Civil and Environmental Engineering Commons^™

Performance Of Frp-Retrofitted Concrete Bridge Columns Under Blast Loading, R. Zheng, P. Zohrevand, H. Erdogan, Amir Mirmiran

Civil Engineering Faculty Publications and Presentations

Contrary to military or essential government buildings, most bridges are designed without any consideration for blast resistance. Fiber-reinforced polymers (FRPs) can provide an effective means for strengthening of critical bridges against such loading. This study has focused on the effectiveness of FRP retrofitting in the dynamic response of reinforced concrete bridge columns under blast loading. Using a simplified equivalent I-section with a virtual material lumped at the two flanges; a lightly meshed uniaxial finite element model was developed and successfully validated against previous studies. The proposed model was then used for a thorough parametric study on the blast resistance of …

Using A Centrifuge For Quality Control Of Pre-Wetted Lightweight Aggregate In Internally Cured Concrete, Albert E. Miller

Open Access Theses

Early age shrinkage of cementitious systems can result in an increased potential for cracking which can lead to a reduction in service life. Early age shrinkage cracking can be particularly problematic for high strength concretes, which are often specified due to their high strength and low permeability. However, these high strength concretes frequently exhibit a reduction in the internal relative humidity (RH) due to the hydration reaction (chemical shrinkage) and self-desiccation which results in a bulk shrinkage, termed autogenous shrinkage, which is substantial at early ages. Due to the low permeability of these concretes, standard external curing is not always …

Heat Transfer Characteristics Of Ggbs Concrete In Fire, Ted Mckenna, Mark G. Richardson, Brian O’Rourke

Publications

Partial replacement of high clinker content cements by Ground Granulated Blastfurnace Slag (GGBS) can reduce the carbon footprint of concrete, with consequent benefits in respect of sustainable construction. Furthermore a state-of-the-art report indicated that use of GGBS as a binder replacement may increase the fire resistance of concrete. If so this could lead to thinner sections in fire compartment elements, especially non-loadbearing walls, leading to further gains in respect of sustainable development. Concrete is considered an effective material in protecting against the detrimental effects of fire in structures. However, exposure to high temperatures can degrade concrete performance. Fire resistance performance …

Transport Properties Of Nano-Silica Contained Self-Consolidating Concrete, Borhan Moradi

UNLV Theses, Dissertations, Professional Papers, and Capstones

In this research study, transport properties of various self-consolidating concretes (SCCs) containing nano-particles (SiO2) were investigated. Nano-silica replaced a portion of the cementitious materials at different replacement levels ranging from 1.5 to 7.5% by weight. For the purpose of this investigation, flow, bulk, and transport properties of SCCs were studied. The investigated transport properties were absorption, water penetration, rapid chloride permeability, capillary absorption, rapid migration, and chloride diffusion. Transport properties of nano-silica SCCs were also compared to those of equivalent silica fume (micro silica) contained concretes, as well as those of control mixture (concrete without nano or micro silica).

Test …

Application Of Bamboo For Flexural And Shear Reinforcement In Concrete Beams, Nathan Schneider

All Theses

As the developing world is industrializing and people migrate to cities, the need for infrastructure is growing quickly and concrete has become one of the most widely used construction materials. One poor construction practice observed widely across the developing world is the minimal use of reinforcement for concrete structures due to the high cost of steel. As a low-cost, high-performance material with good mechanical properties, bamboo has been investigated as an alternative to steel for reinforcing concrete. The goal of this research is to add to the knowledge base of bamboo reinforced concrete (BRC) by investigating a unique stirrup design …

Influence Of Fly Ash On Surface Chloride Concentration Under Shallow Immersion Condition, Jun Liu, Xiaodong Wang, Feng Xing, Ningxu Han

International Conference on Durability of Concrete Structures

In this paper, the influence of fly ash content on concrete surface chloride concentration was investigated through periodical tests of surface chloride concentration of concrete by immersing three kinds of concrete specimens in 5.0 wt.% sodium chloride solution. One kind of specimen is common concrete without fly ash, whereas the other two kinds of specimens are mixed with fly ash. The results show that the surface chloride ion concentration ranges from 0.295 to 0.777 wt.% for the immersed concrete samples in this study; in the initial stage of immersion, the concrete surface chloride ion concentration is affected by added fly …

