[en] In a Reinforced Concrete (R.C) structure, major reinforcement is used for taking up tensile stresses acting on the structure due to applied loading. The present paper reports the behavior of reinforced concrete beams with helical reinforcement (transverse reinforcement) subjected to monotonous loading by 3-point flexure test. The results were compared with identically similar reinforced concrete beams with rectangular stirrups. During the test crack evolution, load carrying capacity and deflection of the beams were monitored, analyzed and compared. Test results indicate that the use of helical reinforcement provides enhanced load carrying capacity and a lower deflection proving to be more ductile, clearly indicating the advantage in carrying horizontal loads. An analysis was also carried out using ANSYS software in order to compare the test results of both the beams. (paper)

[en] Research providing guidance on management of aging reinforced concrete structures is summarized. Topics covered include a materials property database, an aging assessment methodology to identify critical structures and degradation factors that can potentially impact performance, guidelines and evaluation criteria for use in condition assessments, and a reliability-based methodology for current condition assessments and estimations of future performance. Applicability of nondestructive evaluation and repair-related technologies is addressed

[en] Experimental study aimed at evaluation of static preload impact on concrete strength and deformation characteristics had been carried out in 2014–2017 in laboratory of Strength of Materials Department of Moscow State Institute of Civil Engineering. The paper briefly presents the research technique, outcome and suggests its interpretation. Authors’ feature of the methodology is an absence of unloading when applying the dynamic load with stress growth rate of 450 MPa/sec and destruction time of approximately 0.8 sec after static preload with value of 0.3, 0.7 and 0.8 of prism strength. The use of portable dynamic module which was has been designed and built by Igor Bezgodov, engineer of Moscow State University of Civil Engineering, made it possible to complete the experiment. Investigation of samples under short- term static load of the same level and reference samples under static and dynamic load without preloading was carried out concurrently. The data obtained include strength values and stress-strain diagrams which allowed estimating the coefficients of longitudinal and transverse deformation and ultimate deformation. The authors suggest that long-term static preload does not affect the dynamic strengthening factor, which remained between 1.17 and 1.30 regardless of preload level. At the same time preloading changes stress-strain diagram significantly. Diagrams for various loading modes are combined on single figure to demonstrate their features. The coefficients of longitudinal and transverse deformation related to significant fragments of diagrams are presented in tables and compared to each other. Loading rate considerably lowers ultimate deformations under dynamic impact. Relatively low-level preloading does not modify longitudinal deformations perceptibly, however, at preloading level of 0.8 longitudinal deformations increase significantly and almost match the ones under static loading. The authors conclude that comparison of diagrams points out on necessity of taking deformation rate growth and static preload level into consideration in practical calculations of concrete and reinforced concrete constructions. Thus, the research contributes to the development of computational models of concrete and reinforced concrete. (paper)

[en] The increase in construction activity in the Philippines, reinforced concrete building is still a favorite among designers, because it is much cheaper to build and it requires qualified welders, etc. and extensive nondestructive testing and inspection of metals, welds and castings. Of all the techniques radiography is widely used for concrete

[en] The paper presents a theoretical study of the structural resistance of short compressed concrete elements in a glass-fiber reinforced shell. The methodology is based on a nonlinear strain model of how this element reacts to incremental loading. What makes computing such structures difficult is the need to account for the continuously changing lateral shell pressure on the concrete core. Lateral pressure keeps increasing due to changes in the concrete-core and glass fiber-reinforced shell lateral-strain coefficients, causing greater stress in the material. This paper is the for to propose formulas to account for such changes and measure lateral pressure for any load on such a structure. It also outlines practical guidelines on computing the strength of short compressed concrete elements in a glass fiber-reinforced shell. (paper)

