Civil Engineering Commons^™

พฤติกรรมการยึดเหนี่ยวระหว่างแผ่นพอลิเมอร์เสริมเส้นใยคาร์บอนและคอนกรีตโดยใช้อีพอกซีเสริมท่อนาโนคาร์บอน, อมเรศ มธุรส

Chulalongkorn University Theses and Dissertations (Chula ETD)

งานวิจัยนี้มีวัตถุประสงค์เพื่อศึกษาพฤติกรรมการยึดเหนี่ยวระหว่างแผ่นพอลิเมอร์เสริมเส้นใยคาร์บอน (CFRP) และคอนกรีตโดยใช้อีพอกซีเสริมท่อนาโนคาร์บอน (CNTs) โดยมีตัวแปรที่ใช้ในการศึกษา คือประเภทของท่อนาโนคาร์บอน ประกอบด้วย แบบผนังชั้นเดียว (SWCNTs) และแบบผนังหลายชั้น (MWCNTs) ปริมาณของท่อนาโนคาร์บอนที่ปริมาณ 0.25, 0.50, 1.00 และ 2.00% ของปริมาณอีพอกซี และประเภทของอีพอกซี ประกอบด้วยอีพอกซีชนิดค่าความหนาแน่นเท่ากับ 1.30 และ 1.65 กิโลกรัมต่อลิตร ผลการศึกษาพบว่าพลังงานการต้านทานการแตกหักที่ผิวสัมผัสและหน่วยแรงยึดเหนี่ยวสูงสุดมีค่าเพิ่มขึ้นสูงสุด 51.11% และ 56.47% ตามลำดับ เมื่อใช้ SWCNTs ที่ 1.00% ของปริมาณอีพอกซีในอีพอกซีค่าความหนาแน่น 1.30 กิโลกรัมต่อลิตร อย่างไรก็ตามการใช้ SWCNTs และ MWCNTs เสริมอีพอกซีที่ความหนาแน่น 1.65 กิโลกรัมต่อลิตร มีแนวโน้มให้พลังงานการต้านทานการแตกหักที่ผิวสัมผัส หน่วยแรงยึดเหนี่ยวสูงสุด รวมถึงค่าการเลื่อนไถลสูงสุดที่ลดลง สำหรับรูปแบบการหลุดล่อนโดยส่วนใหญ่มีการแยกตัวที่วัสดุประสานและคอนกรีต ทั้งนี้การใช้อีพอกซีที่ความหนาแน่น 1.65 กิโลกรัมต่อลิตร โดยการใช้อีพอกซีเสริม SWCNTs ที่ปริมาณ 0.25% ของปริมาณอีพอกซี มีการหลุดล่อนจากการสูญเสียการยึดเหนี่ยวของวัสดุเชื่อมประสาน และการใช้ MWCNTs 0.25% ของปริมาณอีพอกซีมีการหลุดล่อนจากการแตกหักของคอนกรีต จากการตรวจสอบการยึดเหนี่ยวภายในชั้นของอีพอกซีและการยึดเหนี่ยวของอีพอกซีกับ CFRP ด้วยกล้องจุลทรรศน์อิเล็กตรอนแบบสแกน พบว่าให้ผลสอดคล้องกับผลของหน่วยแรงยึดเหนี่ยวสูงสุด โดยผลของชุดทดสอบที่มีหน่วยแรงยึดเหนี่ยวสูง มีลักษณะการยึดเกาะหรือการรวมตัวของอีพอกซีที่ดีและช่องว่างของอีพอกซีน้อย จึงแสดงให้เห็นถึงประสิทธิภาพของท่อนาโนคาร์บอนที่มีการปรับปรุงคุณสมบัติของอีพอกซี

Development Of Causal Relationship Model Of Knowledge Sharing In Construction Projects, Lambada Roeun

Chulalongkorn University Theses and Dissertations (Chula ETD)

Knowledge sharing among construction project members is very crucial for improving project success and project performance. It can also reduce mistakes in the construction process. Project management has been growing more complicated, and project members need to learn best practice from others. Currently, knowledge sharing is not well performed yet; especially, few research studies have been focused on the relationship evaluation of supporting factors that affect knowledge sharing from different contexts in construction projects. Therefore, this study aims to develop the causal relationship model of supporting factors from psychological, individual, organizational, and technological factors that affect mediators – knowledge sharing …

