The research provided in this report examines the behavior of fiber reinforced polymer (FRP) reinforcing bars, embedded in normal weight concrete (NWC) hinged beam-end specimens, tested in accordance with two laboratory conditions. Reinforcing bars of different diameter, material configuration, and finished surface preparation were tested for bond strength parameters determined in accordance with ACI Committee Report 440.3. Bond strength parameters under the first condition were tested within NWC beams at a relatively low compressive strength and minimum embedment length; the second condition allowed testing within NWC beams at twice the design compressive strength of the first condition and moderate embedment length. The load-slip curves developed show the differences that occur under the specified conditions. The influence of embedment length, bar diameter, material configuration, finished surface preparation, and concrete compressive strength are reported in detail. Furthermore, the testing arrangement selected for this study was proven to have a significant influence on bond behavior when compared to conventional pullout test methods.

Minimum requirements for lap splices in reinforced concrete members, stated in building codes of TS-500 and ACI-318, have a certain factor of safety. These standards have been prepared according to research results conducted previously and they are being updated according to results of recent studies. However the reliability of lap splices for minimum requirements needs to be investigated. For this purpose, 6 beam specimens were prepared according to minimum provisions of these standards. The test results were investigated by analytical procedures and also a parametric study was done to compare two standards. For smaller diameter bars both standards give safe results. Results showed that the minimum clear cover given in TS500 is insufficient for lap spliced bars greater than or equal to 26 mm diameter.

Laboratory test of reinforced and prestressed concrete structures have been used widely to explore the behavior of reinforced and prestressed concrete components and structures; Such tests are often time-consuming and costly. However, numerical models have been shown to compare favorably with experiments. Thus, computations are viewed nowadays as efficient alternatives to tests, time-wise and cost-wise. In the research reported in this thesis, finite-element model were used in a study of pretressed structural components in order to correlate levels of pretension with deflection and strain measurements. The two main objectives were to develop a suitable finite element model of prestressed concrete beams and to forecast beam prestension on the basis of deformations resulting from specified simple load, e.g., a uniformly distributed transverse load. A commercial finite-element analysis package (ANSYS 12) was used to set up, use and evaluate the computational model. Furthermore, a finite-difference model was employed in order to ascertain the validity of ANSYS results by comparison with engineering beam theory taking into account the applied pretension. This study demonstrates the potential usefulness of deflection and strain measurements as indicators of the pretension applied or remaining in prestressed concrete beams. / text

The Diploma thesis deals with the Diagnostics of Reinforced Concrete Bridge in the village of Luhačovice. This thesis also describes the individual Diagnostic methods and instruments used in purpose to make Diagnosis of bridge constructions. The main aim of the Diagnostics is to determine the current state of the Bridge which consists in verification of the actual road structure, determination of the physical and mechanical parameters of the Concrete (strength, depth of carbonation) and in some parts of the bridge structure to determine the type, number and position of the bending or shear reinforcement. Based on the evaluation of the laboratory tests a static calculation of the selected part of the Bridge structure is performed. The final evaluation is the determination of the load and the subsequent design of the necessary and recommended measures for maintaining or improving the functionality of the bridge structure.

No / The objective of this study was to evaluate the effect of corrosion level on shear behavior of engineered cementitious composite (ECC) beams. Reinforced normal concrete (R-NC) specimens with compressive strength equal to the ECC specimens were also used for control purposes. Ten reinforced concrete beams (five ECC and five NC) with dimensions of 150 x 220 x 1400 mm (5.91 x 8.66 x 55.12 in.) were manufactured for the study. Using accelerated corrosion through the application of a constant current of 1 ampere, four levels of corrosion were established at 5%, 10%, 15%, and 20% of mass loss of the reinforcing bars. To ensure the highest probability of shear failure mode, all beams were tested under a four-point loading system with a shear span-effective depth ratio of 2.5. General structural behavior, strength, stiffness, failure mode, and energy absorption capacities of ECC and R-NC beams subjected to different corrosion levels were evaluated and compared. Experimental results showed a high correlation between calculated mass loss and measured mass loss in reinforcing bars due to accelerated corrosion. Compared to NC, ECC beams exhibited significantly higher strength, stiffness, and energy absorption capacity, along with superior performance in terms of the restriction of damage caused due to corrosion. The increase in corrosion level negatively influenced the structural behavior of the ECC beams tested.

