Papers by Keyword: Cyclic Loading

Abstract: This study presents a comparative evaluation of four steel beam-to-column connection configurations—Conventional (CONV), Cover Plate (CP), Reduced Beam Section (RBS), and a hybrid Reduced Beam Section with Cover Plate (RBSCP)—under cyclic loading conditions, with particular emphasis on hysteresis behavior and energy dissipation capacity. Finite element simulations were performed up to 6% story drift to evaluate each model’s performance against the seismic demand limits prescribed in ASCE/SEI 41-17. All configurations demonstrated adequate ductility for moderate to severe seismic events. The CONV model underperformed in both energy dissipation and stiffness retention, producing narrower hysteresis loops and exhibiting earlier stiffness degradation. In contrast, the CP connection achieved the highest energy dissipation and moment strength at all drift levels, attributed to the increased flange stiffness from the cover plates. The RBS model exhibited stable, well-balanced hysteresis loops with slightly lower strength but effective energy dissipation, benefiting from the intentional relocation of the plastic hinge away from the column face. The RBSCP connection combined the advantages of strength and ductility, sustaining broad and stable hysteresis loops with minor asymmetry between the positive and negative directions. Although it did not surpass CP in peak strength, RBSCP offered a well-balanced seismic performance. Envelope curve analysis revealed distinct differences in stiffness and degradation patterns. These findings highlight the potential of hybrid configurations such as RBSCP, with further geometric optimization recommended to enhance consistency and reliability.

Abstract: This paper introduces a novel fatigue failure criterion that leverages the evolution of residual stresses under cyclic loading to more accurately predict fatigue life in advanced materials. Traditional fatigue models often overlook the dynamic nature of residual stresses, which can significantly influence crack initiation and propagation. The proposed criterion incorporates a combination of experimentation and mathematical modeling to capture the complex interplay between cyclic loading, material microstructure, and fatigue damage. The criterion's effectiveness is validated through a series of fatigue tests on representative materials, demonstrating its superior predictive capability compared to conventional methods. This research offers a new paradigm for fatigue analysis, enabling more reliable design and performance assessment of critical components in various engineering applications.

Abstract: In the realm of civil engineering, scientists and engineers are striving to enhance the performance of Portland cement concrete (PCC) by incorporating organic waste materials, particularly wheat straw fibers. These fibers, alongside polymers, are key components in reinforcing cementitious concrete. They have been extensively studied and found to positively impact plain concrete, leading to the development of fiber-reinforced concrete (FRC). This study innovates construction through unique random fiber inclusion, diverse types, and addressing maintenance overlays of rigid pavements. This concept resembles a two-sided coin, with one side involving the random integration of fibers into the matrix, commonly seen in applications like Portland cement concrete pavement slabs and canal lining. Extensive research efforts were undertaken to gather insights into the significance of fiber composites in the field of construction. This literature review examines papers published by well-regarded publishers, encompassing the latest and essential research findings. Consequently, the primary aim of this study is to consolidate the outcomes and hurdles associated with fiber-reinforced composites for rigid pavement overlays, offering practical solutions to optimize concrete for enhanced pavement performance and sustainability. Our study's primary goal is to investigate the alterations in wheat straw fiber-reinforced concrete (WSFRC) materials through random fiber inclusion and explore the implications of different fiber types, mixing procedures, and construction challenges. A comprehensive literature review reveals three main objectives for incorporating fibers into concrete pavement overlays: enhancing mechanical properties, developing electrically conductive mixtures, and providing a sustainable solution for waste fiber management. This research paves the way for improving the performance and sustainability of concrete pavements in civil engineering.

Abstract: The wood has been focused for sustainable development goals (SDGs) of many interior products and buildings. The durability and weatherability of wood as constituent material should be investigated for the safety. In this study, the fatigue test of Japanese cedar as wood was conducted after and before outdoor exposure tests for constituent materials of interior products and buildings. The test term is one month (start time: 9/7/2020). The test place for outdoor exposure test is Hino Tokyo, Japan. As a fatigue test condition, the frequency was 10 Hz. The stress level was 70-90% of the tensile strength. As a result, the fatigue property of Japanese cedar was affected by photo degradation because constituent materials on the surface of Japanese cedar mainly received ultraviolet wave under outdoor exposure environment.