Collaborative Strategies For Sea Level Rise Adaptation In Hampton Roads, Virginia, Carol Considine, Emily Steinhilber

Engineering Technology Faculty Publications

[Introduction] The Hampton Roads region is located in southeastern Virginia where the Chesapeake Bay meets the Atlantic Ocean. The region includes seventeen municipal governments and has a large federal government presence with 26 federal agencies represented (See Figure 1). The region has a population that exceeds 1.7 million and is home to the deepest water harbor on the U.S. East Coast. Hampton Roads' economy is dependent on the local waterways and houses the world's largest naval facility, the sixth largest containerized cargo complex and supports a thriving shipbuilding and repair industry as well as a tourism industry. However, the region's …

Effect Of Vessel-Generated Waves In Near Low Tide Conditions On Shorelines In The Intracoastal Waterways, Mackenzie Lee Sanchez

UNF Graduate Theses and Dissertations

Erosion is caused when there is a net loss of sediment in a coastal system, i.e. when the amount of sediment leaving a system is more than the amount of sediment entering that same system. This investigation will focus on vessel-generated waves and their effect on the shorelines of the Jacksonville, Florida Intracoastal Waterways near low tide conditions. The investigation conducted herein examines variations in turbidity and pressure measurements in response to passing vessels at a single site location previously selected in 2016. The primary water/shoreline interaction recorded during this investigation is located below the visible scarp (near low tide …

Development Of A One-Way Coupled Diffraction/Trapped Air Model For Predicting Wave Loading On Bridge Superstructure Under Water Wave Attack, Christian Hillary Matemu

UNF Graduate Theses and Dissertations

In recent years, a number of researchers have applied various computational methods to study wind wave and tsunami forcing on bridge superstructure problems. Usually, these computational analyses rely upon application of computational fluid dynamic (CFD) codes. While CFD models may provide reasonable results, their disadvantage is that they tend to be computationally expensive. During this study, an alternative computational method was explored in which a previously-developed diffraction model was combined with a previously-developed trapped air model under worst-case wave loading conditions (i.e. when the water surface was at the same elevation as the bottom bridge chord elevation). The governing equations …

A Novel Design To Harness Water-Wave Energy, Abdallah El Safty, Abdallah Walid El Safty

UNF Graduate Theses and Dissertations

Renewable energy sources are essential to our future, not only because they generally minimize harm to our environment but are also a relatively free source of energy that are available for generations to come. Wind and solar energy are proven sources of renewable energy, but both are highly variable. On the other hand, water wave energy is relatively persistent in locations around the world. Many researchers have tried to capture the energy of ocean waves, some were successful, but most were not. Harnessing wave energy is not a simple matter. One must design systems that can withstand the extreme forces …

An Integrated Closed Convergent System For Optimal Extraction Of Head-Driven Tidal Energy, Michelle Ann Vieira

UNF Graduate Theses and Dissertations

As the demands for energy increased with the global increase in population, there is a need to create and invest in more clean and renewable energy sources. Energy derived from the movement of the tides is an ancient concept that is currently being harnessed in a handful of large tidal range locations. However, the need to move from fossil fuel driven energy sources to those that are clean and non-polluting is a priority for a sustainable future. Globally, hydropower potential is estimated to be more than 16,400-Terawatt hours annually. Given that the electricity consumption worldwide was at 15,068-Terawatt hours in …

Development Of Forward And Inversion Schemes For Cross-Borehole Ground Penetrating Radar, Donald Jones

UNF Graduate Theses and Dissertations

Tomography is an imaging technique to develop a representation of the internal features of material using a penetrating wave, such as an electromagnetic wave. The calculation method used is an example of an inverse problem, which is a system where the input and the output are known but the internal parameters are not. These parameters can be estimated by understanding the responses of a penetrating wave as it passes through the unknown media. A forward problem is just the opposite; the internal structure and input penetrating wave is known and the output is determined. For both forward and inverse problems, …