Failure Mechanisms And Key Parameters Of Frp Debonding From Cracked Concrete Beams, Tayyebeh Mohammadi

Dissertations (1934 -)

Intermediate crack (IC) induced debonding failure of Fiber Reinforced Polymer (FRP)-strengthened reinforced concrete beams starts at the tip of flexural/shear cracks within the shear span and propagates towards the FRP plate termination. In this study, experimental and numerical programs are performed to characterize and predict the failure mechanisms of IC debonding failure, and identify the key parameters affecting such failure. It is found that the bond-slip relation obtained from the pullout test does not represent the bond-slip relation of the FRP/concrete interface in the FRP-strengthened concrete beams, and it cannot be directly used for predicting the load capacity of the …

A Critical Review Of Research On Reuse Of Mechanically Recycled Frp Production And End-Of-Life Waste For Construction, Ardavan Yazdanbakhsh, Lawrence C. Bank

Publications and Research

For the last three decades, fiber reinforced polymer (FRP) composite materials have been widely used in major engineering industries. Managing FRP waste is becoming an important issue due to the growth in the production of FRP composite materials. In this article, the issue of FRP waste management is discussed and the commonly used methods for the handling of FRP waste are reviewed. One potentially viable use of FRP waste is in the partial replacement of fillers or aggregates in cementitious materials (particularly portland cement mortar and concrete). A number of important prior investigations performed on the use of FRP waste …

Electrochemical-Mechanistic Model For Concrete Cover Cracking Due To Corrosion Initiated By Chloride Diffusion, Goli Nossoni, Ronald S. Harichandran

Civil Engineering Faculty Publications

A holistic electrochemical-mechanistic model of the corrosion of steel reinforcing bars inside concrete that accounts for the diffusion of oxygen and moisture into the concrete and rust layers, the densification of rust due to confinement, the flow of rust into the concrete pores, the development of internal pressure due to rust buildup, and cracking of the concrete cover is presented. The relationship between the corrosion current and the pressure buildup due to the corrosion products for different concrete cover thicknesses and concrete quality was calibrated through experiments using an accelerated corrosion test with an applied current. Results from finite-element analysis …

Retrofitting Of Shear-Deficient Reinforced Concrete T-Girders With Composite-Based Systems, Alaa Ahmad Ata Maali

Theses

This research examines the viability of using different composite-based systems to upgrade the shear resistance of shear-deficient reinforced concrete T-girders. The research comprised experimental testing and analytical investigation. Test parameters included the retrofitting system; externally-bonded carbon fiber-reinforced polymer (EB-CFRP) laminates with or without a mechanical end anchorage (MA) and embedded through depth glass fiber-reinforced (ETD-GFRP) rebars; amount of internal stirrups; no stirrups, limited amount of stirrups with spacing s₁ = 0.6d, higher amount of stirrups with spacing s₂ = 0.375d; and initial shear damage prior to retrofitting; no damage, pre-cracking, and pre-failure.

The shear …

Flexural Behavior Of Reinforced Concrete T-Beams Strengthened With Nsm Composite System Under Accelerated Corrosion., Anes Bouchair

Theses

This research work aims at evaluating the effects of corrosion on flexural response of simply supported reinforced concrete (RC) T-Beams strengthened with near-surface-mounted carbon fiber-reinforced polymer (NSM-CFRP) strips. The research comprised experimental testing and analytical modelling. Test parameters included concrete grade, amount of NSM-CFRP strips, presence of U-wraps along the beam span, and time of corrosion exposure. A total of eighteen reinforced concrete beams with a T-shaped cross section were tested. Fourteen beams were strengthened in flexure and four beams were not strengthened to act as benchmarks. The strengthening regime included installation of either two or four NSM-CFRP strips into …

Reliability Analysis For Shear In Lightweight Reinforced Concrete Bridges Using Shear Beam Database, Danile F. Jensen

