Engineering Commons^™

Investigation Of Wide Beam And Interfacial Shear Transfer In Reinforced Concrete Structures, Nikkolas Edgmond

Doctoral Dissertations

"The use of reinforced concrete (RC) allows for unique designs of structural elements and connections because of the ability to vary the geometry and reinforcement detailing with ease. However, this freedom in the design process can lead to specialized conditions that have not been extensively studied by means of experimental testing. This is especially true for components or regions of components that are subjected to high shear loads, which are susceptible to undesirable and brittle failures. While many studies have been conducted to investigate the shear behavior of RC structural members and components to determine the critical design parameters, these …

Implementation Of Ground Penetrating Radar (Gpr) And Complementary Non-Destructive Testing On Concrete Structures, Macy Spears

Electronic Theses and Dissertations

This study analyzes the application and practicality of different non-destructive testing (NDT) methods for the inspection of reinforced concrete. There are two studies discussed in this paper. The first one is a laboratory investigation, utilizing ground penetrating radar (GPR) on concrete slabs that consisted of simulated defects to mimic those found in real concrete structures. This served as a preliminary experiment to verify the GPR data with the design of the slabs. The following study describes a field investigation on an old bridge deck, which involved multiple testing methods. The techniques used were GPR, impact echo (IE), ultrasonic pulse echo …

Simple Rebar Anchorage Slip Macromodel Considering Corrosion, Ahmad Soraghi, Qindan Huang

Civil and Environmental Engineering Faculty Research and Publications

Reinforcement slip in the footing of a reinforced concrete (RC) column can significantly influence the lateral displacement of the column, a critical structural response under lateral loads such as seismic loading. Many past researchers studied and developed models to capture the anchorage slip of rebar; however, there is still a need for a model that can reflect the actual bond-slip relationship (especially in the presence of corrosion) and yet is simple-to-use for structural analysis. In this study, a simple bar stress-slip macromodel is developed to predict reinforcement anchorage slip given a rebar stress. The proposed rebar anchorage slip model is …

Quantitative Non-Destructive Evaluation Of Rebar Corrosion In Concrete, Khadiza Binte Jalal

Civil Engineering Dissertations

ABSTRACT: Corrosion of rebar is considered the leading cause of deterioration in concrete structures. When steel rust, it occupies larger volume and creates pressure on the concrete, leading to cracking and spalling. As the cross-section is being compromised, the structural capacity of the reinforced concrete structure is reduced. Corrosion is a slow natural electrochemical process that affects the long-term performance. However, sometimes premature catastrophic failure occurs due to corrosion, especially in chloride environments. Moreover, the cost of repair and replacement of deteriorated structures has become a major liability for management agencies. Consequently, it is important to determine the level of …

Machine Learning Based Prediction Of Reinforced Concrete Members’ Shear Friction Capacity, Farah Mohamed

Electronic Theses and Dissertations

Shear friction theory describes the mechanisms by which shear forces are transferred across concrete-to-concrete interfaces. Shear transfer across a plane involves a complex interaction of several phenomena, such as concrete surface condition and cohesion, concrete strength, and steel reinforcement strength and reinforcement ratio. Existing empirical equations for shear friction have been developed using limited sample data sets;thus, their accuracy is limited to the range covered by the data. In order to overcome this limitation, the present thesis proposes two machine learning models drawn from an extensive database to predict the shear friction capacity in reinforced concrete (RC) with a high …

Probabilistic Prediction Model For Rc Bond Failure Mode, Ahmad Soraghi, Qindan Huang

Civil and Environmental Engineering Faculty Research and Publications

Adequate rebar-concrete bonding is crucial to ensure the reliable performance of reinforced concrete (RC) structures. Many factors such as the concrete properties, concrete cover depth, transverse reinforcement, and the presence of corrosion will affect the bond behavior, and consequently, the structural performance. While many prior studies have focused on the influence of the aforementioned factors on the bond strength, the impact of these factors on the bond failure mode has not been thoroughly investigated. A probabilistic bond failure mode prediction model that considers various influencing factors including loading type and corrosion is developed in this study. This study uses the …

Use Of Carbon Fiber Reinforced Polymer (Cfrp) Including Sheets, Rods, And Ropes In Strengthening And Repairing Long Reinforced Concrete Columns, Yasir Matloob Saeed

