Osman Ozbulut

University of Virginia | UVa · Department of Civil and Environmental Engineering (CEE)

This study presents a life-cycle-assessment-based investigation of the environmental impacts of recycled plastic modified (RPM) asphalt mixtures compared with conventional unmodified and polymer-modified mixtures in Virginia, U.S. The types of recycled plastic used as a modifier via the dry process were polyethylene terephthalate and a combination...

On February 6, 2023, at 04:17 and 13:24 local time, two major earthquakes struck Pazarcık and Elbistan districts of Kahramanmaraş, Turkey. The first earthquake had a moment magnitude of the Mw = 7.7 at a depth of 8.6 km, while the second earthquake had a magnitude of the Mw = 7.6 at a depth of 7 km. The earthquakes impacted eleven cities in Turkey,...

Superelastic shape memory alloy (SMA) cables have been considered in the development of various seismic protection technologies. The cyclic nature of seismic loads necessitates a comprehensive understanding of the mechanical behavior of SMA cables under repeated loading conditions. As SMAs undergo repeated phase transformation cycles, alterations i...

This paper introduces a novel hybrid damper called the Superelastic Friction Damper (SFD) and evaluates its performance through nonlinear time history analyses. The SFD combines the high tensile resistance and excellent self-centering capability of shape memory alloy (SMA) cables with the non-sacrificial energy dissipation provided by a frictional...

This study explores comparative seismic performance of a shape memory alloy (SMA)-only device, a hybrid self-centering device, and a friction damper. SMA-based hybrid device considered in this study, named as superelastic friction dampers (SFDs), has been recently proposed and experimentally characterized. A brief description of the device and its...

This study explores comparative seismic performance of a shape memory alloy (SMA)-only device, a friction damper, and a hybrid self-centering device. The self-centering device considered in this study, named as superelastic friction dampers (SFDs), is a hybrid damper operating on a mechanism where SMA cables and frictional components are arranged i...

This study proposes a new self-centering, shape memory alloy bar-based device to address the tension-compression asymmetry and limited energy dissipation capacity of similar SMA bar-based devices. The proposed device, named the Confined Superelastic Friction Damper (CSFD), employs buckling-restrained SMA bars to maintain symmetry in force-displacem...

This study presents a finite element model for a hybrid self-centering damper considering the rate and temperature effects and explores the effects of different design parameters on the damper response. The damper, called as superelastic friction damper (SFD), consists of superelastic shape memory alloy (SMA) cables and a frictional energy dissipat...

This paper investigates the seismic performance enhancement of steel frame buildings using a novel hybrid self-centering braces (HSBs) under extremely rare earthquake events. The hybrid self-centering brace consists of shape memory alloy (SMA) cables and viscoelastic (VE) dampers. A prototype bracing system is designed and fabricated to explore its...

The objective of this study was to explore the use of monotonic loading tests (''monotonic tests'') as screening tools to assess the rutting potential of dense-graded asphalt surface mixtures in Virginia. To that end, three monotonic tests-the indirect tensile at high temperature (IDT-HT) test, the rapid rutting (RR) test, and the Marshall stabilit...

This study discusses the development and experimental characterization of a new seismic damper that can provide stable energy dissipation with high self-centering capabilities. The proposed system, called as superelastic friction damper (SFD), leverages advantages offered by superelastic shape memory alloy (SMA) cables to create a full-scale seismi...

Graphene and its derivatives have been studied as nano-reinforcement in cement-based composites to improve their mechanical, transport and durability characteristics. However, the agglomeration effect due to the strong van der Waals force between graphene sheets makes the uniform dispersion difficult and limit the efficacy of graphene. The goal of...

The Virginia Department of Transportation (VDOT) is currently using the asphalt pavement analyzer (APA) as a testing tool to screen the rutting potential of asphalt mixtures as part of its balanced mix design (BMD) method. However, the cost and availability of APA equipment in VDOT and contractor laboratories and the speed of testing are main barri...

This study explores the development of a shape memory alloy (SMA)‐based hybrid self‐centering brace that combines NiTi superelastic cables with viscoelastic dampers. First, the behavior of individual components of the hybrid self‐centering brace, that is, SMA cables and viscoelastic damper is characterized under various experimental conditions. The...

Graphene nanoplatelets (GNPs) that possess high electrical conductivity and relatively low cost have been considered to obtain self-sensing capability in cementitious composites. However, there is limited understanding on the effects of physical properties of GNPs such as particle size and surface area on the self-sensing characteristics of the cem...