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

The objective of this report is to analyze and calibrate the reliability indices for shear in reinforced concrete bridge girders. Existing statistical models are based on limited experimental data from only a few research tests. These existing models show that our current procedures for analysis are about 10-15% less conservative for lightweight concrete compared to an analysis for normal weight concrete. Accurate load models are used to find shear and moment envelopes of loads applied to bridges. Analysis is based on different span lengths, span number and girder dimensions. Design calculations are performed using design values and loads calculated from …

Uniform Temperature Predictions And Temperature Gradient Effects On I-Girder And Box Girder Concrete Bridges, Edyson Rojas

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The Federal Highway Administration (FHWA) created the Long-Term Bridge Performance (LTBP) program with the objective of acquiring quality scientific data for in-service bridge performance throughout the United States. This information will be used to improve the practices of bridge design and maintenance. To accomplish this objective, a variety of sensors were installed on a bridge south of Sacramento, California and a bridge near Perry, Utah. Data from the sensors is constantly gather and analyzed.

This research analyzed the data from the temperature sensors in order to investigate the effect of temperature changes in the California and Utah bridges over a …

Benefits Of Geopolymer Concrete-Filled Frp Beams And Its Flexural Behavior, Wahid Ferdous, Allan Manalo, Amar Khennane, Obada Kayali

Wahid Ferdous

Thin Conductive Concrete Overlay For Bridge Deck Deicing And Anti-Icing, Sherif Yehia, Christopher Tuan

Christopher Y. Tuan

Concrete bridge decks are prone to ice accumulation. Bridge decks freeze before the roads approaching them freeze, making wintry highway travel treacherous. Road salts and deicing chemicals are effective for ice removal but cause damage to concrete and corrosion of reinforcing steel in concrete bridge decks. The resulting rapid degradation of existing concrete pavements and bridge decks is a major concern to transportation and public-works officials. The use of insulation materials for ice control and electric or thermal heating for deicing have been attempted, with unsatisfactory results. Conductive concrete is a cementitious admixture containing electrically conductive components to attain high …

Flexural Behavior Of Concrete-Filled Circular Steel Tubes Under High-Strain Rate Impact Loading, Yaohua Deng, Christopher Tuan

Christopher Y. Tuan

Nine simply supported circular steel concrete-filled tubes (CFTs), two circular steel posttensioned concrete-filled tubes (PTCFTs), and one circular steel fiber–reinforced concrete-filled tube (FRCFT) have been tested in an instrumented drop-weight impact facility. The weight and the height of the drop-weight were varied to cause failure in some test specimens. The failure modes and local damages in those specimens have been investigated extensively. Failure in the steel tubes was commonly tensile facture or rupture along the circumference. Concrete core in the impact area commonly crushed under compression and cracked under tension. The use of prestressing strands and steel fibers significantly restrained …

Conductive-Concrete Overlays - An Innovative Solution For Bridge Deck Deicing, Sherif Yehia, Christopher Tuan

Christopher Y. Tuan

Bridge decks are prone to ice accumulation, making winter travel treacherous. Road salts and some other deicing chemicals are cost effective, but may cause surface scaling, reinforcing-steel corrosion, or both. Another alternative is a thin, conductive-concrete overlay that, when connected to a power source, can generate enough heat through electrical resistance to prevent ice formation on the deck or melt ice after it forms. Using a conductive concrete overlay provides an environment-friendly deicing method that would prolong bridge service life by significantly reducing the use of road salt and deicing chemicals. When used on pedestrian bridges, sidewalks, and driveways, it …

Evaluation Of Use Of Lithium Nitrate In Controlling Alkali-Silica Reactivity In Existing Concrete Pavement, Christopher Tuan, Hoasu Sun

Christopher Y. Tuan

This study presents the findings from a 2-year field trial in which lithium nitrate was applied at a rate of 0.006 gal/ft2 twice a year on an existing concrete pavement in Norfolk, Nebraska, in an attempt to arrest ongoing alkali-silica reaction (ASR) distress. Various destructive and nondestructive means were used to measure the effectiveness of the treatments. Concrete cylinders were cored for petrographic examination and split tension testing. Powder samples were taken to determine the lithium content. Nondestructive evaluations used crack mapping, a Schmidt hammer, a velocity meter, and an impact echo apparatus. The amount of lithium that penetrated into …

