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This paper investigated the analytical solution of the bond strength between ribbed steel bar and engineered cementitious composites (ECC). In this method, ECC cover was regarded as a thick‐walled cylinder subjected to the uniform internal pressure which consisted of an elastic uncracked outer ring and a partially cracked inner ring. For the uncracked outer ring, it can be solved by the elastic mechanics theory. To solve the partially cracked inner ring, two key problems that had to be investigated were the crack width and the tensile stress–crack width relationship of ECC. According to the steady‐state cracking mode, the hoop deformation of ECC was expressed by the equal distribution and then the crack width can be determined. Besides, the fictitious crack model in fracture mechanic was introduced to describe the crack propagation process. Then a trilinear model was applied to reflect the tensile stress–crack width relationship of ECC materials, which considered the combined action of aggregate bridging and fiber bridging on the crack surface. Finally, the comparison between the calculation results and experimental results was carried out to prove the validity of the analytic method of bond strength proposed in this paper. Results indicated that the analytical solution and the experimental data fitted in well with each other. Then parameter analyses were conducted based on the analytical method proposed in this paper. [ABSTRACT FROM AUTHOR]

This paper studies the chatter stability of composite cutter bar milling system in rotating coordinate frame. The main contribution of this paper is establishing a continuous distributed chatter analysis model for a composite cutter bar milling system in rotating coordinate frame. The stability of the milling system with a rotary symmetric dynamic cutter bar is predicted using the semi‐discrete time domain method. The effects such as internal damping, external damping, and symmetrical and asymmetric laminates on the stability of the milling system were analysed, and the results were compared between rotating and fixed coordinate frames. The results are consistent for symmetrical cutter bars in both the rotating and fixed coordinate frames. A new chatter instability zone appears at high rotating speeds due to the material internal damping of the rotating composite cutter bar. [ABSTRACT FROM AUTHOR]

Materials and structures are exposed to simultaneous fluctuations in temperature, pressure, and moisture in the environment, which result in additional stresses and strains in addition to mechanical loadings. This paper develops the effective coefficient of thermal expansion (CTE), coefficient of moisture expansion (CME), and compressibility for the interconnected array of ring and sliding rod structures made from conventional materials, wherein conditions that lead to negative thermal expansion (NTE), negative moisture expansion (NME) and negative compressibility (NC) -- and hence the negative environmental expansion (NEE) -- are established. The above-mentioned coefficients shift toward negative values as the ratio of ring-to-rod expansivity increases. The established effective CTE, CME, and compressibility not only permit the requirements for NTE, NME, and NC to be ascertained, but also allow the less restrictive condition of zero environmental expansion to be implemented in the design of materials and structures, without requiring zero CTE, CME, and compressibility. [ABSTRACT FROM AUTHOR]

Reinforced concrete bridges located in coastal environment are known to undergo structural degradation due to chloride-induced corrosion of reinforcement. In this paper, reliability-based methodologies have been formulated for safety assessment of in-service reinforced concrete T-girders against shear and cracking limit states. The proposed methodologies incorporate the following features: (a) gain in concrete compressive strength with time, (b) the time-dependent diffusion of chlorides into cover concrete, (c) the chloride-induced corrosion of both stirrups and main rebar of pitting type, (d) the corrosion current variation along the span, (e) the reduction in yield strength of stirrups after it starts corroding, and (f) corrosion crack formation due to the accumulation of the corrosion products. The system reliability concept is embedded in the framework of Monte Carlo simulation, for estimating the time-variant failure probabilities. The usefulness of the methodology is demonstrated on a typical in-service Chennai flyover, designed according to MORTH. The girder fails to meet the target reliability index consideration in the case of shear limit state and also fails the required serviceability criteria even before the end of 50 years. This example brings out the need to consider time-variant reliability considerations at the design stage itself. [ABSTRACT FROM AUTHOR]

