Global awareness and preservation have spurred increasing interest in utilizing environmentally friendly materials for high-performance structural applications. Biocomposites pose an appealing solution to this issue and are characterized by their sustainable lifecycles, biodegradable qualities, light weight, remarkable strength, and exceptional stiffness. Many of these structural qualities are found in applications that exhibit flexural loading conditions, and this study focuses on improving the bending performance of engineered biocomposite structures. The current application of biocomposites is increasing rapidly, so this expanding research explores other natural constituent materials for biocomposite structures under flexural loading. The renewable material investigated in this study was experimentally and numerically validated by optimizing the mechanical characteristics of bamboo fibers in biocomposite structures under flexural loading conditions through various thermal and organic chemical treatment methods. Therefore, bending performance of a biocomposite truss and I-beam are analyzed to demonstrate the benefits of utilizing optimally treated bamboos in their design. To accomplish this goal, the first task consisted of treating bamboos by thermal and chemical means to determine the resulting effects on the compressive and tensile mechanical properties through experimental testing. Results indicated a significant improvement in strength, stiffness, and weight reduction. An extensive analysis determined the optimal treatment method that was utilized for flexural loading conditions. The second task entailed studying the flexural behavior of the optimally treated bamboo in two geometric configurations, a hollow cylinder and veneer strip, to determine the resultant properties for the truss and I-beam structure. The effect of node location on flexural performance was also studied to establish design guidelines for the applied structures. Bending tests indicated that node location affects the strength and stiffness of the hollow cylindrical configuration but has minimal effects on the veneer strip. Observations discovered by this study were employed into the designs of the applied structures that yielded excellent mechanical performance through flexural testing. The final task required conducting a finite element analysis in Abaqus/CAE on the performance of each structural application to validate experimental results. A conclusive analysis revealed good agreement between the numerical method and experimental result.

The demand for an insert on composite sandwich structures to aid in the arrestment of face-core delamination is of great need. This research studies the use of a damage arrestment device (DAD) that connects the carbon fiber face sheets to the foam core to find whether an increase in the structural integrity of the sandwich beam results. Experimental analysis was employed to test the samples and was verified by a theoretical and finite element approach. The mechanical properties of LTM45/CF1803 pre-impregnated carbon fiber and Last-A-foam FR 6710 polyvinylchloride foam were experimentally analyzed using ASTM D3039 and ASTM D1621 standards respectively to verify the manufacturer’s data for the given material. With all the mechanical data, the effects of adding DAD keys to a delaminated composite sandwich beam were studied under a four-point bending test using ASTM standard D6272 and compared with non-delaminated beams to see if an increase in ultimate strength could be achieved. The initial delamination in the beams under consideration was one inch in length and located in between the loaded span of the beam. Two control beams were utilized for comparison: one with no defects, and another with a one inch delamination introduced at the face-core interface. The DAD keys were added in two different configurations to potentially stop the delamination propagation and increase the ultimate strength. In the first configuration DAD keys were added 0.25 inches on either side of the initial delamination in the transverse direction and provided a significant increase in strength over the delaminated control beam. The second configuration had a DAD key running along the longitudinal axis of the sandwich beam and resulted in a significant increase in ultimate strength over the delaminated control beam. After testing ten successful samples for each of the six different configurations, it was concluded that the addition of DAD keys in both configurations significantly increased the structural integrity of both the delaminated and non-delaminated control beams. With all the experimental data acquired, finite element models were created in COSMOS. The purpose of the finite element analysis was to validate the experimental results by comparing the deflections of the beam subjected to four-point bending during the experiment to the deflections found numerically. The deflections for the various DAD key configurations found in the experimental work were in agreement with the finite element results.