Electrical Resistance Heating Of Conductive Concrete Containing Steel Fibers And Shavings, Christopher Tuan

Christopher Y. Tuan

Conductive concrete is a category of concrete containing electrically conductive components to attain stable and high electrical conductivity. Due to its electrical resistance and impedance, a thin conductive concrete overlay can generate enough heat to prevent ice formation on a bridge deck when connected to a power source. Steel fibers and steel shavings were used for the conductive materials in this study. A conventional concrete slab, 1.2 x 3.6 m (4 x 12 ft), has been constructed with a 9 cm (3.5 in.) conductive concrete overlay for conducting deicing experiments in the natural environment. The conductive concrete mixture was developed …

Implementation And Field Testing Of Improved Bridge Parapet Designs, Amy E. Kalabon

ETD Archive

Premature cracking of concrete bridge parapets is a potentially complex problem, with a number of possible causes. Identifying the cause of premature cracking, and avoiding this problem in the future has several benefits, including: a potential cost savings for the district, improving the safety of these structures in future construction, and increasing the overall understanding of parapets. The objective of this study was to analyze the reasons for uncontrolled cracking in order to establish an improved parapet design, and provide recommendations to the Ohio Transportation (ODOT) to prevent such cracking in the future. Previous research carried out a forensic investigation …

Selection Of High Performance Repair Materials For Pavements And Bridge Decks, Alice E. Sommerville

ETD Archive

The Ohio Transportation has identified the need to specify durable, more permanent high performing pavement and bridge deck patching materials. These materials need to allow for expedited pavement and bridge deck wearing surface repair for worker and user safety. Currently, either temporary or generally specified in-kind or like materials are being used to perform pavement patching. Usually, the Department provides generically specified cementitious or cold mix asphalt materials for patching wearing surfaces with varied performance characteristics. Current products used for these repairs are generally those that have been used for many decades for which competition exists. However, new or proprietary …

Study On Surface Permeability Of Concrete Under Immersion, Jun Liu, Feng Xing, Biqin Dong, Hongyan Ma, Dong Pan

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In this paper, concrete specimens are immersed in ultrapure water, to study the evolutions of surface permeability, pore structure and paste microstructure following the prolonging of immersion period. According to the results, after 30-day immersion, the surface permeability of concrete becomes higher as compared with the value before immersion. However, further immersion makes the surface permeability decrease, so that the value measured after 150-day immersion is only half that measured after 30-day immersion. The early increase in surface permeability should be mainly attributed to the leaching of calcium hydroxide, while the later decrease to the refinement of pore structure due …

Mechanical And Transport Properties Of Alkali-Activated Natural Pozzolans As Sustainable Binders, Brittany Radke

Calvert Undergraduate Research Awards

OPC production accounts for 5 to 7% of the global carbon dioxide (CO₂) emissions, contributing to global warming. The desire to reduce CO₂ emissions and produce more durable concrete has given impetus to search for new binders. It is suggested that alkali-activated natural pozzolans have the potential for use as a sustainable replacement for OPC in concrete.

The current study presented herein evaluated fresh, mechanical, and transport properties of alkali-activated natural pozzolan mortars containing various concentrations of sodium hydroxide solutions as an alkaline activator. To this aim, alkali-activated natural pozzolan mortars were made with concentrations of sodium …

Agricultural Wastes As Aggregate In Concrete Mixtures – A Review, Hilmi Mahmud

Hilmi Mahmud

Concrete is the most widely used construction material. With the ever-increasing industrialization and urbanization, huge amounts of natural resources are required to make concrete. This, in turn, means that large volumes of natural resources and raw materials are being used for concrete production around the world. To eliminate or minimize the negative environmental impact of the concrete industry and promote environmental sustainability of the industry, the use of wastes from industry as materials for concrete making is considered as an alternative solution for preventing the excessive usage of raw materials. The wide availability of agricultural wastes make them a suitable …