Yes / This paper numerically investigates flexural performance of Ultra-High Performance Concrete (UHPC) beam reinforced with Steel-Fibre-Reinforced Polymer (FRP) Composite Bars (SFCBs) in terms of flexural stiffness, moment capacity, deflection, ductility and energy dissipation. The effect of various parameters, include the inner steel core area ratio of SFCB, yield strength of inner steel core, elastic modulus and ultimate strength of outer-wrapped FRP, reinforcement ratio, type and strength of concrete were studied. The results demonstrate that the inner steel core area ratio of SFCB, reinforcement ratio and the elastic modulus of SFCB's outer FRP have significant effect on the overall flexural performance of SFCB reinforced UHPC beam. The overall flexural performance of SFCB reinforced UHPC beam is slightly improved by increasing the yield strength of inner steel core of SFCB, but not affected by the ultimate strength of SFCB's outer FRP when specimen occurred compression failure. The results also exhibit that the flexural performance of UHPC beam reinforced with SFCBs is significantly improved when compared to those of reinforced high strength concrete (HSC) beam and normal strength concrete (NSC) beam. The flexural stiffness and the moment capacity of SFCB reinforced UHPC beam at the ultimate point were 2.0 and 2.4 times, respectively, of those of reinforced NSC counterpart. / Natural Science Foundation of Jiangsu Province, China (BK20201436), the China Postdoctoral Science Foundation (2018M642335), the Science and Technology Project of Jiangsu Construction System, China (2018ZD047, 2021ZD06), the Science and Technology Project of Gansu Construction System, China (JK2021-19), the National Natural Science Foundation of China (51678514), the Science and Technology Innovation Fund of Yangzhou University, China (2020-65), the Open Foundation of Jiangsu Province Engineering Research Center of Prefabricated Building and Intelligent Construction, China (2021), the Science and Technology Cooperation Fund Project of Yangzhou City and Yangzhou University, China (YZU212105), the Practice and Innovation Plan for Postgraduates in Jiangsu Province, China (SJCX21_1589), the Blue Project Youth Academic Leader of Colleges and Universities in Jiangsu Province, China (2020) and the Deputy General Manager Science and Technology Project of Jiangsu Province, China (FZ20200869). References

Yes / Self-sensing concrete used in coating form for structural health monitoring of concrete structures has the merits of cost-effectiveness, offering protective effect on structural components, enabling electrical measurements unaffected by steel reinforcement and is also convenient to maintain and replace. This paper investigates the feasibility of using self-sensing cement mortar coating containing carbon nanotube-nano carbon black (CNT-NCB) composite fillers (CNCFs) for damage monitoring of concrete beams. The self-sensing cement mortar coated to concrete beams demonstrated outstanding electrical conductivity (resistivity ranging from 18 to 85 Ω·cm). Under monotonic flexural loadings, self-sensing cement mortar coating with 1.8 vol.% CNCFs featured sensitive self-sensing performance in terms of capturing the initiation of vertical cracks at pure bending span of concrete beams, with fractional change in resistivity (FCR) reaching up to 60.6%. Moreover, FCR variations of self-sensing cement mortar coating exhibited good synchronization and stability with the variation of mid-span deflections of concrete beams during cyclic flexural loadings irrespective of the contents of CNCFs and cyclic amplitudes. Remarkably, it was found that FCR of cement mortar coating basically showed a progressive upward tendency, representing irreversible increase in the resistance during cyclic loading. The irreversible residual FCR indicated the crack occurrence and damage accumulation of concrete beams.