Evaluation Of The Effect Of Tack Coat Type, Application Rate, And Surface Type On Interlayer Shear Strength, Chamika Prashan Dharmarathna

Electronic Theses and Dissertations

Tack coat is an asphaltic material applied between asphalt pavement layers. Since pavement is a multilayered structure, it is highly important to make proper bond between the layers to achieve a monolithic behavior. Hence, inadequate bond due to application of inadequate amount of tack coat may lead to poor structural behavior and premature failure. Also, applying excessive amount of tack coat may lead to layer slippage and binder migration. Therefore, it is highly important to apply an optimum amount of tack coat between layers. Over the past decades several studies have been conducted to determine the optimum tack coat application …

Effect Of Pyrolysis On The Removal Of Antibiotic Resistance Genes And Class I Integrons From Municipal Wastewater Biosolids, Lee Kimbell, Anthony D. Kappell, Patrick J. Mcnamara

Civil and Environmental Engineering Faculty Research and Publications

Wastewater biosolids represent a significant reservoir of antibiotic resistance genes (ARGs). While current biosolids treatment technologies can reduce ARG levels in residual wastewater biosolids, observed removal rates vary substantially. Pyrolysis is an anoxic thermal degradation process that can be used to convert biosolids into energy rich products including py-gas and py-oil, and a beneficial soil amendment, biochar. Batch pyrolysis experiments conducted on municipal biosolids revealed that the 16S rRNA gene, the ARGs erm(B), sul1, tet(L), tet(O), and the integrase gene of class 1 integrons (intI1) were significantly reduced at pyrolysis temperatures ranging from 300–700 …

Construction Engineering Education Committee: Past, Present, And Future, Yong Bai

Civil and Environmental Engineering Faculty Research and Publications

No abstract provided.

Evaluation Of Driver Behavior At Highway-Railroad Grade Crossings Based On Environmental Conditions And Driver Demographics, Alawudin Salim

Dissertations, Master's Theses and Master's Reports

Although the total number of highway-railroad grade crossing (HRGC) accidents has significantly decreased in recent decades, they remain as one of the highest causes of injuries and fatalities in rail transportation. It is known that driver behavior is the leading cause for accidents at HRGCs, but there is less understanding on the reason for these inappropriate behaviors. This research uses the Strategic Highway Research Program 2 Naturalistic Driving Study (SHRP 2 NDS) data and a behavior scoring methodology developed at Michigan Technological University (Michigan Tech), to evaluate driver behavior when traversing HRGCs. More specifically, it uses a two-sample t-test to …

Evaluation Of Traffic Incident Timeline To Quantify The Performance Of Incident Management Strategies, Henrick Joseph Haule

UNF Graduate Theses and Dissertations

Transportation agencies are introducing new strategies and techniques that will improve traffic incident management. Apart from other indicators, agencies measure the performance of the strategies by evaluating the incidents timeline. An effective strategy has to reduce the length of the incident timeline. An incident timeline comprises various stages in the incident management procedure, starting when the incident was detected, and ending when there is the recovery of normal traffic conditions. This thesis addresses three issues that are related to the traffic incident timeline and the incident management strategies.

First, co-location of responding agencies has not been investigated as other incident …

The Role Of Wave Self-Similarity In Nearshore Wave Spectra, Morgan M. Smith

UNF Graduate Theses and Dissertations

Nonlinear wave-wave interactions and wave breaking contribute to nearshore wave energy dissipation. These factors can be analyzed by the principles of wave self-similarity. The equilibrium range can be shown in wind-driven wave spectra that exist in the form ( ) and However, the appropriate methods used to determine this loss of energy are controversial. This study examines an approach that reinvestigates the self-similarity principles. Wave spectra with lower peak periods are dominated by nonlinear wave-wave interactions which produce a scaling in shallow water. This thesis investigates the relative role of spectral similarity in different conditions in the nearshore region of …

Soil Improvement Using Microbial Induced Calcite Precipitation And Surfactant Induced Soil Strengthening, Matthew P. Davies