A new hybrid shape memory alloy (SMA)-based damper was developed to address two major challenges for SMA-based seismic control devices: (i) insufficient force capacity for real-world application and (ii) relatively low energy dissipation capacity. The hybrid damper, named Superelastic Friction Damper (SFD), leverages the high tensile resistance and...

While the multi-level SMA/lead rubber bearing isolation system (ML-SLRB) has been proposed and numerically studied, its application remains a challenge in the absence of experimental validation. In this paper, experimental test of a multi-level SMA/lead rubber bearing isolator(ML-SLRB) was conducted and mechanical responses of the isolator were stu...

This paper proposes an adaptive friction isolation system (AFIS) composed of shape memory alloy (SMA) cables and double friction pendulum bearings (FPBs). Double FPBs with different friction coefficients enable two-level response characteristics that are advantageous at frequent and design basis hazard levels, while SMA cables with initial slack pr...

The applications of carbon fiber reinforced polymers (CFRPs) to strengthen aging steel structures and bridges have recently gained a wide interest due to their ease of use, corrosion resistance, and high tensile strength. In this research, the effects of aggressive corrosion environment on the mechanical and fatigue properties of CFRP strand sheet/...

In traditional strategies for structural health monitoring of concrete structures, distributed sensors are commonly utilized to monitor and evaluate the state of the structure. This requires deployment of a large number of sensors to obtain sufficient information that can help the owners and engineers to timely detect anomalies in the structural pe...

Balanced mix design (BMD) is gaining popularity among highway agencies in the United States. That is because such concept allows innovations to be responsibly incorporated into asphalt mixtures, and quantifies the quality, where the volumetric properties and gradations alone cannot differentiate asphalt mixture performance. Additionally , such conc...

This study investigates the seismic performance of multiple reinforcement, high-strength concrete (MRHSC) columns that are characterized by multiple transverse and longitudinal reinforcements in core areas. Eight MRHSC columns were designed and subjected to a low cycle, reversed loading test. The response, including the failure modes, hysteretic be...

In this paper, the effects of ambient temperature on the tensile response and superelastic fatigue behavior of the shape memory alloy (SMA) cable are investigated. The tested SMA cable is made of Nickel–Titanium and has an outer diameter of 8 mm with a 7 × 7 configuration. The SMA cables are subjected to an incrementally increasing loading protocol...

This study investigates the response of a shape memory alloy (SMA)-based isolation system that combines multiple groups of SMA cables and a lead rubber bearing. The isolation device, named as multi-level SMA/lead rubber bearing (ML-SLRB), is designed such that it maintains its efficiency under frequent, design and extreme levels of seismic events....

Multifunctional self-sensing smart concrete can provide a structural health monitoring (SHM) solution that is robust, reliable, and low-cost. Smart concrete, which includes coarse aggregates with 15 mm size, brass fibers, silica fume, superplasticizer and water, has been developed as a promising multifunctional material. The normal and cross compre...

Shape memory alloy (SMA)-based seismic isolation systems can successfully reduce the peak and residual displacements of bridges during strong earthquake, but they commonly lead to an increased force demands in substructure. This study explores the development of an SMA cable-based negative stiffness isolator to alleviate this problem. The proposed...

Description As the field of additive construction continues to grow exponentially, new standards will be needed for this expanding technology to ensure the safety of the public. Sponsored by ASTM International Committee C09 on Concrete and Concrete Aggregates, this book provides the provides the latest qualification procedures being proposed by res...

In this paper, an experimental investigation is carried out to study the effects of graphene nanoplatelets (GNPs) on the mechanical properties of cementitious composites with coarse aggregates. The concrete mixtures with GNPs concentrations ranging from 0.025% to 0.10% by weight of the cement are prepared, where a wet dispersion technique that empl...

This study explores the experimental response and failure behavior of an SMA cable brace. The kernel of the developed SMA brace consists of four SMA cables with a diameter of 8 mm. The cables are configured within bracing system in a way that they are only subjected to tensile loads regardless of the loading direction of the bracing itself. A mecha...

In this paper, a new shape memory alloy (SMA) damping device named confined superelastic dissipator (CSD) was examined. The proposed dissipator consists of a fused superelastic nickel‐titanium (NiTi) SMA bar as the functional kernel component encased in grout‐filled steel tube. The bar carries the axial load and dissipates energy through axial defo...

