Search

Existing studies have proved that interfaces between the prefabricated layer and the cast‐in‐place layer significantly affect the static performance of prefabricated concrete structures using the wet connection method, but little has been known about the fatigue performance, especially at high load levels. This study investigated the fatigue behavior of prefabricated composite concrete beams under negative bending moment induced by the high‐stress level cyclic load. Fifteen composite T‐beams with three different designed sections were tested. The failure mode, cracking and deflection behavior, steel strain development, and the new‐old concrete interfacial deformation were recorded and analyzed. It was found that the stress redistribution occurred with the debonding cracks generated at the new‐old concrete interface, causing the degradation of the static and fatigue performance. Setting interfacial shear keys could prevent such debonding failure at static and low cyclic loading levels. Meanwhile, the corresponding mechanisms were verified through cross‐sectional analysis. [ABSTRACT FROM AUTHOR]

The dual‐function retrofitting system that uses the carbon‐fabric reinforced cementitious matrix (C‐FRCM) as both the anode of impressed current cathodic protection (ICCP) system and the structural strengthening (SS) material, that is, an ICCP‐SS system, is investigated. The experimental program mainly focused on the shear behavior of C‐FRCM strengthened reinforced concrete (RC) continuous beam under the dual‐function retrofitting system. The influence of anode polarization on the shear strengthening of RC continuous beams is analyzed. Shear tests were conducted on a total of 14 corroded RC continuous beams to investigate the influence of key parameters, including anode polarization degree of prefabricated C‐FRCM plate, layer of carbon fiber mesh and side‐wrapping. The failure modes, shear capacities, and load‐deflection curves of the shear‐strengthened RC continuous beams are reported. Based on the test results, the applicability of relevant design codes was evaluated and found to provide rather conservative predictions for the shear capacity of the examined C‐FRCM strengthened RC continuous beams. [ABSTRACT FROM AUTHOR]

The goal of this study is to propose a robust method for the analysis and design of recycled aggregate reinforced concrete (RAC) beams. For this purpose, a machine‐learning framework, named, GA‐XGBoost was designed. A comprehensive dataset of 276 tests of RAC beams was compiled from available literature for training, validating, and testing the models. The results confirmed that the proposed models can offer a precise tool for failure mode classification and capacity prediction of RAC beams. For the design framework, a Generative Adversarial Network for tabular data was utilized to produce synthetic data. These synthetic data can provide options for the selection of design variables. In this framework, the design variables are selected by specifying the design constraints, the objective function to be optimized, and validating the capacity requirements using the developed GA‐XGBoost models. Lastly, a web application was developed to make the proposed GA‐XGBoost models appropriate for practical design. [ABSTRACT FROM AUTHOR]

This paper presents an experimental investigation into the flexural and cracking behavior of corroded reinforced concrete continuous beams with 11‐month wet–dry cycles strengthened by anodic polarized carbon‐fabric‐reinforced cementitious matrix (C‐FRCM) plates. The failure modes and flexural bearing capacities were discussed. The influences of the layer of carbon fabric mesh and complete carbon fiber‐reinforced polymer (CFRP) wrapping as end anchorage on the strengthening effectiveness were explored. The complete crack development patterns were captured by a digital image correlation system, and the results showed that the C‐FRCM system can provide satisfactory crack width control, as proved by the reduced crack spacing and the maximum crack width. The flexural capacities of the strengthened beams were effectively enhanced and the debonding failure can be eliminated through complete CFRP wrappings. Moreover, the design recommendations were proposed based on the estimation of the crack development as per related design guidelines. [ABSTRACT FROM AUTHOR]

Ductility is one of the most important requirements of RC design besides other requirements such as strength and stiffness. In recent years, concrete beams with a large amount of tensile reinforcement ratio (ρ) have been required in large projects, such as high‐rise buildings and bridges. Using high (ρ) increases the strength and stiffness of the beams and leads to a decrease the ductility. This paper aimed to investigate the effect of using steel fibers reinforced concrete (SFRC) layer in compression zone on the flexural behavior of over‐reinforced concrete beams. Partial replacement of concrete with SFRC layer in compression zone was used to avoid the brittle compression failure of concrete. For this purpose, 12 over‐reinforced concrete beams with a span of 1300 mm and a cross‐section of 120 mm × 180 mm were cast and tested under a three‐point loading. The first beam was used as a reference beam and others as strengthened beams using SFRC layer. The effects of thickness and length of strengthening layer, (ρ), volume fractions of steel fibers, and strengthening methods on flexural performance of tested beams were investigated. The flexural capacity, failure modes, crack patterns, load–deflection relationships, load–strain relationships, ductility index, and toughness were evaluated. The results showed that the suggested technique (SFRC layer in the compression zone) is an effective technique to increase ultimate load, ductility, and toughness by up to 35.72%, 121.01%, and 349.16%, respectively, compared to the reference beam. Furthermore, the failure mode changed from brittle to ductile failure. Also, one of the main advantages of this technique is allows to increase of (ρ) up to 8.55% (4.15ρb) without needing the compressive reinforcement. The results of this study indicate that the using SFRC layer in the compression zone is an appropriate and economical method to provide high flexural capacity and ductility over‐reinforced concrete beams. [ABSTRACT FROM AUTHOR]