Engineering Commons^™

From Superhydrophilicity To Superhydrophobicity: High-Resolution Neutron Imaging And Modeling Of Water Imbibition Through Porous Surfaces Treated With Engineered Nano-Coatings, Filip Zemajtis, Abul Borkot Md Rafiqul Hasan, Ohan Yetik, Pavel Trtik, Krishna M. Pillai, Konstantin Sobolev

Civil and Environmental Engineering Faculty Articles

This paper reports on a superhydrophilic to superhydrophobic transformation of TiO2 nanoparticles doped zinc phosphate coating systems when a hydrophobic agent is applied. The objective of the reported research was to demonstrate the feasibility of a neutron imaging technique for evaluating the performance of the proposed nano-coating system and reveal the differences in water ingress mechanisms which are specific to plain, superhydrophilic, overhydrophobic, and superhydrophobic specimens. The engineered nano-coatings were designed to improve hydrophobic response with inducing the required roughness pattern and introducing the photocatalytic performance. The effectiveness of the coatings was assessed using high-resolution neutron imaging (HR-NI), SEM, CLSM, …

An Energy Dissipating Seismic Connector For Precast Concrete Shear Walls, Mohammed Aljuboori, Habib Tabatabai

Civil and Environmental Engineering Faculty Articles

In this study, several steel connector shapes were analytically evaluated as potential new seismic energy dissipating devices between vertical precast concrete shear wall panels. Based on the results of analytical and experimental studies, a multiple yield zone (MYZ) connector is proposed due to its improved performance (in energy dissipation) when compared to the conventional U-shaped flexure plate (UFP) device. Unlike the UFP, the MYZ connector provides stiffness and energy dissipation in both horizontal and vertical directions. The response of a shear wall building system utilizing the MYZ or UFP connectors was evaluated using a simplified frame model. The MYZ connector …

Stress Change Calculations In Accidentally Damaged Prestressed Bridge Girders, Habib Tabatabai, Azam Nabizadeh

Civil and Environmental Engineering Faculty Articles

Accidental damage to prestressed concrete bridge girders may occur due to impact by over-height vehicles on the bottom of the girder, or the top flange of the girder may be damaged during deck removal and replacement operations. Since stress checks at service loads are an important component of design for prestressed concrete beams, serviceability-based stress checks should be considered when assessing the structural condition of damaged girders. In this paper, step-by-step theoretical calculations are used to develop equations for estimating service load stress changes due to physical damage (partial loss of concrete section and strands) based on a differential approach. …

Electrospinning Processing Techniques For The Manufacturing Of Composite Dielectric Elastomer Fibers, Rani Elhajjar

Civil and Environmental Engineering Faculty Articles

Dielectric elastomers (DE) are novel composite architectures capable of large actuation strains and the ability to be formed into a variety of actuator configurations. However, the high voltage requirement of DE actuators limits their applications for a variety of applications. Fiber actuators composed of DE fibers are particularly attractive as they can be formed into artificial muscle architectures. The interest in manufacturing micro or nanoscale DE fibers is increasing due to the possible applications in tissue engineering, filtration, drug delivery, catalysis, protective textiles, and sensors. Drawing, self-assembly, template-direct synthesis, and electrospinning processing have been explored to manufacture these fibers. Electrospinning …

Polymer Geogrids: A Review Of Material, Design And Structure Relationships, Rani Elhajjar

Civil and Environmental Engineering Faculty Articles

Geogrids are a class of geosynthetic materials made of polymer materials with widespread transportation, infrastructure, and structural applications. Geogrids are now routinely used in soil stabilization applications ranging from reinforcing walls to soil reinforcement below grade or embankments with increased potential for remote-sensing applications. Developments in manufacturing procedures have allowed new geogrid designs to be fabricated in various forms of uniaxial, biaxial, and triaxial configurations. The design flexibility allows deployments based on the load-carrying capacity desired, where biaxial geogrids may be incorporated when loads are applied in both the principal directions. On the other hand, uniaxial geogrids provide higher strength …

Novel Adhesive Anchoring System Through Engineered Interface, Hua Liu, Jian Zhao

Civil and Environmental Engineering Faculty Articles

This report describes a study of an innovative adhesive anchoring system. The weak link in the load transferring path of adhesive anchors is at adhesive-concrete (A-C) interface; hence, the innovation is about creating threads/grooves in drilled holes in concrete before the holes are filled with adhesive and anchors are installed. The new anchoring system is expected to improve the robustness of A-C interface and the consistence of adhesive anchors.