High-strength steel (HSS) conforming to ASTM A1035 is becoming increasingly used in various structural applications, including in high-rise buildings and bridges. Due to their chemistry and manufacturing process, ASTM A1035 steel bars result in a combination of high tensile strength to yield ratio and varying levels of corrosion resistance. One potential application of ASTM A1035 bars is in the blast-resistant design of concrete structures, where their use can allow for reduced steel congestion, and increased blast resistance. Despite their high initial cost, stainless steel (SS) reinforcing bars are also seeing increased use in concrete construction. Solid stainless steel bars are referenced in ASTM A955, which is applicable to various stainless steel alloys. In addition to their inherent corrosion resistance, most stainless steel bars possess greater tensile strength, and importantly, exceptional ductility, when compared to ordinary steel reinforcement. This unique combination of strength and ductility makes SS bars well-suited for blast design applications. The overarching aim of this thesis is to gain better understanding of the blast behavior of RC flexural members designed with high-strength (HSS) and stainless steel (SS) reinforcement. This objective is achieved through a combined experimental and numerical research program. As part of the experimental research, a large set of beams, subdivided into three series, are tested under either quasi-static bending or simulated blast loads using the University of Ottawa shock-tube. Series 1 (HSC-HSS) and Series 2 (HSC-SS) aim at examining the effects of blast detailing (as recommended in modern blast codes,) on the quasi-static, blast and post-blast behaviour of high-strength concrete (HSC) beams reinforced with either ASTM A1035 high-strength bars (8 beams) or ASTM A955 stainless steel bars (16 beams). In addition to the influence of detailing, the effects of steel grade/type, steel ratio and steel fibers are also studied. Series 3 further studies the benefits of combining higher grade or higher ductility reinforcement, with more advanced ultra-high performance concrete (UHPC). This series includes 20 UHPC beams built with either ordinary, HSS or SS reinforcing bars (UHPC-NSS, UHPC-HSS and UHPC-SS). In addition to the effect of steel grade/type, concrete type, steel ratio and steel detailing are also studied. The results from Series 1 and 2 demonstrate the benefits of implementing high-strength and stainless steel reinforcement in HSC beams subjected to blast loads, where their use leads to increased blast capacity, reduced support rotations, and higher damage tolerance. The results further demonstrate the benefits of “blast detailing” on the ductility and resilience of such beams, under both static and blast loads. The results also show that the use of steel fibers can be used to relax blast detailing in the beams with high-strength or stainless steel by increasing the required tie spacing from d/4 to d/2. The results from Series 3 confirm that the use of UHPC in beams enhances flexural response (in terms of strength and stiffness), which in turn results in superior blast resistance. Conversely, the high bond capacity of UHPC makes such beams more vulnerable to bar fracture. Increasing the steel ratio is found to effectively increase the failure displacement and ductility of the UHPC beams. The use of high-strength steel is found to increase load capacity and blast resistance, while the use of stainless steel results in remarkable ductility, which further enhances beam response under blast loading. As part of the numerical research program, the static and blast responses of the test beams are simulated using either 2D or 3D finite element (FE) modelling, using software VecTor2 and LS-DYNA. The numerical results show that the 2D FE modelling using software VecTor2 can provide reliable predictions of the static and blast responses of the HSS or SS reinforced HSC beams built with varying detailing, in terms of load-deflection response, cracking patterns, failure mode, displacement time histories and dynamic reactions. Likewise, the 3D FE modelling using software LS-DYNA with appropriate modelling of UHPC (using the Winfrith Concrete or CSCM models) can well predict the blast responses of UHPC beams with ordinary, high-strength and stainless steel, in terms of displacement/load-time histories, damage and failure modes.