Dissertations and Theses

The use of FRP materials in strengthening and repairing of reinforced concrete (RC) structures has increased in the past two decades. Recently, FRP materials have become one of the most used materials in rehabilitation engineering. For seismic retrofitting of RC structures, usually the process involves strengthening or repairing the vertical support elements of the buildings or bridges. Several studies focused on the use of FRP materials in strengthening and repairing RC columns. Externally bonded (EB) FRP sheets or laminates and near-surface-mounted (NSM) FRP rods have been used for enhancing the strength and ductility of RC columns. Although glass FRP (GFRP) …

Damage Observed In Structures Of Different Types During The Inspection After The Durrës Earthquake Of 26.11.2019 And Proposals For Their Repair, Arsim Rapuca, Naim Mushi

UBT International Conference

During the inspection of various construction structures such as: school buildings, houses, multi-storey buildings, etc. of different structural systems after the Durrës earthquake of 26.11.2019, various damages were observed in structural and non-structural elements. Damages were of various natures such as: defects during the implementation of structures, defects in the quality of materials, construction of additional floors on existing ones, use of structures with poor ductility such as massive masonry systems, negligence of supervision or construction without supervision, etc. In reinforced concrete structures, damage to the ground floor columns (mainly in plastic hinge regions), damage to the protective layers of …

Micro-Mechanical Analysis Of Corrosion Products Formed During Long-Term Carbonation Induced Corrosion Of Steel, Marijana Serdar, Dubravka Bjegovic, Valérie L’Hostis, Stéphane Poyet, Damien Féron

International Conference on Durability of Concrete Structures

During corrosion distinct types of corrosion products form, composed of different ratios of ferrous ions and oxide, hydroxides. Corrosion products have different physical and mechanical properties, mainly density, resistivity, volume and modulus of elasticity compared to iron. Knowing properties of corrosion products is indispensable for service life modelling of structures and can give valuable insight into the long-term corrosion propagation process. In this study micro-indentation method was used to evaluate mechanical properties of different layers formed during long-term carbonation induced corrosion of steel in concrete. Investigation was performed on three sets of reinforced concrete samples, that underwent corrosion during 50, …

Fem Analysis Of Structural Behaviour Of Reinforced Concrete Beam Under The Effect Of Frost Damage, Zhao Wang, Tamon Ueda, Hiroshi Hayashida, Dawei Zhang

International Conference on Durability of Concrete Structures

Minimizing frost damage is one of the important durability issues for concrete structures in cold and wet areas. This paper performed a Finite Element Model (FEM) analysis on the structural behavior of reinforced concrete beam under the effect of frost damage. The frost damage was considered as degradations in two constituents: concrete material and bond between concrete and reinforcement. The constitutive models of deteriorated concrete material were proposed using a mesoscale simulation approach (Rigid Body Spring Model). DIANA FEA program was adopted for the structural analysis and experiments were also conducted for the verification. It was clarified that the structural …

Performance-Based Economical Seismic Design Of Multistory Reinforced Concrete Frame Buildings And Reliability Assessment, Chunyu Zhang

UNLV Theses, Dissertations, Professional Papers, and Capstones

As the next generation of seismic design methodology, performance-based seismic design (PBSD) method requires a structure satisfy multiple preselected performance levels under different hazard levels. Optimal PBSD methods provide different strategies to design the numerous variables, including strength, stiffness and ductility of each structural component. The overall goal of this study is to develop a new optimal PBSD method for multi-story RC moment frames. This method is capable of overcoming the deficiencies of existing optimal PBSD methods and can be implemented by the U.S. design practice. The proposed method minimizes construction cost and takes the limit of member plastic rotation …

Behavior And Strength Of Rc Spandrel Members Under Unsymmetrical Bending And Torsion Including Cfrp Retrofitting, Muhammad Fahim

Civil & Environmental Engineering Theses & Dissertations

This dissertation presents the outcome of an experimental and theoretical investigation of the behavior and strength of reinforced concrete spandrel members both with and without carbon fiber reinforced polymer (CFRP) retrofitting. Both isolated spandrel members with L-shaped cross section as well as those integrated with reinforced concrete slabs are studied. A series of isolated spandrel members were tested under separate and combined actions of unsymmetrical bending and torsion. Six of these specimens were retrofitted externally with high-strength CFRP strips. Materially nonlinear analysis procedures are also formulated and programmed for the spandrel members with and without CFRP retrofitting. Furthermore, ultimate bending-torsion …