The new adhesive anchoring system was verified in this study using both unconfined and confined pullout tests in uncracked concrete. The tests were divided into to two groups, one using traditional …

Impact Of Test Setup On Tensile Behavior Of Adhesive Anchors, Da Luo, Hua Liu, Jian Zhao

Civil and Environmental Engineering Faculty Articles

This report describes a study of adhesive anchors in two types of tension tests. Confined tension (CT) tests are relatively easy to implement; however, the closely placed reaction may create undesirable and unrealistic confining condition to test anchor. Unconfined tension (UCT) tests are then needed to verify the tensile capacities, which usually correspond to lower bond strength than those from CT tests. Therefore, bond strengths obtained from CT tests must be reduced, and a reduction factor of 0.75 has been stipulated in ACI 355.4 document. This reduction factor (alpha_setup) is currently being challenged.

In this study, we attempt to explore …

Calculation Of Exposed Length Of Anchor Bolts In Shear I: Monotonic Loading, Da Luo, Jian Zhao

Civil and Environmental Engineering Faculty Articles

This report describes a study of stand-off anchors in shear with various exposed lengths. Anchor bolts embedded in concrete are commonly used in construction, and often leveling nuts are used to adjust the position of attached steel components. In this case, a portion of anchor bolts may be exposed as in a typical column footing connection without grouting. Such anchor bolts in shear are subjected to combined bending, shear and tension depending upon the stand-off heights, concrete compressive strength, and anchor diameter. The shear capacity of exposed anchors is critically related to the total exposed length, including the stand-off height …

Quantitative Peel Test For Thin Films/Layers Based On A Coupled Parametric And Statistical Study, Maysam Rezaee, Li Chih Tsai, Muhammad Istiaque Haider, Armin Yazdi, Ehsan Sanatizadeh, Nathan P. Salowitz

Mechanical Engineering Faculty Articles

The adhesion strength of thin films is critical to the durability of micro and nanofabricated devices. However, current testing methods are imprecise and do not produce quantitative results necessary for design specifications. The most common testing methods involve the manual application and removal of unspecified tape. This overcome many of the challenges of connecting to thin films to test their adhesion properties but different tapes, variation in manual application, and poorly controlled removal of tape can result in wide variation in resultant forces. Furthermore, the most common tests result in a qualitative ranking of film survival, not a measurement with …

Conditional Survival Analysis For Concrete Bridge Decks, Azam Nabizadeh, Habib Tabatabai, Mohammad A. Tabatabai

Civil and Environmental Engineering Faculty Articles

Bridge decks are a significant factor in the deterioration of bridges, and substantially affect long-term bridge maintenance decisions. In this study, conditional survival (reliability) analysis techniques are applied to bridge decks to evaluate the age at the end of service life using the National Bridge Inventory records. As bridge decks age, the probability of survival and the expected service life would change. The additional knowledge gained from the fact that a bridge deck has already survived a specific number of years alters (increases) the original probability of survival at subsequent years based on the conditional probability theory. The conditional expected …

Improved Antibacterial Performance Using Hydrogel-Immobilized Lysozyme As A Catalyst In Water, Yuemei Ye, Stanislav Klimchuk, Mingwei Shang, Junjie Niu

Materials Science & Engineering Faculty Articles

Silver nanoparticle-based catalysts are used extensively to kill bacteria in drinking water treatment. However secondary contamination and their high cost require scientists to seek alternatives with non-toxicity, high activity and low cost. In this article, we develop a new hydrogel-immobilized lysozyme (h-lysozyme) that shows excellent antibacterial performance, including high activity duration of up to 55 days, inhibition efficiency as high as 99.4%, good recycling capability of up to 11 cycles, a wide temperature window and extremely low concentration. The immobilized lysozyme displayed greatly improved bacterial inhibition with both Gram-negative E. coli and Gram-positive B. subtilis, which enables broad antibacterial …

Long Term Performance Of Gravel Base Course Layers In Asphalt, Hani H. Titi, Mahmoud Dakwar, Mohammad Sooman, Habib Tabatabai

Civil and Environmental Engineering Faculty Articles

This research investigated the performance of base layer aggregates in HMA pavements using laboratory tests (standard compaction, particle size analysis, Atterberg Limits, sodium sulfate soundness, Micro-Deval abrasion, absorption, specific gravity, and soaked CBR) on existing base layer materials as well as pavement surface visual and automated distress surveys. The purpose of this research was to investigate potential degradation of aggregate bases, strength variations over time, and the likely causes for both. Analysis of laboratory and field test results indicated significant variability in the properties and characteristics of base layer aggregate materials in various pavement test sections. Based on the results …