The paper presents a non-local line method used to the fatigue life calculation of notched elements. The presented method is based on the concept of an effective length which determines the size of the equivalent fatigue zone. Effective values of normal stress calculated in the critical plane with a weight function were applied when determining the equivalent fatigue zone. Simulation studies were performed for two types of steel and two types of loading. Five different series of tests and simulations were used. Experimental studies were carried out for 40 HM-T and EA4T steels. These materials are used in railway industry, including the manufacturing of coupling bars. The notched test specimens contained notches with a tip radius of 0.2, 0.5, 0.8 and 1 mm. Stress calculations were performed using the finite element method by adopting cyclic material properties described by the model of a multi-linear hardening. Non-local calculations were performed in a defined critical plane for normal stress distribution and a weight function. As a result, the function of variation of the effective length depending on the loading level and geometry of the notch has been determined. [ABSTRACT FROM AUTHOR]

Progressive collapse is a phenomenon in which local failure of a structural component due to a gas explosion or blast may lead to failure of the entire structure or a significant part of it. RC structures can resist progressive collapse through various mechanisms such as frame action and catenary action. In this paper, the effect of catenary action on the resistance of concrete frame structures to progressive collapse is modelled using limit analysis. Non-linear optimization is performed for this. It is observed that although frame action is known to be the main mechanism resisting progressive collapse, at the end of this action, after rupture of bottom bars, catenary effects may bring about a noticeable increase in the resistance of the structure. The results show good agreement with the experimental results of other researchers. [ABSTRACT FROM AUTHOR]

This paper proposes an enhancement to the current strength and confinement-based design of transverse reinforcement in rectangular and circular reinforced concrete members to ensure that the flexural strength of reinforced concrete sections does not degrade excessively due to buckling of longitudinal bars until the desired level of plastic deformation is achieved. Antibuckling design criteria are developed based on a popular bar buckling model that uses a bar buckling parameter (combining the bar diameter, yield strength, and buckling length) to solely describe the bar buckling behavior. The value of buckling parameter that limits the buckling-induced stress loss to 15% in compression bars at the strain corresponding to the design ductility is determined. For a bar of known diameter and yield strength, the maximum allowable buckling length can then be determined, which serves as the maximum limit for the tie/stirrup/hoop spacing. Lateral stiffness required to restrain the buckling tendency of main bars at the locations of the ties/stirrups/hoops depends on the flexural rigidity of the main bars and the buckling length (equal to or multiple of tie/hoop/stirrup spacing), whereas the antibuckling stiffness (ie, resistance) provided by the ties/stirrups/hoops depends on their size, number, and arrangement. Using the above concept, design recommendations for the amount, arrangement, and spacing of rectangular and circular ties/stirrups/hoops are then established to ensure that the antibuckling stiffness of the provided transverse reinforcement is greater than the stiffness required to restrain the buckling-prone main bars. Key aspects of the developed method are verified using experimental tests from literature. [ABSTRACT FROM AUTHOR]

An experimental and analytical study on 15 specimens of lap splices embedded in nonconventional concrete without confining reinforcement was performed under direct tension. The experimental program involved two groups of straight‐ended and anchored‐ended bars; three different techniques were employed with different splice lengths. For straight‐ended bars, conventional lap splice was studied as a benchmark. The anchored‐ended steel bars were hooks, hooks intersecting with cross bars, and plate‐end bars. It was found that, the used techniques not only achieved higher tensile stress at failure, but also different modes of failure were observed. Besides, a splice length of five times bar diameter was found to be sufficient to achieve the nominal yield stress of the reinforcing steel bar in the case of anchored‐ended bars. Finally, an analytical model was proposed in order to predict the ultimate tensile stress of the straight‐ended spliced bars. The accuracy of the proposed model was verified against the test results of 137 existing specimens from previous research. The comparison showed good agreement between the results of the proposed model and the test results. [ABSTRACT FROM AUTHOR]

In this research project, a new type of fire resistant, stable and at the same time slender composite column is developed and analysed. For this purpose, a bunch of high‐strength reinforcing bars with a yield strength equal to 670 N/mm2 is inserted in a steel pipe and then grout injected. [ABSTRACT FROM AUTHOR]