Dynamic And Static Behavior Of Hollow-Core Frp-Concrete-Steel And Reinforced Concrete Bridge Columns Under Vehicle Collision, Omar I. Abdelkarim, Mohamed Elgawady

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This paper presents the difference in behavior between hollow-core fiber reinforced polymer-concrete-steel (HC-FCS) columns and conventional reinforced concrete (RC) columns under vehicle collision in terms of dynamic and static forces. The HC-FCS column consisted of an outer FRP tube, an inner steel tube, and a concrete shell sandwiched between the two tubes. The steel tube was hollow inside and embedded into the concrete footing with a length of 1.5 times the tube diameter while the FRP tube stopped at the top of footing. The RC column had a solid cross-section. The study was conducted through extensive finite element impact analyses …

Behavior Of Fire-Exposed Rc Frames Before And After Jacketing, M. Monir M. Ajan Alhadid

Electronic Thesis and Dissertation Repository

Analysis and design of fire-exposed Reinforced Concrete (RC) frames before and after jacketing with concrete layers are commonly performed using prescriptive methods that rely on the concept of fire rating. These methods were developed based on empirical results on individual RC members subjected to certain fire conditions. In typical fire scenarios, the residual capacity, stiffness and thermal deformations affects not only the local performance of each fire-exposed member, but also the load redistribution and global behavior of the entire frame. In terms of fire safety, the philosophy of the new building codes considers objective-based design as an alternative of the …

Strength Of Reinforced Concrete Beams With High-Strength Steel, Brian C. Rogers, Aishwarya Puranam, Santiago Pujol

The Summer Undergraduate Research Fellowship (SURF) Symposium

Structures are commonly made of reinforced concrete, which is a composite material made of concrete and steel reinforcement. Using high-strength steel, with yield stress larger than 100 ksi, could help reduce the quantity of steel required in structural members, thus reducing costs and improving constructability. The hypothesis being tested is that smaller quantities of high-strength steel reinforcement (HSSR) can be used in place of conventional steel in reinforced concrete beams while maintaining similar strength and deformation at failure. Two reinforced concrete beams with two different types of longitudinal steel reinforcement were constructed. The beams were 18 in. wide, 30 in. …

High Strength Steel In The Reinforced Concrete Structures: Serviceability, Alan Kanybek, Aishwarya Puranam, Santiago Pujol

The Summer Undergraduate Research Fellowship (SURF) Symposium

The use of high-strength steel (yield stress larger than 100 ksi) in reinforced concrete structures can provide an effective alternative to using conventional steel (yield stress up to 80 ksi). The goal of this study is to investigate if slabs with reduced quantities of high-strength steel reinforcement meet the serviceability criteria. Instantaneous and long-term deflections in slab specimens with conventional steel and reduced amounts of high-strength steel (as compared with conventional steel) were studied. Two sets of two reinforced concrete slabs, each 14 ft. long, 30 in. wide, were built. The depth, quantity, and type of longitudinal reinforcement were varied …

Response Of High-Strength Steel Reinforced Concrete Structures To Simulated Earthquakes, Lucas Laughery

Open Access Dissertations

In reinforced concrete (RC) structures expected to resist earthquake demands, substituting smaller amounts of high-strength steel for conventional steel reinforcement can help reduce reinforcement congestion and placement costs while keeping strength unchanged.

Provided cross-sectional dimensions remain unchanged, reducing the amount of longitudinal steel in a member will result in a member with similar initial stiffness but lower post-cracking stiffness. Nominal strength can be kept nearly the same if this reduction in the amount of steel is accompanied by a corresponding increase in the strength of the steel. The topic of this investigation is whether two frames with the same initial …

Investigation Of A Novel 3d Non-Destructive Evaluation For Corrosion Process In Reinforced Concrete, Guohao Fang, Biqin Dong, Ningxu Han, Feng Xing

