Structural Engineering Commons^™

Review Of Fiber Optic Sensors For Structural Fire Engineering, Yi Bao, Ying Huang, Matthew S. Hoehler, Genda Chen

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Reliable and accurate measurements of temperature and strain in structures subjected to fire can be difficult to obtain using traditional sensing technologies based on electrical signals. Fiber optic sensors, which are based on light signals, solve many of the problems of monitoring structures in high temperature environments; however, they present their own challenges. This paper, which is intended for structural engineers new to fiber optic sensors, reviews various fiber optic sensors that have been used to make measurements in structure fires, including the sensing principles, fabrication, key characteristics, and recently-reported applications. Three categories of fiber optic sensors are reviewed: Grating-based …

Failure Mode Identification Of Masonry Infilled Rc Frames, Rabab Allouzi, Ayhan Irfanoglu

Emirates Journal for Engineering Research

This paper presents a new method to identify the ultimate failure mode of reinforced concrete (RC) frames due to the presence of masonry infill walls. The proposed method is based on simple geometry, reinforcement ratios and material properties of the elements involved in the frame-wall assembly. A simple engineering tool, expressed in terms of infill wall-to-RC frame stiffness and strength ratios, is developed to estimate whether the ultimate failure mode that would evolve during strong earthquake ground shaking in the infilled RC frame is brittle or ductile. The brittle failure mode, that is, shear failure in columns, should be avoided …

Inspire Newsletter Spring 2019, Missouri University Of Science And Technology. Inspire - University Transportation Center

INSPIRE Newsletters

No abstract provided.

Exploring Engineering Club, Samantha Corey, Stephen Yaghmour

Honors Program: Expanded Learning Clubs

Exploring Engineering Club provides an introduction to a variety of engineering problems and piques the students’ interest in engineering by accompanying the information with hands-on problem solving activities mainly related to structural engineering. The activities will often be done in teams which will teach good teamwork skills, as well as problem solving and critical thinking.

Seismic Performance Of Reinforced Concrete Frames Retrofitted Using External Superelastic Shape Memory Alloy Bars, Yamen Ibrahim Elbahy, Maged A. Youssef, Mohamed E. Meshaly

Civil and Environmental Engineering Publications

Pre-1970s designed and built reinforced concrete frame structures are considered unsafe when subjected to seismic loads. Insufficient anchorage of the beam reinforcement in the beam-column joints of these structures is considered a main deficiency. Newly built frame structures are seismically designed for safety, where high inelastic deformations can occur under moderate to strong earthquakes. Minimizing these inelastic deformations makes the structure repairable. One way to minimize these residual deformations is by using smart materials such as superelastic shape memory alloys (SMAs). In this paper, the seismic performance of RC frames retrofitted using external superelastic SMA bars is investigated and compared …

Design And Performance Of Fiber-Reinforced Concrete With Adapted Rheology For Construction And Repair Of Bridge Structures, Ahmed Abdelrazik

Doctoral Dissertations

“The objective of this document is to design high-performance fiber-reinforced self-consolidating concrete (FR-SCC) for infrastructure repair and fiber-reinforced super-workable concrete (FR-SWC) for bridge construction. The investigated fibers included propylene synthetic fibers, hooked steel fibers, double and triple hooked steel fibers, hybrid crimped steel fiber and polypropylene multifilament fibers, and micro-macro steel fibers. The fiber volume varied between 0 and 0.75%. An expansive agent (EA) was incorporated to compensate for shrinkage and induce compression in the concrete at early age. Two types of EA (G and K) were employed at 0 to 8%, by mass of binder. The investigated FRSCC and …

Enhanced Concrete Bridge Assessment Using Artificial Intelligence And Mixed Reality, Enes Karaaslan

Electronic Theses and Dissertations

Conventional methods for visual assessment of civil infrastructures have certain limitations, such as subjectivity of the collected data, long inspection time, and high cost of labor. Although some new technologies (i.e. robotic techniques) that are currently in practice can collect objective, quantified data, the inspector's own expertise is still critical in many instances since these technologies are not designed to work interactively with human inspector. This study aims to create a smart, human-centered method that offers significant contributions to infrastructure inspection, maintenance, management practice, and safety for the bridge owners. By developing a smart Mixed Reality (MR) framework, which can …

Development Of Poly-Vinyl Alcohol Stabilized Silver Nanofluids For Solar Thermal Applications, James Walshe, George Amarandei, Hind Ahmed, Sarah Mccormack, John Doran