Abstract: Nowadays, as a response to the promoted concept of performance-based seismic design, the finite element method (FEM) has become an omnipresent practice that supports the simulation of structural elements. This approach requires constitutive numerical models, which could reproduce both elastic and plastic behaviour of steel. Looking forward to a reliable FEM simulation, the modelling and calibration of steel undergoing monotonic and cyclic loading tests is investigated in this paper. With respect to monotonic tensile test, a sensitivity analysis regarding mesh refinement and finite element type is developed. Another inspected issue, such as high-strength steel modelling, taking into consideration low ductility and absence of yield plateau, is also presented. And finally, a model for structural steel, using the combined isotropic-kinematic hardening model, is introduced to simulate metal non-linear behaviour under ultra-low-cycle fatigue regime. All these numerical simulations are processed via Abaqus software package, and are validated by a set of experimental tests.

Abstract: The change in the coercive force of the 10kp5 steel specimens subjected to cyclic loading and impulse current has been studied. The choice of processing methods, including their combination in a certain sequence, was shown to provide the best plastic or strength properties of metal materials. The feasibility and good perspectives of express assessment of the effectiveness of the chosen method or methods of processing metal materials by magnetic properties, e.g., coercive force, without resorting to mechanical tests with the destruction of specimens, are noted. The highest changes towards increase in strength and coercive force in the 10kp5 low-carbon steel have been found after cyclic loading and in a combined mode with cyclic loading at the final stage. The optimal combination of cyclic loading and pulse current can make it possible to control the strength and magnetic properties of ferromagnetic materials.

Abstract: The paper shows results of studying the effect of zero-to-tension cycling, with an amplitude approximately corresponding to the conventional yield strength, and subsequent static elastic tension along the same direction on the behavior of magnetostriction and differential magnetic permeability of low-alloy structural 08G2B steel. The behavior of the studied magnetic characteristics under static tension confirms the inference that the level of residual compressive stresses induced by cyclic preloading increases along the axis of cyclic tension.

Abstract: This paper presents a novel direct method called the stress compensation method (SCM) for structural shakedown analysis. Being different from the popular direct method of mathematical programming, the SCM just carries out some iterative calculations. Making full use of static shakedown theorem, the residual stress field is constructed via solving the modified global equilibrium equations. An effective and robust iteration control technique is adopted to generate a sequence of decreasing load multipliers. The numerical procedure is incorporated into the ABAQUS platform via some user subroutines. The shakedown problems for a cantilever beam, a symmetric continuous beam and a practical shell with nozzles are effectively solved and analyzed. These results are compared to the analytical solutions and those found in literatures. Both the incremental collapse mechanism and the alternating plasticity mechanism are revealed to determine the shakedown boundaries. Numerical examples show that the SCM is of numerical stability, good accuracy, high computational efficiency, and can effectively perform shakedown analysis of large-scale practical engineering structures.

Abstract: The progress of civilization has been led to the increase of industrial products, the amount of waste is increasing, and its disposal has become a problem. And, the huge amount of expended concrete has led to the dissipation of natural aggregate. To deal with these problems, many researches have been executed to use a variety of industrial waste as aggregate in concrete materials. So, in this paper, the flexural behavior with substitution ratio of heavyweight waste glass were compared and evaluated in reinforced concrete members. From the results, initial cracking load, yielding load and flexural rigidity less affected by substitution ratio of heavyweight waste glass. However, the ductility of the RC member was significantly affected when all of the fine aggregate is replaced by the heavyweight waste glass.

Abstract: Lower cold rolling reductions before reversion annealing for the grain size refinement are desired in industrial practice. This study demonstrates the effect of a low (32%) cold rolling reduction on cyclic behavior of a partially reversed (750 °C for 0.1s) structure in a 17Cr-7Ni-N type 301LN austenitic stainless steel and compares it with those of a 63% cold rolled and annealed and with a conventional coarse-grained structure. Stress amplitude and the amount of deformation-induced martensite formed under cyclic loading at the 0.6% total strain amplitude were recorded. The results showed that the partially reversed structure after the 32% cold rolling reduction exhibits the similar cyclic stress amplitude level and slight cyclic hardening as the 63% cold-rolled counterpart does. Even though the grain size refinement remains less effective at the lower reduction, the microstructure consists of higher fractions of strong retained cold-deformed austenite and martensite phases which increase the flow resistance. However, the coarse-grained structure exhibits a much lower initial stress amplitude and much more pronounced cyclic hardening. The susceptibility of austenite to transform deformation-induced martensite is practically similar among these three structures. However, the cyclic hardening is a caused by the formation of deformation-induced martensite, and the difference in the degree of cyclic hardening results from the big difference in the strength of the austenite between the partially reversed fine-grained and coarse-grained structures.