A Hierarchical, Fuzzy Inference Approach To Data Filtration And Feature Prioritization In The Connected Manufacturing Enterprise, Phillip M. Lacasse, Wilkistar Otieno, Francisco P. Maturana

Industrial & Manufacturing Engineering Faculty Articles

In manufacturing, the technology to capture and store large volumes of data developed earlier and faster than corresponding capabilities to analyze, interpret, and apply it. The result for many manufacturers is a collection of unanalyzed data and uncertainty with respect to where to begin. This paper examines big data as both an enabler and a challenge for the connected manufacturing enterprise and presents a framework that sequentially tests and selects independent variables for training applied machine learning models. Unsuitable features are discarded, and each remaining feature receives a crisp numeric output and a linguistic label, both of which are measures …

Ultrasonic Sensing And Actuation In Laminate Structures Using Bondline-Embedded D35 Piezoelectric Sensors, Hussain Ahmed Altammar, Anoop K. Dhingra, Nathan P. Salowitz

Mechanical Engineering Faculty Articles

Ultrasonic systems employing embedded piezoelectric transducers have seen increased interest in recent years. The ability to sense, actuate, and analyze the wave propagation modes in engineering structures has been fundamental to the advancement of ultrasonic structural health monitoring (SHM). This paper presents a study into the sensing and actuation properties of shear-mode (d35) piezoelectric transducers made of lead zirconate titanate (PZT) that are internally embedded in the bondline of laminate structures. The manuscript presents analytical analysis, finite element simulation, and experimental validation building from an individual piezoelectric element to a full laminate structure. The validated model was then used to …

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 …

Novel Robust Control Of A 7-Dof Exoskeleton Robot, Mehran Rahmani, Mohammad Habib Rahman

Mechanical Engineering Faculty Articles

This paper proposes a novel robust control method for the control of a 7-DOF exoskeleton robot. The external disturbances and unknown dynamics in the form of friction forces, different upper-limb's mass, backlash, and input saturation make robot unstable, which prevents the robot from correctly following the defined path. A new fractional sliding mode controller (NFSMC) is designed, which is robust against unknown dynamic and external disturbances. Fractional PID controller (FPID) has high trajectory tracking, but it is not robust against external disturbances. Therefore, by combining NFSMC and FPID controllers, a new compound fractional PID sliding mode controller (NCFPIDSMC) is proposed, …

Application Of Sharp- And Diffuse-Front Models For Predicting Mass Gain And Saturation In Fibrous Wicks, Amin Zarandi, Krishna M. Pillai

Mechanical Engineering Faculty Articles

Wicking as imbibitional flow of a liquid driven by capillary pressure has been an important topic in different areas from simple applications like air refreshers and lightening torches to high-tech one such as Propellant Management Devices (PMD)[1, 2]. In this research, wicking of a liquid into porous wicks made parallel fibers is investigated. In the first step, we developed a model for predicting the height of liquid front during the wicking process as a function of time using Darcy’s law based on the assumption of single-phase flow behind a clear sharp front. Then the theoretically developed model was evaluated by …

Solar Radiation Parameters For Assessing Temperature Distributions On Bridge Cross-Sections, Junqing Xue, Jianhui Lin, Bruno Briseghella, Habib Tabatabai, Baochun Chen

Civil and Environmental Engineering Faculty Articles

Solar radiation is one of the most important factors influencing the temperature distribution on bridge girder cross-sections. The bridge temperature distribution can be estimated using estimation models that incorporate solar radiation data; however, such data could be cost- or time-prohibitive to obtain. A review of literature was carried out on estimation models for solar radiation parameters, including the global solar radiation, beam solar radiation and diffuse solar radiation. Solar radiation data from eight cities in Fujian Province in southeastern China were obtained on site. Solar radiation models applicable to Fujian, China were proposed and verified using the measured data. The …

Residual Tensile Strength And Bond Properties Of Gfrp Bars After Exposure To Elevated Temperatures, Devon S. Ellis, Habib Tabatabai, Azam Nabizadeh

Civil and Environmental Engineering Faculty Articles

The use of fiber reinforced polymer (FRP) bars in reinforced concrete members enhances corrosion resistance when compared to traditional steel reinforcing bars. Although there is ample research available on the behavior of FRP bars and concrete members reinforced with FRP bars under elevated temperatures (due to fire), there is little published information available on their post-fire residual load capacity. This paper reports residual tensile strength, modulus of elasticity, and bond strength (to concrete) of glass fiber reinforced polymer (GFRP) bars after exposure to elevated temperatures of up to 400 C and subsequent cooling to an ambient temperature. The results showed …