Composite beams are frequently used in building, combining a steel beam with either a concrete-filled steel deck or solid concrete slab. To ensure proper composite action, shear connectors, typically in the form of headed shear studs, are utilized. Traditionally, the strength assessment of these headed shear studs is made using empirical design specifications that are based on push-out tests, which have been widely conducted and standardized over the years. However, the standardized push-out tests have short-comings, such as uneven slab bearing, slab buckling, questions regarding the distribution of load to each stud, etc. A study was conducted to evaluate and compare the existing push-out test setup with two alternative test setups. The study also aimed to examine the behavior of headed shear studs in composite beams having deck deeper the current allowable limit of 3 in., as specified by American Institute of Steel Construction (AISC) design specification. While the standard specification allows for steel decks with rib heights of up to 3 in., there are deck profiles deeper than 3 in. available in the market. Utilizing these deeper decks in composite beams offers several advantages, including faster and more cost-effective construction by reducing the number of beams required. This research therefore found that a major challenge in creating an alternative test setup involves eliminating moment at the interface between the concrete-filled steel deck and the steel beam. This moment leads to tension in the headed shear stud/stud group closest to the actuator, thus affecting the shear strength of the headed shear studs. Further, these headed shear studs have significant strength when used with 3.5 in. decks but further research is necessary. / Master of Science / Composite beams are widely used in building construction, combining a steel beam with either a concrete-filled steel deck or a solid concrete slab. To ensure their proper function, shear connectors are used, typically in the form of headed shear studs. Traditionally, the strength of these shear studs is determined using standardized push-out tests, but these tests some challenges like uneven slab bearing, questions about even load distribution, etc. In this study, the existing push-out test setup was evaluated and compared with two alternative setups. The behavior of headed shear studs in composite beams with deeper decks than the current allowable limit specified by design standards was also investigated. Using these deeper decks offers advantages such as faster and more cost-effective construction. One major challenge in creating an alternative test setup was eliminating the moment at the interface between the concrete-filled steel deck and the steel beam. This moment caused tension in the headed shear stud closest to the actuator, impacting the overall shear strength of the studs. Additionally, it was found that these shear studs show promising strength when used with 3.5 in. decks, but more research is needed to fully understand their capabilities. By exploring new test setups and considering deeper decks, this research contributes to improving the design and construction of composite beams, making them more efficient and reliable for future building projects.

A procedure is presented for using a primary resonance excitation in experimentally identifying the nonlinear parameters of a model approximating the response of a cantilevered beam by a single mode. The model accounts for cubic inertia and stiffness nonlinearities and quadratic damping. The method of multiple scales is used to determine the frequency-response function for the system. Experimental frequency- and amplitude-sweep data are compared with the prediction of the frequency-response function in a least-squares curve-fitting algorithm. The algorithm is improved by making use of experimentally known information about the location of the bifurcation points. The method is validated by using the parameters extracted to predict the force-response curves at other nearby frequencies. We then compare this technique with two other techniques that have been presented in the literature. In addition to the amplitude- and frequency-sweep technique presented, we apply a second frequency-domain technique and a time-domain technique to the second mode of a cantilevered beam. We apply the restoring-force surface method assuming no a priori knowledge of the system and use the shape of the surface to guide us in assuming a form for the equation of motion. This equation is used in applying the frequency-domain techniques: a backbone curve-fitting technique based on the describing-function method and the amplitude- and frequency-sweep technique based on the method of multiple scales. We derive the equation of motion from a Lagrangian and discover that the form assumed based on the restoring-force surface is incorrect. All of the methods are reapplied with the new form for the equation of motion. Differences in the parameter estimates are discussed. We conclude by discussing the limitations encountered for each technique. These include the inability to separate the nonlinear curvature and inertia effects and problems in estimating the coefficients of small terms with the time-domain technique. / Master of Science

