yes / This paper presents an analytical procedure based on the stiffness matrix method for deflection prediction of concrete structures reinforced with fiber reinforced polymer (FRP) bars. The variation of flexural stiffness of cracked FRP reinforced concrete members has been evaluated using various available models for the effective moment of inertia. A reduced shear stiffness model was also employed to account for the variation of shear stiffness in cracked regions. Comparisons between results obtained from the proposed analytical procedure and experiments of simply and continuously supported FRP reinforced concrete beams show good agreement. Bottom FRP reinforcement at midspan section has a significant effect on the reduction of FRP reinforced concrete beam deflections. The shear deformation effect was found to be more influential in continuous FRP reinforced concrete beams than simply supported beams. The proposed analytical procedure forms the basis for the analysis of concrete frames reinforced with FRP concrete members.

This report deals with the influence of different sizing agents on carbon fiber (CF) heavy tows towards their impregnation with a geopolymer (GP) suspension and resulting properties of mineral-impregnated carbon-fiber composites (MCF) produced in an automated, continuous process. Three different commercial CFs were investigated after treatment with either thermoplastic, epoxy, or vinyl-ester sizing agents and then compared to unsized CFs. During impregnating, diverse yarn-spreading behavioral modes and degrees of wetness were observed, indicating different degrees of impregnation, both in quality and quantity. All sizing agents decreased the hydrophobic nature of unsized CFs significantly. Supported by microscopic investigation, water contact angle measurement, and thermal gravimetric and mercury intrusion porosity, the epoxy sizing showed the best fiber-matrix distribution over the cross-section and a dense microstructure. Moreover, in single-fiber pullout tests each sizing brought about a significant increase in maximum pullout force, indicating enhanced bond between fiber and matrix. This is attributed to more intense interaction in the interfacial region, fully corroborating the topological characteristics obtained in microscopic analysis. With higher interfacial bond strength, the thermoplastic sizing enabled the highest tensile properties of MCF despite slightly less impregnation quality in comparison with epoxy-sized samples.:Abstract Keywords 1. Introduction 2. Materials and methods 2.1. Raw materials 2.2. Preparation of the mineral-impregnated carbon fiber composites (MCF) 2.3. Single-fiber pullout tests 2.4. Characterization of fresh state properties of MCF 2.5. Mechanical testing of MCF 2.6. Analytical and morphological characterization 3. Results and discussion 3.1. Characterization of CF yarns 3.2. Characterization of yarn processing 3.3. Morphological and analytical characterization of MCF 3.4. Bending behavior of MCF 3.5. Pullout behavior of carbon fibers 3.6. Uniaxial tensile behavior of MCF 3.7. Microscopic analysis of the fracture surfaces of MCF 4. Summary and conclusions CRediT authorship contribution statement Declaration of Competing Interest Acknowledgment References