Articles

Nanofluids offer the potential to address the low thermal conductivities found in conventional heat transfer fluids, through their unique electrical, optical and thermal properties, but their implementation remains restricted due to absorption and stability limitations. Here, we characterize and exploit the distinctive plasmonic properties exhibited by polyvinyl-alcohol stabilized silver nanostructures by tuning their absorption and thermal properties through controlling the nanoparticle size, morphology and particle-size distribution configuration at the synthesis stage. The photo-thermal efficiency of different water-based silver nanofluids under a standard AM1.5G weighted solar spectrum were explored, the influence of each of these components on the resulting fluids performance …

Field And Numerical Study For Deteriorating Precast Double-Tee Girder Bridges, Brian Kidd

Electronic Theses and Dissertations

Two deteriorating DT bridges in South Dakota, both over 30-years old, were field tested with a static and dynamic load. From the recorded strain values, the liveload distribution factors (LLDFs) and dynamic load allowance (IM) factors were calculated. The AASHTO LRFD and AASHTO Standard Specifications were compared with the field LLDFs and IMs. It was determined that the AASHTO LRFD Specifications were conservative for deteriorating DT girder bridges, with two exceptions. The AASHTO Standard codified LLDFs were significantly higher than the field LLDFs in all cases. The AASHTO LRFD and AASHTO Standard specifications were conservative when calculating the IM factors …

Inspire Newsletter Fall 2019, Missouri University Of Science And Technology. Inspire - University Transportation Center

INSPIRE Newsletters

No abstract provided.

Direct Determination Of The Dynamic Elastic Modulus And Poisson's Ratio Of Timoshenko Prisms And Rods, Guadalupe Leon

Graduate Theses, Dissertations, and Problem Reports (ETD)

In this study, the exact solution of the Timoshenko beam vibration frequency equation under free-free boundary conditions was determined with an accurate shear shape factor. The exact solution was compared with a 3-D finite element calculation using ABAQUS program, and the difference between the exact solution and the 3-D FEM was within 0.15% for both the transverse and torsional modes. Furthermore, relationships between the resonance frequencies and Poisson’s ratio were proposed that can directly determine the elastic constants, unlike the equations provided by ASTM C215. The frequency ratio between the 1^st bending mode and the 1^st torsional mode, …

Incorporation Of Contaminated Sediment Into Environmentally Safe Concrete, Andrew Needs

Williams Honors College, Honors Research Projects

The research performed through this project provided some interesting results on how the different properties of the contaminated sediment can impact the strength of the new concrete.

Average three, seven, and fourteen-day strengths increased when comparing to the baseline mix developed for the experiment. Increases in strengths were notices in the ten and twenty-five percent soil replacement mixes. The largest increase was approximately thirty-three percent greater than the baseline average.

The results from the forty percent replacement test showed a significant decrease in strengths when comparing against the baseline mix. A loss of about thirty percent was observed between the …

Post-Earthquake Assessment And Numerical Modeling Of Freestanding Heritage Structures, M. Khalid Saifullah, Christine E. Wittich

Department of Civil and Environmental Engineering: Faculty Publications

Historic and heritage structures are particularly vulnerable to earthquakes, where damage or collapse can not only lead to loss of a structure but also the loss of irreplaceable heritage. Many heritage structures can be classified as freestanding (detached) structures, including unreinforced masonry walls, classical multi-drum columns, and statue-pedestal systems. However, the seismic response of freestanding structures (sliding, rocking, rock-slide, overturning) is poorly predicted by existing methods due to geometric non-linearities as well as sensitivity to interface conditions and modeling parameters. Previous studies have focused on analytical modeling of simplified systems and/or experimentation under controlled laboratory conditions. In contrast, this paper …

Post-Fire Damage Geospatial Assessment Via Point Clouds Of A Highway Bridge Structure, Yijun Liao, M Ebrahim Mohammadi, Richard L. Wood, Christine E. Wittich

Department of Civil and Environmental Engineering: Faculty Publications

This paper discusses the quantitative post-fire damage assessment of a steel girder bridge via point clouds. In this case study, the point cloud was collected using light detection and ranging (lidar) for a detailed geometric and shape analysis. The out-of-plane deformation was analyzed to locate and quantify buckling across the length of the steel girders.