International Conference on Durability of Concrete Structures

X-ray computed microtomography (X-ray μCT) method is proposed to trace the corrosion features of steel bar in cementitious materials. Three-dimensional corrosion morphology (including morphology of steel corrosion, corrosion products and cracks formation) are characterized and reconstructed. Experimental results demonstrate that X-ray μCT can track time-dependent development of corrosion products and the subsequent initiation and propagation of corrosion-induced cracks. In addition, scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) are used to morphologically and chemically analyze the corrosion result. The microscopic analysis result is found to be in a very good agreement with the image analysis measured by X-ray μCT. …

An Experimental Study On Effect Of Steel Corrosion On The Bond–Slip Performance Of Reinforced Concrete, Xiaolin Zhang, Xuebing Liang, Hancheng Huang, Haijun Zhou

International Conference on Durability of Concrete Structures

This paper studied the effects of reinforcement corrosion on bond performance between rebar and concrete. Tests were carried out to evaluate the degradation of bond between reinforcing steel and concrete for different corrosion levels of reinforcing steel. A series of 20 specimens of different concrete strength with various reinforcing steel corrosion levels were designed and manufactured. Each specimen was casted as a 200-mm concrete cube, and a steel rebar was centrally embedded with two stirrups around it. The steel rebar were corroded using an electrochemical accelerated corrosion technique. The corrosion crack opening width and length were recorded after the corrosion …

Durability-Based Optimal Design Methodology For Rc Members In Corrosive Environment, Saeid A. Alghamdi, Shamsad Ahmad, Adamu Lawan

International Conference on Durability of Concrete Structures

No abstract provided.

Research On Concrete Durability Improving For Existing Island-Building And Its Application, Mao Jianghong, Zhu Yaofeng, Xu Fangyuan, Jin Weiliang, Xu Yidong, Chen Xu

International Conference on Durability of Concrete Structures

China’s coastal cities contain a large number of islands with abundant human activities, in which buildings are in a typical marine corrosion environment and the corrosion of reinforced concrete structures is very prominent. This paper makes research work on two aspects: (1) the durability assessment and durability improvement after a thorough investigation of the architecture of Xiangtan County, Ningbo city, on an island and (2) the application research of the bidirectional electromigration rehabilitation (BIEM) technology to enhance the durability of existing island building life. This paper designs a set of BIEM equipment based on solar power supply and develops a …

Effects Of Vertical Ground Motion On Seismic Performance Of Reinforced Concrete Flat-Plate Buildings, Sara Jean George

UNLV Theses, Dissertations, Professional Papers, and Capstones

Reinforced concrete flat plate is a type of structural system widely used for office and residential buildings in many areas including those with high seismic risk. In the regions of high seismicity, moment frames or shear walls are employed to resist lateral loading while the flat-plate system is designed to primarily resist gravity loading. Flat-plate structures must maintain lateral deformation capacity as well as resist gravity loading under seismic loads. The deformation capacity of a slab-column connection is a function of vertical shear transferred from slab to column. The effects of vertical loading become even more exaggerated when the flat-plate …

Circular Rc Columns Partially Confined With Frp, Sahar Y. Ghanem

Theses and Dissertations--Civil Engineering

Wrapping reinforced concrete (RC) columns with Fiber Reinforced Polymer (FRP) composites is effective in increasing their capacity. The current state of art concentrates primarily on fully wrapped RC columns and few studies dealt with partially wrapped columns. The majority of the studies did not account for the influence of the existing steel reinforcement on the column’s behavior. Other studies estimated the total confinement pressure as the sum of the confinement pressure due to the external FRP jacketing and due to the internal transverse steel reinforcement. Few models dealt with the coupled effect of the confinement from steel and partial FRP …

Shear Behavior Of Reinforced Fly Ash-Based Geopolymer Concrete, Noor S. Yacob

Masters Theses

"The geopolymerisation of aluminosilicate materials such as fly ash has been a radical change in construction material's chemistry and composition, compared to the portland cement-based concrete calcium silicate-hydrate chemistry. The adoption of fly ash in concrete industry is a good use of by-product ashes to reduce emissions of the greenhouse gas implicitly. However, in this research, the replacement of portland cement by fly ash is 100%, which makes it a zero-cement concrete with no proprietary chemical additives.