<p dir="ltr">Road safety analysis typically relies on the correlation between road surface conditions, lane marking status, or lane width and crash data. Traditionally, this data is surveyed in the field after road construction or car accidents, which is labor-intensive, time-consuming, and hazardous. With the development of mobile mapping systems (MMS) in recent years, the ability to collect lane marking retroreflectivity or lane width information has been greatly improved. By utilizing Light Detection and Ranging (LiDAR) point clouds and RGB images captured by MMS, it is possible to establish lane marking inventory that includes the conditions of pavement markers (such as lane marking retroreflectivity and lane width) for road safety analysis.</p><p dir="ltr">This dissertation aims to develop a comprehensive framework to extract lane markings and report their characteristics using MMS datasets for transportation safety. The proposed approaches include geometric/morphological and deep learning-based approaches based on the LiDAR point clouds acquired by MMS. A normalization strategy is developed to ensure consistent intensity values across laser beams/LiDAR units/MMS for the same objects, thereby enhancing the lane marking extraction. In addition, an image-aided LiDAR approach is proposed to improve the extraction process further. Following the extraction, lane marking classification and characterization, including intensity profile generation and lane width estimation, are conducted to establish comprehensive lane marking inventory.</p><p dir="ltr">To evaluate the proposed strategies, lane marking extraction with and without intensity normalization is also conducted. The results show that the proposed intensity normalization significantly improves the performance of lane marking extraction, regardless of the approach or data used. The geometric approach using normalized intensity achieves F1-scores higher than 90%, outperforming the learning-based models. Furthermore, the intensity derived from two different MMS is compared for performance evaluation, and the agreement of normalized intensity values is within a range of 3.1 to 3.8 (the used MMS provide intensity as an integer number within 0 to 255). Through the normalization, a positive linear relationship between LiDAR normalized intensity and retroreflectivity is found, with the strongest relationship providing an R² of 0.72 and a Pearson's correlation coefficient of 0.85. A comparison of the correlation between original/normalized intensity and retroreflectivity revealed a stronger correlation between original intensity and retroreflectivity. For image-aided LiDAR approach, the image information indeed enhanced the LiDAR-based lane marking extraction approach, as evidenced by the highest F1-score (92.5%) of the image-aided LiDAR approach, outperforming the LiDAR-based (90.3%) and image-based (77.8%) ones. Specifically, the recall increases by 4.0% – from 87.6% (LiDAR-based) to 91.6% (image-aided LiDAR) – surpasses the slight improvement in the precision of 0.2% – from 93.2% (LiDAR-based) to 93.4% (image-aided LiDAR).</p><p dir="ltr">Finally, a Potree-based web portal is developed to visualize the results derived through the proposed lane marking extraction/classification/characterization strategies. This portal includes a function that enables the projection between 2D images and 3D point clouds, as well as tools for displaying intensity profiles and lane width estimates. It is capable of rendering a large dataset of {approximately 4.2 billion LiDAR points} in around ten seconds and allows for the visualization of intensity profiles and lane width estimates. Users can select points of interest in an intensity profile/lane width plot. This selection will result in the corresponding point being showcased in the LiDAR data on the web portal. Furthermore, the LiDAR point can be projected onto the corresponding image.</p><p dir="ltr">The above proposed strategies facilitate the investigation of the relationship between LiDAR intensity and mobile retroreflectivity. To ensure quality control, lane markings derived from geometric and learning-based extraction approaches were compared. These strategies were evaluated using two MMS (equipped with multiple imaging and LiDAR sensors), covering extensive road segments exceeding 400 miles. Furthermore, a reporting mechanism based on multi-modal data from various MMS sensors was implemented to visualize the results derived from the proposed strategies and to serve as a quality control tool. Consequently, the proposed strategies are easily adaptable for different MMS or the regular updating of lane marking inventory.</p>

No / Although computer architectures incorporate fast processing hardware resources, high performance real-time implementation of a complex control algorithm requires an efficient design and software coding of the algorithm so as to exploit special features of the hardware and avoid associated architecture shortcomings. This paper presents an investigation into the analysis and design mechanisms that will lead to reduction in the execution time in implementing real-time control algorithms. The proposed mechanisms are exemplified by means of one algorithm, which demonstrates their applicability to real-time applications. An active vibration control (AVC) algorithm for a flexible beam system simulated using the finite difference (FD) method is considered to demonstrate the effectiveness of the proposed methods. A comparative performance evaluation of the proposed design mechanisms is presented and discussed through a set of experiments.