In this paper, two types of mechanical anchorage systems for shape memory alloy (SMA) cables are developed and their performance and feasibility are experimentally evaluated under various loading conditions. First, the detailed descriptions of two anchorage systems and the installation of SMA cables into the anchorage systems are described. Then, t...

This article explores the tensile deformation and failure characteristics of a hybrid composite where microscale shape memory alloy (SMA) fibers and nanoscale graphene nanoplatelets (GNPs) were used to reinforce a ductile epoxy matrix. First, the GNPs were incorporated into epoxy system using a hybrid dispersion technique at various weight percenta...

Self-sensing smart cementitious materials can enable development of load carrying structural systems with an intrinsic condition monitoring system. This paper discusses extensive experimental tests conducted on the brass fiber reinforced concrete composites that incorporates coarse aggregates. First, compressive and split tensile tests were conduct...

Superelastic shape memory alloys with ultra-high-strength, large mechanical hysteresis, and the ability to recover large deformations are promising materials for damping applications. In this study, the superelastic response and damping capacity of quaternary Ni45·3Ti39.7Hf10Pd5 polycrystalline alloys are investigated in compression in terms of tem...

Superelastic shape memory alloys are a unique class of smart materials that can recover up to 6% strains. Due to their appealing properties such as high energy dissipation and corrosion resistance, several researchers have assessed the use of such materials in numerous applications ranging from biomedical to civil engineering. This article investig...

To prevent unseating failures and pounding problems in simply supported bridges, steel restrainers that can limit relative displacements of adjacent spans have commonly been used. This study proposes a shape memory alloy (SMA)-based restrainer that can serve as both energy dissipater and restrainer under cyclic tension and compression loading. The...

This study characterizes tensile behavior of graphene nanoplatelets (GNPs) reinforced cementitious composites using acoustic emissions (AE). Two acoustic sensors were attached to dog-bone specimens that were cast using GNP nano-reinforced mortar composites at concentration levels of 0% to 0.5% by weight of cement. The specimens were tested under di...

This study explores the flexural behavior of reinforced concrete (RC) columns strengthened with near surface mounted (NSM) shape memory alloy (SMA) bars or carbon fiber reinforced polymer (CFRP) bars. Seven RC column specimens were designed and fabricated to study the influence of different variables on the flexural response of the strengthened col...

This study presents a methodology to generate probabilistic seismic demand models and hazard curves for steel frames with or without shape memory alloy (SMA) bracing systems under mainshock – aftershock sequences. First, three post-mainshock damage states were defined based on both peak inter-story drift and residual drift ratios. Incremental dynam...

This paper examines the buckling and post-buckling behavior of superelastic shape memory alloy (SMA) bars. A NiTi SMA bar with a diameter of 12 mm was used in all the experimental tests. First, the tensile and compression responses of NiTi bar were characterized under monotonic loading up to failure. A total of 15 specimens with slenderness ratios...

Aluminum alloys (AAs) possess various advantageous properties such as good corrosion resistance and high ductility and have recently gained interest in strengthening reinforced concrete (RC) structures. This paper investigates the potential application of AA bars as the near‐surface mounted (NSM) reinforcement in flexure strengthening of RC beams....

Self-sensing cementitious composites can enable structures that are capable of carrying the loads applied on them while monitoring their condition. Most of earlier research has focused on the incorporation of nanofillers or microfibers into cement paste or mortar composites. However, there have been very limited number of studies on the development...

This paper investigates the seismic and collapse performance of shape memory alloy (SMA) braced steel frame structures considering the effects of various brace design parameters and ultimate state of SMAs. An SMA‐braced steel frame building is designed to have comparable strength and stiffness with a steel‐moment resisting frame selected as case st...

Shape memory alloys (SMAs) are a class of metallic alloys that possess remarkable characteristics such as superelasticity and shape memory effect. Superelastic SMAs have been considered as fiber in polymer composites due to their ability to recover their deformation upon removal of load, good energy dissipation capacity and impact resistance. Graph...

Over the past decade, shape memory alloy (SMA) in the form of wires and cables have been extensively studied for various structural engineering applications. There are numerous application areas where pure compression (or coupled with tension) is the primary load bearing scenario, which requires larger size SMA bars. However, the compression behavi...

Over the past decades, a number of structural health monitoring methods have been developed for condition assessment of concrete structures. Most of these methods require the installation of external sensors. Accelerometers are commonly used for vibration-based damage detection for the entire structure, while strain gauges are installed in order to...