Geopolymer concrete (GC) is a revolutionary synthetic material that combines sustainability and high engineering properties, and it is relatively cost-effective compared to portland …

Seismic In-Plane Response Of Reinforced Concrete Frames With Masonry Infill Walls, Rabab Abdel Karim Al Louzi

Open Access Dissertations

Field data gathered after destructive earthquakes indicate that infill walls interact with reinforced concrete (RC) frames in buildings during an earthquake and could cause failure mechanism different than what the frames are originally designed for. A new method to identify the failure modes of RC frames with infill walls is developed. The method requires only the simple geometric and material properties of the elements involved in the frame- wall assembly. The approach checks various possible failure mechanisms, including those that may evolve depending on how the infill wall may fail during strong shaking, for example, the dynamically evolved captive column …

Evaluation Of Collapse Indicators For Seismically Vulnerable Reinforced Concrete Buildings, Nicholas R. Skok

Open Access Theses

Older reinforced concrete buildings can be prone to column shear and compression failures during earthquakes because of inadequate transverse reinforcement. Cities in seismic areas still have large inventories of older and potentially deficient buildings. To analyze every building and estimate its vulnerability in detail is costly. A simple method to rank quickly older buildings according to their seismic vulnerability is needed to help engineers prioritize the use of resources for rehabilitating the most vulnerable buildings.

Four indicators of building damage or collapse were evaluated using numerical analysis and prior data from building surveys: column index (Hassan & Sozen, 1997), R …

Progressive Collapse Analysis Of Older Reinforced Concrete Flat Plate Buildings Using Macro Model, Jinrong Liu

UNLV Theses, Dissertations, Professional Papers, and Capstones

Catastrophic progressive collapse of a building can be triggered by a sudden loss of a load-bearing element in an abnormal loading event. There is a large inventory of reinforced concrete flat plate buildings designed in accordance with older codes. Without using shear and integrity reinforcement in slabs, these older flat plates are vulnerable to progressive collapse. The overall goal of this research is to numerically examine the resilience of older flat plate buildings against progressive collapse due to instantaneous removal of an exterior or interior column.

To achieve the research goal, a macro behavioral model of slab-column frame is created …

Shear Capacity Of Reinforced Concrete Beams At Elevated Temperatures, Mohamed Diab

Electronic Thesis and Dissertation Repository

Fire safety is an important design aspect that ensures structural integrity of a Reinforced Concrete (RC) building during fire events. As new codes are moving from prescriptive methods to performance-based methods, design engineers are in need of rational design tools to assess the capacity of RC elements during a fire event. Previous research work focused on the flexural and axial capacities of concrete elements exposed to fire. Research addressing the shear capacity of concrete elements exposed to fire is limited in the literature.

An analytical method to predict the shear capacity of RC beams exposed to elevated temperatures is proposed. …

Ultrasonic Pulse Velocity Investigation Of Steel Fiber Reinforced Self-Compacted Concrete, Belayhun Tesfaye Gebretsadik

UNLV Theses, Dissertations, Professional Papers, and Capstones

Concrete is a basic material used for a number of applications in civil engineering projects. Structural concrete is brittle material under normal conditions. Therefore, by adding short and randomly distributed steel fibers, it is possible to improve the ductility and other basic properties of concrete. However, the addition of steel fibers results in loss of workability of the concrete, especially in self-compacted concrete. Therefore, in this study, ADVA-140 high range water reducer (HRWR) superplasticizer was added to improve the workability of self-compacted (SC), steel-fiber-reinforced concrete (SFRC). The amount of superplasticizer varied with the volume percentage of fiber for the beams; …

Mitigation Of Chloride And Sulfate Based Corrosion In Reinforced Concrete Via Electrokinetic Nanoparticle Treatment, Kunal Kupwade-Patil

Doctoral Dissertations

Concrete is a porous material which is susceptible to the migration of highly deleterious species such as chlorides and sulfates. Various external sources, including sea salt spray, direct seawater wetting, deicing salts and chlorides can contaminate reinforced concrete. Chlorides diffuse into the capillary pores of concrete and come into contact with the reinforcement. When chloride concentration at the reinforcement exceeds a threshold level it breaks down the passive oxide layer, leading to chloride induced corrosion. The application of electrokinetics using positively charged nanoparticles for corrosion protection in reinforced concrete structures is an emerging technology. This technique involves the principle of …