Yes / Self-sensing concrete used in coating form for structural health monitoring of concrete structures has the merits of cost-effectiveness, offering protective effect on structural components, enabling electrical measurements unaffected by steel reinforcement and is also convenient to maintain and replace. This paper investigates the feasibility of using self-sensing cement mortar coating containing carbon nanotube-nano carbon black (CNT-NCB) composite fillers (CNCFs) for damage monitoring of concrete beams. The self-sensing cement mortar coated to concrete beams demonstrated outstanding electrical conductivity (resistivity ranging from 18 to 85 Ω·cm). Under monotonic flexural loadings, self-sensing cement mortar coating with 1.8 vol.% CNCFs featured sensitive self-sensing performance in terms of capturing the initiation of vertical cracks at pure bending span of concrete beams, with fractional change in resistivity (FCR) reaching up to 60.6%. Moreover, FCR variations of self-sensing cement mortar coating exhibited good synchronization and stability with the variation of mid-span deflections of concrete beams during cyclic flexural loadings irrespective of the contents of CNCFs and cyclic amplitudes. Remarkably, it was found that FCR of cement mortar coating basically showed a progressive upward tendency, representing irreversible increase in the resistance during cyclic loading. The irreversible residual FCR indicated the crack occurrence and damage accumulation of concrete beams. / National Science Foundation of China (52368031, 51978127 and 52178188) and the China Postdoctoral Science Foundation (2022M710973)

Sistemas mistos de aço e concreto são aqueles em que o elemento de aço trabalha estruturalmente em conjunto com o concreto. Essa associação dos materiais resulta numa melhor utilização de ambos os materiais tanto quanto à capacidade resistente, quanto em caráter construtivo, funcional e estético. O presente trabalho tem como finalidade a análise de vigas de aço e mistas de aço e concreto parcialmente revestidas em situação de incêndio. Esse estudo tem grande importância tendo em vista os incidentes com altas temperaturas em edificações ocorridos ao longo dos anos. O aumento de temperatura nas estruturas é um efeito nocivo, pois prejudica a rigidez e a resistência dos materiais, podendo levar estruturas ao colapso. As análises das vigas mistas aço e concreto parcialmente revestidas em situação de incêndio foram feitas através de análises experimentais que foram realizadas no forno horizontal à gás do Laboratório de Engenharia de Estruturas da EESC/USP. Foram realizados ensaios de flexão em pontos em altas temperaturas e a variável nos ensaios foi o fator de carga aplicado no meio do vão das vigas. Foi possível comparar o comportamento das vigas metálica e mistas, bem como as temperaturas em vários pontos ao longo do elemento por meio de termopares colocados em pontos estratégicos. Transdutores de deslocamento também foram usados para saber o valor de deslocamento nos apoios e no meio do vão das vigas. Uma análise térmica bidimensional através do ABAQUS também foi feita para comparação de resultados. Conclui-se que para uma mesma carga aplicada os deslocamentos foram mais expressivos nos ensaios das vigas em situação de incêndio se comparados aos valores obtidos nos ensaios à temperatura ambiente, observou-se o efeito benéfico do revestimento de concreto ao perfil metálico, responsável por um ganho expressivo de resistência ao fogo quando comparado aos elementos puramente metálicos e por fim obteve-se boa concordância entre as temperaturas encontradas por modelagem numérica através do ABAQUS e dos ensaios experimentais realizados. / Composite steel and concrete systems are those in which the steel element works structurally in conjunction with the concrete. This association of the materials results in a better use of both materials as much as the resistant capacity, as well as in a constructive, functional and aesthetic character. The present work has the purpose of analyzing steel beams and mixed steel and concrete partially coated in a fire situation. This study has great importance in view of the incidents with high temperatures in buildings that have occurred over the years. The increase in temperature in the structures is a harmful effect, as it impairs the rigidity and the resistance of the materials, which can lead to collapse structures. The analyzes of the composite steel and concrete composite beams in a fire situation were made through experimental analyzes that were carried out in the horizontal gas furnace of the Laboratory of Structural Engineering of EESC/USP. Bending tests were performed on points at high temperatures and the variable in the tests was the load factor applied in the middle of the span of the beams. It was possible to compare the behavior of the metallic and composite beams as well as the temperatures at various points along the element by means of thermocouples placed at strategic points. Displacement transducers were also used to know the displacement value in the supports and in the middle of the span of the beams. A two-dimensional thermal analysis through ABAQUS was also done for comparison of results. It was concluded that for the same applied load the displacements were more expressive in the tests of the beams in the fire situation compared to the values obtained in the tests at room temperature, the beneficial effect of the concrete coating was observed on the metallic profile, responsible for a an expressive gain of fire resistance when compared to the purely metallic elements and finally a good agreement was obtained between the temperatures found by numerical modeling through ABAQUS and the experimental tests performed.