This study investigates the mechanical properties of ASTM A1010 steel plates and assesses their cost efficiency through life cycle cost (LCC) analyses when used in bridge construction. First, tensile tests were conducted on specimens with different plate thicknesses and rolling direction orientations. The overall stress-strain response and tensile...

This study investigates the tensile behavior of ductile and brittle epoxy polymers reinforced by graphene nanoplatelets (GNPs) dispersed by various methodologies. Dispersion of GNPs into the epoxy matrix using sonication or sonication in combination with high shear mixing was investigated. Also, the effectiveness of the dispersion of GNPs into epox...

This article presents a non-destructive approach for load rating of reinforced concrete bridges without structural plans. The approach is found on a hybrid method, which employs vibration and live load testing coupled with numerical simulation and model updating techniques, to converge on estimate of unknown structural parameters. The material prop...

This study explores seismic performance of steel frame buildings with SMA-based self-centering bracing systems using a probabilistic approach. The self-centering bracing system described in this study relies on superelastic response of large-diameter cables. The bracing systems is designed such that the SMA cables are always stressed in tension. A...

Graphene nanoplatelets (GNPs) have the same chemical structures as carbon nanotubes but their internal structure consists of multiple layers of graphene with thicknesses of only a few nanometers. Compared to carbon nanotubes, GNPs are less prone to agglomeration and entanglement when they are used as nanofillers in composite materials. This paper i...

FULL TEXT AVAILABLE ON REQUEST Superelastic shape memory alloys (SMAs) are smart materials that can recover 6–8% elastic strains due to their phase transformation. SMAs also possess unique characteristics such as good energy dissipation, excellent re-centering capabilities and corrosion resistance. Recent studies have incorporated the use of super...

Load rating describes the processing of quantifying the safe live load carrying capacity of an existing bridge. For most bridges, this load rating is derived as an analytical solution based on the structural design details and operational condition state. However, for structures without plans or insufficient structural details available it is diffi...

Superelastic viscous damper is a passive hybrid control device that combines shape memory alloy cables and a viscoelastic damper to mitigate dynamic response of structures subjected to multi-level seismic hazards. In the hybrid device, shape memory alloy cables that exhibit a nonlinear but elastic response are used mainly as re-centering unit, whil...

Graphene nanoplatelets (GNPs) have the same chemical structures as carbon nanotubes but their internal structure consists of multiple layers of graphene with thicknesses of only a few nanometers. Due to their increased thickness, GNPs are less prone to agglomeration and entanglement when they are used as nanofillers in composite materials. Although...

This study explores the aftershock collapse performance of steel buildings designed with superelastic viscous dampers (SVDs) under seismic sequences. The SVD strategically combines shape memory alloy (SMA) cables and a viscoelastic compound to provide good self-centering and damping capabilities. A nine-story steel special moment resisting frame (S...

This paper presents a method for identifying the flexural rigidity of bridges with limited structural information using modal frequencies identified from measured acceleration data. The output of this study provides a simple approach that can be adapted for condition assessment, the bridge load rating process, and nondestructive evaluation. The ove...

People use infrastructure systems mostly without realizing how important these systems are until an attack or damage occurs and results in casualties or causes discomfort or inconvenience. Even though there have been numerous studies on critical infrastructure protection in the literature, there has not been any published document on a simplified a...

There are several different mechanisms for creating a restoring force to return a building structure to plumb after an earthquake. One approach is to allow structure to undergo controlled rocking at discrete locations such as column-base joint or beam-column joints. Another approach is to employ braces or seismic control devices with self-centering...

Conventional earthquake resisting structural systems are deemed to provide adequate safety without significant damage for design level earthquake intensities. However, these systems significantly depend on inelastic deformations to resist strong ground shakings. Thus, high repair costs and associated business downtime are inevitable. This paper int...

The microstructure and shape memory properties of Ni40.3Ti39.7Hf15Pd5 and Ni40.3Ti44.7Hf10Pd5 alloys were investigated. It was revealed that transformation temperatures of these alloys can be tailored by thermal treatments and composition alteration. Heat treated Ni40.3Ti39.7Hf15Pd5 can show shape memory effect at above 100 °C. Both alloys showed s...

Current vibration based-structural health monitoring strategies have relied on vibration measurement methods using affixed accelerometers as a standard practice, but a fundamental limitation of this approach is that these sensors only provide point measurements. This low spatial resolution ultimately limits the effectiveness of structural monitorin...

This study explores the use of superelastic shape memory alloy (SMA) strands, which consist of seven individual small-diameter wires, in an epoxy matrix and characterizes the tensile and fatigue responses of the developed SMA/epoxy composites. Using a vacuum assisted hand lay-up technique, twelve SMA fiber reinforced polymer (FRP) specimens were fa...