Efficient Intensity Measures Of Slide-Rocking Structures For Precariously Balanced Rocks, Taylor J. Knickerbocker, Christine E. Wittich

Department of Civil and Environmental Engineering: Faculty Publications

Precariously balanced rocks (PBRs) and other fragile geologic features are important in both the engineering and seismological communities since they are indicative of the maximum ground motion at a site over the rock’s lifetime. Precariously balanced rocks are individual or stacks of freestanding rocks that tend to respond in rigid body modes when subject to seismic excitation – namely, rocking, sliding, slide-rocking, and free-flight, which can lead to overturning. The seismic response of freestanding structures, such as PBRs, is known to be extremely sensitive to small changes in geometry, position, and earthquake excitation. As such, deterministic methods are limited in …

In Situ Mechanical Characterization Of The Mixed- Mode Fracture Strength Of The Cu/Si Interface For Tsv Structures, Chenglin Wu, Congjie Wei, Yanxiao Li

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In situ nanoindentation experiments have been widely adopted to characterize material behaviors of microelectronic devices. This work introduces the latest developments of nanoindentation experiments in the characterization of nonlinear material properties of 3D integrated microelectronic devices using the through-silicon via (TSV) technique. The elastic, plastic, and interfacial fracture behavior of the copper via and matrix via interface were characterized using small-scale specimens prepared with a focused ion beam (FIB) and nanoindentation experiments. A brittle interfacial fracture was found at the Cu/Si interface under mixed-mode loading with a phase angle ranging from 16.7° to 83.7°. The mixed-mode fracture strengths were extracted …

Long Period Fiber Grating, Thin Coating Of Graphene And Silver Nanowires, And Corrosion Sensing For Life-Cycle Assessment Of Steel Structures, Chuanrui Guo

Doctoral Dissertations

"This study aims to develop and validate a compact, integrated lab-on-sensor system for simultaneous measurement of strain, temperature and corrosion-induced mass loss in steel structures and concrete reinforcement elements in order to assess their life-cycle performance. The sensing system operates based on the principle of long period fiber gratings (LPFG) that are responsive to both thermal and mechanical deformation, and the change in refractive index of any medium surrounding the optical fiber. To fabricate a LPFG sensor for strain and temperature measurement, a CO₂ laser aided fiber grating system was assembled. To enable mass loss measurement, a low pressure …

Bending Response Of Timber Mortise And Tenon Joints Reinforced With Filler-Modules And Frp Gussets, Andrew Robert Pacifico

Graduate Theses, Dissertations, and Problem Reports (ETD)

In 2013, the California Bay Area (CBA) passed a set of ordinances to ensure that their 10,000 plus timber soft-story buildings were prepared for seismic events, through nondestructive evaluation methods. Many property owners are searching for an affordable retrofitting system that will also meet CBA’s new laws focusing on installations by the mandated deadlines in 2020. Over the past three to four decades, Fiber Reinforced Polymer (FRP) composites have found their way into the civil infrastructure sector for rehabilitation. The objective of this study is to evaluate the bending behavior retrofitted mortise and tenon timber joints reinforced with engineered wood …

Analysis Of Standardized Concrete Mixes, Riley Graybeal

Williams Honors College, Honors Research Projects

Concrete is one of the most common materials used in construction. It is mass produced throughout the country, with numerous different designs for concrete mixes. A common practice among concrete manufacturers is to use a standardized concrete mix design. These standardized mix designs are pre-tested and are not usually altered frequently. The hypothesis of this research project is that manufacturers do not constantly investigate new ways to save on their mixes, and simply use the same standardized mix designs.

In this research, investigations into what alterations may reduce the cost of standardized mixes began with a baseline mix design provided …

Damage Assessment Of A Sixteen Story Building Following The 2017 Central Mexico Earthquake, Yijun Liao, Richard L. Wood, M Ebrahim Mohammadi, Kanchan Devkota, Christine E. Wittich

Department of Civil and Environmental Engineering: Faculty Publications

The 2017 M7.1 Central Mexico Earthquake caused significant infrastructural damage in the Mexico City area. The earthquake contained a significant pulse in the long period, resulting in numerous buildings severely damaged or collapsed. This paper discusses a reinforced concrete building which was still partially occupied post-earthquake. The building’s interior walls were examined to have substantial damage, including some extensive cracking. In January 2018, the authors visited the structure and collected detailed assessment data. The data collection included ground-based lidar scans and recorded ambient vibrations of the damaged structure using accelerometers. Eleven scans were collected from the four exterior facades to …