Sistemas mistos de aço e concreto são aqueles em que o elemento de aço trabalha estruturalmente em conjunto com o concreto. Essa associação dos materiais resulta numa melhor utilização de ambos os materiais tanto quanto à capacidade resistente, quanto em caráter construtivo, funcional e estético. O presente trabalho tem como finalidade a análise de vigas de aço e mistas de aço e concreto parcialmente revestidas em situação de incêndio. Esse estudo tem grande importância tendo em vista os incidentes com altas temperaturas em edificações ocorridos ao longo dos anos. O aumento de temperatura nas estruturas é um efeito nocivo, pois prejudica a rigidez e a resistência dos materiais, podendo levar estruturas ao colapso. As análises das vigas mistas aço e concreto parcialmente revestidas em situação de incêndio foram feitas através de análises experimentais que foram realizadas no forno horizontal à gás do Laboratório de Engenharia de Estruturas da EESC/USP. Foram realizados ensaios de flexão em pontos em altas temperaturas e a variável nos ensaios foi o fator de carga aplicado no meio do vão das vigas. Foi possível comparar o comportamento das vigas metálica e mistas, bem como as temperaturas em vários pontos ao longo do elemento por meio de termopares colocados em pontos estratégicos. Transdutores de deslocamento também foram usados para saber o valor de deslocamento nos apoios e no meio do vão das vigas. Uma análise térmica bidimensional através do ABAQUS também foi feita para comparação de resultados. Conclui-se que para uma mesma carga aplicada os deslocamentos foram mais expressivos nos ensaios das vigas em situação de incêndio se comparados aos valores obtidos nos ensaios à temperatura ambiente, observou-se o efeito benéfico do revestimento de concreto ao perfil metálico, responsável por um ganho expressivo de resistência ao fogo quando comparado aos elementos puramente metálicos e por fim obteve-se boa concordância entre as temperaturas encontradas por modelagem numérica através do ABAQUS e dos ensaios experimentais realizados. / Composite steel and concrete systems are those in which the steel element works structurally in conjunction with the concrete. This association of the materials results in a better use of both materials as much as the resistant capacity, as well as in a constructive, functional and aesthetic character. The present work has the purpose of analyzing steel beams and mixed steel and concrete partially coated in a fire situation. This study has great importance in view of the incidents with high temperatures in buildings that have occurred over the years. The increase in temperature in the structures is a harmful effect, as it impairs the rigidity and the resistance of the materials, which can lead to collapse structures. The analyzes of the composite steel and concrete composite beams in a fire situation were made through experimental analyzes that were carried out in the horizontal gas furnace of the Laboratory of Structural Engineering of EESC/USP. Bending tests were performed on points at high temperatures and the variable in the tests was the load factor applied in the middle of the span of the beams. It was possible to compare the behavior of the metallic and composite beams as well as the temperatures at various points along the element by means of thermocouples placed at strategic points. Displacement transducers were also used to know the displacement value in the supports and in the middle of the span of the beams. A two-dimensional thermal analysis through ABAQUS was also done for comparison of results. It was concluded that for the same applied load the displacements were more expressive in the tests of the beams in the fire situation compared to the values obtained in the tests at room temperature, the beneficial effect of the concrete coating was observed on the metallic profile, responsible for a an expressive gain of fire resistance when compared to the purely metallic elements and finally a good agreement was obtained between the temperatures found by numerical modeling through ABAQUS and the experimental tests performed.