[en] Highlights: • Experimentally tested RC beams under blast are analyzed using Timoshenko beam model. • Shear demand to shear capacity ratio is the influential parameter to control failure mode. • Change in beam failure mode with variation of blast load and/or longitudinal reinforcement. • Maximum moment to ultimate moment resistance ratio cannot predict the failure of the current test beams. - Abstract: In this study the dynamic response of Reinforced Concrete (RC) beams was experimentally evaluated under blast loading. Eighteen beams were field tested using 40 to 250 kg charges of ANFO explosive detonated at a ground standoff distance of 10 to 30 m. Other test parameters included variation of transverse and longitudinal reinforcements. Blast wave characteristics, displacement and strain histories were measured, and the post-blast damage and mode of failure of the test specimens were observed. Results showed change in failure mechanism with variation of blast load scaled distance, and/or longitudinal reinforcement. To simulate the observed responses of the test beams and investigate the relationship between the initial forces and deformations developed in RC beams due to blast loading and the associated failure modes, beams were modeled using the Timoshenko beam theory. It was determined that beam deformations in the initial phase of a blast induced response cycle were dominated by shear. The ratio of shear demand to shear capacity, the latter computed based on the Canadian Standard CAN/CSA A23.3, was deemed to be the most influential parameter that governed the failure mechanism. In addition, assuming a deformed shape based on static loading resulted in underestimating the shear demand, which, in turn, could lead to inaccurate predictions of the failure mechanism.

[en] In order to improve the seismic resistance of existing anti-seismic wall of nuclear facility, a reinforcement method is considered in which after adding wall reinforcing bars on one side of the existing wall, concrete is additionally placed and integrated. In this reinforcement method, there is a jointing surface between the existing body and the reinforcing body, and in order to confirm the structural performance when in-plane and out-of-plane shearing forces act on this jointing surface, a static loading test was carried out with a simple beam form using a simulated test body. The test samples are those with different treatment methods on the connecting surface and one for comparison with a monolithic structure. As a result of the experiment, it was confirmed that the difference in the treatment methods of the joint surface had little effect on the yield strength and the deformation performance, showing almost the same values as the case of the monolithic structure. (A.O.)

[en] Evaluation of existing nuclear facility structures must be conducted with the appropriate level of conservatism. Therefore, even though modern performance-based evaluation procedures for conventional structures are available, they must be rigorously examined before they are used to evaluate nuclear facility structures. This paper presents selected results of an evaluation of various nonlinear static and dynamic demand analysis and FEMA-356 capacity measures on a test-bed nuclear facility reinforced concrete frame structure built in 1960's. It is shown that these modern procedures can be used. Furthermore, they revealed deficiencies of the test-bed structure that could not be easily found using the conventional linear-and-elastic evaluation methods. Nevertheless, more work is needed to calibrate these new procedures for the risk reduction levels required for nuclear facilities before they can be used in nuclear facility design and evaluation practice. (author)

[en] This research presents a structural design of high-level waste (HLW) container using ultra-high performance fiber reinforced concrete (UHP-FRC) material. The proposed design aims to overcome the drawbacks of the existing concrete containers which are heavy, difficult to fabricate, and expensive. In this study, the dry storage container (DSC) that commonly used at Canadian Nuclear facilities is selected to present the proposed design. The design has been performed such that the new UHP-FRC alternative has a structural stiffness equivalent to the existing steel-concrete-steel container under various loading scenarios. Size optimization technique is used with the aim of maximizing stiffness, and minimizing the cost while satisfying both the design stresses and construction requirements. Then, the integrity of the new design has been evaluated against accidental drop-impact events based on realistic drop scenarios. The optimization results showed: the stiffness of the UHP-FRC container (300 mm wall thick) is being in the range of 1.35–1.75 times the stiffness of existing DSC (550 mm wall thick). The use of UHP-FRC leads to decrease the container weight by more than 60%. The UHP-FRC container showed a significant enhancement in performance in comparison to the existing DSC design under considered accidental drop impact scenarios

[en] In this paper we describe the technique of reinforced concrete tomography, its historical background, recent technological developments and main applications. Gamma radiation sensitive plates are imprinted with radiation going through the concrete sample under study, and then processed to reveal the presence of reinforcement and defects in the material density. The three dimensional reconstruction, or tomography, of the reinforcement out of a single gammagraphy is an original development alternative to conventional methods. Re-bar diameters and positions may be determined with an accuracy of ± 1 mm 0.5-1 cm, respectively. The non-destructive character of this technique makes it particularly attractive in cases of inhabited buildings and diagnoses of balconies. (author)