This paper is concerned with the behaviour of beam ¿ column connections of steel ¿ concrete composite beams with precast hollow core slabs. Experiments were carried out to investigate the joint rotation characteristics and ultimate moment capacity of these connections. Details of the test specimens, instrumentation, test set-up and test procedures are described. Results obtained for the connection moment capacity, rotation capacity and failure modes are presented. It is found that through proper design and detailing, these simple steel connections display the characteristics of a semi-rigid connection with very little extra cost.

Yes / Although several research studies have been conducted on investigating the bond stress – slip behaviour of Glass-Fibre Reinforced Polymer (GFRP) bars embedded in high strength concrete (HSC) using a pull-out method, there is no published work on the bond behaviour of GFRP bars embedded in high strength concrete using a hinged beam. This paper presents the experimental work consisted of testing 28 hinged beams prepared according to RILEM specifications. The investigation of bond performance of GFRP bars in HSC was carried out by analysing the effect of the following parameters: bar diameter (9.5, 12.7 and 15.9 mm), embedment length (5 and 10 times bar diameter), surface configuration (helical wrapping with slight sand coating (HW-SC) and sand coating (SC)) and bar location (top and bottom). Four hinged beams reinforced with 16 mm steel bar were also tested for comparison purposes. The majority of beam specimens failed by pull-out. Visual inspection of the test specimens showed that the bond failure of GFRP (HW-SC) bars usually occurred owing to the bar surface damage, while the bond failure of GFRP (SC) bars was caused due to the detachment of sand coating. The GFRP bars with helical wrapping and sand coated surface configurations showed different bond behaviour and it was found that the bond performance of the sand coated surface was better than that of the helically wrapped surface. Bond strength reduced as the embedment length and bar diameter increased. It was also observed that the bond strength for the bottom bars was higher than that of the top bars. The bond strength was compared against the prediction methods given in ACI-440.1R, CSA-S806 and CSA-S6 codes. All design guidelines underestimated the bond strength of both GFRP re-bars embedded in high strength concrete. / Ministry of Higher Education in Libya for funding.

Yes / GFRP profiled-concrete composite beams with groove shear connectors are analyzed using finite the element (FE) analysis. The concrete damaged plasticity (CDP) model was adopted for normal strength concrete (NSC) and reactive powder concrete (RPC). The orthotropic behaviour of GFRP profile was taken into consideration, and the bi-linear traction-separation model was used to investigate the bond-slip behavior between GFRP profile and concrete. Furthermore, parametric studies were conducted to investigate the effects of strength and the cross-sectional dimensions of concrete, strength (orthotropy), and the cross-sectional dimensions (the web height and the thickness of FRP plate). Numerical analysis results correlate well with experimental results. Based on numerical analysis, the composite beam with shear connectors spacing at 100 mm has a deflection-limit load of 21.4 % higher than the specimens with 150 mm spacing. It is possible to improve the bonding behavior of interfaces by using groove shear connectors. The ultimate load and deformation, and pseudo-ductility were significantly improved by using RPC with high strength and toughness (ultimate compressive strain). GFRP profiles with greater orthotropy coefficients provide fully utilized concrete's compressive strength, preventing premature crushing and enhancing composite structure stiffness. Flexural performance of the composite beams can be improved efficiently by choosing the appropriate sectional size during design and construction. / The authors would like to thank the financial support provided by the Natural Science Foundation of Jiangsu Province, China (BK20201436), the Science and Technology Project of Jiangsu Construction System (2018ZD047, 2021ZD06), the Science and Technology Project of Gansu Construction System (JK2021-19), the Open Foundation of Jiangsu Province Engineering Research Center of Prefabricated Building and Intelligent Construction (2021), the High-End Foreign Experts Project of Ministry of Science and Technology, China (G2022014054L), the Science and Technology Cooperation Fund Project of Yangzhou City and Yangzhou University (YZU2022194, YZU212105), the Blue Project Youth Academic Leader of Colleges and Universities in Jiangsu Province (2020), the Science and Technology Project of Yangzhou Construction System (2022ZD03, 202204) and the Technology Innovation Cultivation Fund of Yangzhou University (2020-65).