UNF Graduate Theses and Dissertations

Microbially induced calcite precipitation (MICP) has been used for a number of years as a technique for the improvement of various geological materials. MICP has been used in a limited capacity in organic rich soils with varying degrees of success. Investigators hypothesized that microbially-induced cementation could be improved in organic soils by using a surfactant. Varying amounts of Sodium Dodecyl Sulfate (SDS) were added to soils of varying organic content and a mixing procedure was used to treat these soils via MICP. Treated specimens were tested for unconfined compressive strength (UCS). Results appeared to show direct relationships between SDS content …

Potential Replacement Of The Us Navy's Rapid Penetration Test With The Method Of Multichannel Analysis Of Surface Waves, William Fletcher

UNF Graduate Theses and Dissertations

The United States Navy (USN) currently utilizes a Rapid Penetration Test (RPT) on both land and in water as the means to determine whether sufficient soil bearing capacity exists for piles in axial compression, prior to construction of the Elevated Causeway System (Modular) [ELCAS(M)] pile-supported pier system. The USN desires a replacement for the RPT because of issues with the method incorrectly classifying soils as well as the need to have a less labor-and-equipment-intensive method for geotechnical investigation.

The Multichannel Analysis of Surface Waves (MASW) method is selected herein as the potential replacement for the RPT. The MASW method is …

Bio-Inspired Geomaterial Improvement And Development Of Innovative Characterization Methods, Junnan Cao

Doctoral Dissertations

"This study experimentally investigated the bio-inspired improvement on geomaterials, including enzyme induced calcite precipitation (EICP) and biopolymers. This study also developed several innovative characterization tools to advance the state-of-the-art testing techniques, including SIP-BE column, rotational sedimental panel, and backpressure saturated constant hydraulic gradient break through column. Firstly, EICP test was performed on Ottawa 50-70 sand in a newly developed SIP-BE column. Nondestructive techniques -- spectral induced polarization (SIP) and bender element were used to monitor the precipitation process and shear wave velocities (V_s). SIP, V_s, and SEM results all suggest contact cementation as the preferential precipitation …

Dragline Excavation Simulation, Real-Time Terrain Recognition And Object Detection, Godfred Somua-Gyimah

Doctoral Dissertations

"The contribution of coal to global energy is expected to remain above 30% through 2030. Draglines are the preferred excavation equipment in most surface coal mines. Recently, studies toward dragline excavation efficiency have focused on two specific areas. The first area is dragline bucket studies, where the goal is to develop new designs which perform better than conventional buckets. Drawbacks in the current approach include operator inconsistencies and the inability to physically test every proposed design. Previous simulation models used Distinct Element Methods (DEM) but they over-predict excavation forces by 300% to 500%. In this study, a DEM-based simulation model …

Quantitative Phase-Field Modeling Of Crack Propagation In Multi-Phase Materials, Arezoo Emdadi

Doctoral Dissertations

”Research presented in this dissertation is focused on developing and validating a computational framework for study of crack propagation in polycrystalline composite ceramics capable of designing micro-architectures of phases to improve fracture toughness and damage tolerance of ZrB₂-based ultra-high temperature ceramics (UHTCs). A quantitative phase-field model based on the regularized formulation of Griffith’s theory is presented for crack propagation in homogenous and heterogeneous brittle materials. This model utilizes correction parameters in the total free energy functional and mechanical equilibrium equation within the crack diffusive area to ensure that the maximum stress in front of the crack tip is …

Shear Performance And Behavior Of Long Carbon Fiber Reinforced Concrete, Benjamin Paul Gliha

Doctoral Dissertations

”In this study, a laboratory testing program was developed to investigate the shear performance of fiber reinforced concrete beams. Long carbon fibers, to be included with a traditional fresh concrete mix, were developed and their shear performance was evaluated and compared to the performance and behavior of unreinforced concrete, traditionally reinforced concrete, and fiber reinforced concrete (FRC) with other fiber types.

The experimental program consisted of 30 large-scale beams tested for shear performance under monotonic loading. In addition to the large-scale beams, small-scale specimens were constructed of the same materials to correlate large-scale performances to ASTM C1609 testing and to …