A Novel Concrete-Based Sensor For Detection Of Ice And Water On Roads And Bridges, Habib Tabatabai, Mohammed Aljuboori

Civil and Environmental Engineering Faculty Articles

Hundreds of people are killed or injured annually in the United States in accidents related to ice formation on roadways and bridge decks. In this paper, a novel embedded sensor system is proposed for the detection of black ice as well as wet, dry and frozen pavement conditions on roads, runways, and bridges. The proposed sensor works by detecting changes in electrical resistance between two sets of stainless steel poles embedded in the concrete sensor to assess surface and near-surface conditions. A preliminary decision algorithm is developed that utilizes sensor outputs indicating resistance changes and surface temperature. The sensor consists …

Criteria And Practices Of Various States For The Design Of Jointless And Integral Abutment Bridges, Habib Tabatabai, Hassan Magbool, Ahmed Bahumdain, Cui Fu

Civil and Environmental Engineering Faculty Articles

The design of integral abutment bridges is not explicitly addressed in the U.S. bridge design specifications. Despite the lack of a specific national design standard for such bridges, their usage has grown steadily since several states began experimenting with this type of structure in the 1980s. The primary objective of the work reported here was to understand and compare the current (2017) design criteria and parameters that are being utilized by various states for the design of jointless and integral abutment bridges. In this paper, the required information was sought by obtaining all publicly-available “bridge design manuals” that are commonly …

Self-Assembled Levitating Clusters Of Water Droplets: Pattern-Formation And Stability, Alexander A. Fedorets, Mark Frenkel, Evgeny Shulzinger, Leonid A. Dombrovsky, Edward Bormashenko, Michael Nosonovsky

Mechanical Engineering Faculty Articles

Water forms ordered hexagonally symmetric structures (snow crystals) in its solid state, however not as liquid. Typically, mists and clouds are composed of randomly moving small droplets lacking any ordered structure. Self-organized hexagonally patterned microdroplet clusters over locally heated water surfaces have been recently observed. However, many aspects of the phenomenon are far from being well understood including what determines droplets size, arrangement, and the distance between them. Here we show that the Voronoi entropy of the cluster tends to decrease indicating to their selforganization, while coupling of thermal effects and mechanical forces controls the stability of the clusters. We …

Darcy's Law-Based Model For Predicting Wicking Of Liquids In Glass-Fiber Wicks, Mohammad Amin Faghihi Zarandi, Krishna M. Pillai, Adam Kimmel

Mechanical Engineering Faculty Articles

Spontaneous imbibition of liquids in glass-fiber wicks, where a liquid-front progresses during the wicknig process, is investigated experimentally and modeled using the concepts of single-phase flow in porous media. In order to have an accurate validation of the proposed model, a well-characterized glass-fiber wick and wicking liquid are used to plot the liquid-front of absorbed liquid as a function of time. The experimental outcomes are fcompared with predictions by the proposed analytical solution obtained by combining Darcy's law with the continuity equation and a capillary (suction) pressure formula imposed on the liquid front. The theoretical permeability and capillary-pressure formula used …

Survival Analyses For Bridge Decks In Northern United States, Habib Tabatabai, Chin-Wei Lee, Mohammad A. Tabatabai

Civil and Environmental Engineering Faculty Articles

The use of deicing salts in northern regions of the United States is a major contributor to the long-term deterioration of bridge decks. In this study, the 2008 U.S. National Bridge Inventory (NBI) records were used to develop survival models for non-reconstructed bridge decks in six northern states of Minnesota, Wisconsin, Michigan, Ohio, Pennsylvania, and New York. The hypertabastic accelerated failure model was used to develop survival (reliability) and hazard (failure rate) functions for all six states. The NBI parameters included were the deck rating, type of superstructure (concrete or steel), deck surface area, age, and average daily traffic (ADT). …

Design Considerations For Integral Abutment/ Jointless Bridges In The Usa, Ralph G. Oesterle, Habib Tabatabai

Civil and Environmental Engineering Faculty Articles

This paper summarizes results of a major study on jointless bridges sponsored by the U.S. Federal Highway Administration. This study included extensive laboratory and field experiments as well as detailed analytical studies. A set of design recommendations were provided. Jointless bridges have reduced maintenance, improved riding quality, lower impact loads, reduced snowplow damage, and structural continuity for live load and seismic resistance. However, the thermal movements of the bridge and restraint forces from the abutments and piers must be considered and accommodated. The general design philosophy is to build flexibility into the support structures to the extent feasible while providing …