation factors. In response spectrum and time history analyses, the dynamic responses of main components, such as 'rigid' buses and switches, were evaluated. The magnitude and location of the ...


Strengthening Of Rural Bridges Using Rapid-Installation Frp Technology: Route 63 Bridge No. H356, Phelps County, Dongming Yan, Jianbo Li, Chenglin Bob Wu, Genda Chen Sep 2018

Strengthening Of Rural Bridges Using Rapid-Installation Frp Technology: Route 63 Bridge No. H356, Phelps County, Dongming Yan, Jianbo Li, Chenglin Bob Wu, Genda Chen

Genda Chen

This report presents the use of externally bonded fiber reinforced polymers (FRP) laminates for the flexural strengthening of a concrete bridge. The bridge selected for this project is a two-span simply supported reinforced concrete slab with no transverse steel reinforcement located in Phelps County, MO. The original construction combined with the presence of very rigid parapets caused the formation of a 1-inch wide longitudinal crack, which resulted in the slab to behave as two separate elements. The structural behavior was verified using a finite element model (FEM) of the bridge. The bridge analysis was performed for maximum loads determined in ...


Strain Distribution And Crack Detection In Concrete Overlays With Pulse Pre-Pump Brillouin Optical Time Domain Analysis, Yi Bao, Genda Chen Sep 2018

Strain Distribution And Crack Detection In Concrete Overlays With Pulse Pre-Pump Brillouin Optical Time Domain Analysis, Yi Bao, Genda Chen

Genda Chen

This report is focused on the measurement of strain distributions and crack detection in unbonded and bonded pavement overlays. The main objectives of this study are: (a) to characterize the strain sensing properties of distributed fiber optic sensors with recently developed pulse pre-pump Brillouin optical time domain analysis (PPP-BOTDA), (b) to develop an installation method for real world applications, (c) to document the performance of the PPP-BOTDA technology in unbonded/bonded pavement applications, and (d) to develop a numerical model to facilitate the analysis of mechanical behavior of unbonded pavement overlay under vehicle wheel loads. A thin concrete layer can ...


Steel Building Assessment In Post-Earthquake Fire Environments With Fiber Optical Sensors, Genda Chen, Ying Huang, Hai Xiao Sep 2018

Steel Building Assessment In Post-Earthquake Fire Environments With Fiber Optical Sensors, Genda Chen, Ying Huang, Hai Xiao

Genda Chen

No abstract provided.


Signal Mast Arm Fatigue Failure Investigation, Genda Chen, Michael G. Barker, Lokeswarappa R. Dharani, Christopher W. Ramsay Sep 2018

Signal Mast Arm Fatigue Failure Investigation, Genda Chen, Michael G. Barker, Lokeswarappa R. Dharani, Christopher W. Ramsay

Genda Chen

The Missouri Department of Transportation (MoDOT) has discovered and documented failures in several cantilever mast arms in the recent years. The failures were primarily by fatigue at the weld of the arm to the base plate attached to the mast. With over 6000 mast arms in service in Missouri, the failures raised concerns with the existing mast arm inventory and future mast arm design. This report presents findings from an effort to determine the cause of unexpected cracking in Missouri mast arms. Three causes of premature failure were investigated: the stress ranges experienced at the weld detail were higher than ...