Fiber reinforced polymer (FRP) composites have been extensively used for strengthening concrete structures. To manufacture FRPs or bond them to concrete structures, usually thermoset polymers are used. The mechanical properties and integrity of these adhesives significantly affect the performance of FRP-strengthened structures. Graphene nanoplatele...

Fiber-reinforced polymer (FRP) composites have been frequently used for strengthening concrete structures. However, conventional FRPs exhibit brittle behavior with relatively low ultimate tensile strains and limited energy dissipation capacity, and possess limited fatigue life. Superelastic shape memory alloys (SMAs) are a class of metallic alloys...

In this paper, a new structural identification method is proposed to identify the modal properties of engineering structures based on dynamic response decomposition using the variational mode decomposition (VMD). The VMD approach is a decomposition algorithm that has been developed as a means to overcome some of the drawbacks and limitations of the...

Although the use of near-surface mounted (NSM) fiber reinforced polymer (FRP) reinforcement satisfactorily enhances the flexural capacity of deficient reinforced concrete beams, the concrete beams strengthened with NSM FRPs typically exhibit brittle behavior. Aluminum alloy (AA) bars possess non-corrosive characteristics like FRPs but also exhibit...

This paper discusses the tensile response and functional fatigue characteristics of a NiTi shape memory alloy (SMA) cable with an outer diameter of 5.5 mm. The cable composed of multiple strands arranged as one inner core and two outer layers. The results of the tensile tests revealed that the SMA cable exhibits good superelastic behavior up to 10%...

The functionality of the U.S. transportation infrastructure system is dependent upon the health of an aging network of over 600,000 bridges, and agencies responsible for maintaining these bridges rely on the process of load rating to assess the adequacy of individual structures. This paper presents a new approach for safety screening and load-capac...

This study investigates the flexural behavior of reinforced concrete beams strengthened with near surface mounted (NSM) basalt fiber reinforced polymer (BFRP) bars. A total of five concrete beams with a length of 2100 mm were prepared with different internal longitudinal reinforcement and strengthening reinforcement ratios. Four-point bending tests...

This study explores the mechanical response of a high‐damping rubber damper (HRD) under different loading conditions. HRD is a typical viscoelastic damper that consists of 2 layers of elastomer compound sandwiched between 3 steel plates. The elastomer compound used in this study is a synthetic isoprene rubber reinforced with carbon black and design...

The addition of fibers to cementitious composites can provide improved ductility, energy dissipation, and resistance to cracking. However, it is also important to minimize residual deformations and provide crack-closing capabilities when the material is subjected to cyclic loading. In this study, the behavior of mortar mixtures with randomly distri...

Designing structures to withstand dynamic environmental hazards such as earthquakes, strong winds, and hurricanes is of primary concern for civil engineers. In addition, recent advances in architectural forms, structural systems, and high performance materials have enabled the design of very slender and lightweight structures. These flexible struct...

This paper presents a method for identifying structural stiffness of skewed reinforced concrete slab bridges with limited structural information using measured acceleration data. This information might be used for nondestructive evaluation, condition assessment, and load rating of bridges. A large number of slab bridges with different structural di...

FULL TEXT AVAILABLE ON REQUEST Superelastic shape memory alloys (SMAs) are metallic alloys that can recover their nonlinear deformations upon unloading. The use of SMAs in cementitious composites as fibers can enable crack recovery and re-centering capabilities. In this study, the crack recovery characteristics of SMA fiber reinforced mortar speci...

In highly corrosive and saline conditions, such as bridges near salt water or those exposed to deicing salt, conventional structural steels experience high corrosion rates, and weathering steels fail to develop their protective coating. In contrast to conventional structural steels which are prone to corrosion when exposed to the environment, stain...

The use of superelastic shape memory alloy (SMA) bars in the near-surface-mounted (NSM) strengthening application can offer advantages such as improved bond behavior, enhanced deformation capacity, and post-event functionality. This study investigates bond characteristics and load transfer mechanisms between NSM SMA reinforcement and concrete. A mo...

Superelastic shape memory alloys (SE SMAs) are smart materials that recover 6–8% of inelastic strains upon unloading and exhibit good energy dissipation. In this study, the mechanical behavior of cementitious composites, reinforced with steel and SE SMA fibers, under flexure was examined. Fiber reinforced concrete, with a total fiber volume ratio o...