Investigation on Residual Compressive Distribution of High-Strength Steel for Bridges by Base Metal Hammer Impact Peening

Various peening techniques have been used to improve the fatigue strength of steel structures. Among them, base metal impact hammer peening shows significant improvement in fatigue strength in ordinary steel, but the effect on high-strength steel has not been sufficiently studied. Accordingly, this study applied base material hammer impact peening to test specimens of 780 MPa grade high-strength steel (HT780) and 490 MPa grade ordinary steel (SM490), and the residual stress was measured and simulated. The experimental results clarified that a large compressive residual stress was introduced into the inner part of the plate thickness near the indentation in the high-strength steel, although the range of introduction of residual stress was equivalent in both the ordinary steel and high-strength steel.

Electrochemical study and characterization of tin coatings with and without glucose-based additive

<p>The tin coating was elaborated electrolytically on an ordinary steel substrate in SnSO₄ based electrolyte in acid medium with additive (bis-glycobenzimidazolone) at ambient temperature. The pH is maintained at 1.2±0.2 Bis-glycobenzimidazolone influence on the electrochemical properties of the tin coating was investigated using stationary polarization, chronopotentiometry, and cyclic voltammetry techniques. These studies show an apparent decrease in cathodic peak current and a drop in potential. The deposition rate also decreases as the concentration of the additive increases. SEM (Scanning Electron Microscopy) observation and XRD (X-ray Diffraction) analysis showed that the coating consists of good surface quality of the deposit elaborated by the addition of an optimal concentration of bis-glycobenzimidazolone (10^-3M) in the electrolyte, which constitutes the continuation of a preliminary study.<strong></strong></p>

Research Progress and Engineering Applications of Stainless Steel-Reinforced Concrete Structures

The durability of concrete structures can effectively be enhanced by using stainless steel rather than ordinary steel reinforcements under harsh service conditions. Because the basic mechanical properties and stress-strain relationship of stainless steel reinforcements obviously differ from those of ordinary steel reinforcements, the current design codes for reinforced concrete structures are not appropriate for stainless steel-reinforced concrete. On the basis of the research works reported in the past decades, this paper systematically summarizes and analyzes the mechanical properties and corrosion resistance of stainless steel reinforcements, the properties of the bond between stainless steel reinforcements and concrete, the mechanical properties of stainless steel-reinforced concrete members, and the application of stainless steel reinforcements in practical engineering and proposes relevant problems which should be examined further. It is suggested that the design theory of stainless steel-reinforced concrete structures should be further improved to take full advantage of these structures.

Cement-Based Mortar Panels Reinforced with Recycled Steel Fibers in Flexural Strengthening of Concrete Beams

The effectiveness of a strengthening technique devised for the concrete beams subjected to bending is presented in this study, where recycled-steel fiber-reinforced mortar (RSFRM) panels are used as an eco-friendly replacement for ordinary steel fibers. Different mix designs for RSFRM are first investigated experimentally by testing 160 × 400 × 400 mm3 notched beam-like specimens in 3-point bending, while 100 × 100 × 100 mm3 cubes are tested in compression, to optimize the mix design. Finite element (FE) analyses are carried out on strengthened and non-strengthened beams to investigate the effectiveness of the proposed strengthening technique based on RSFRM panels. Starting from the tests on notched beams, an inverse FE analysis is used to optimize the RSFRM’s parameters to be implemented into the numerical model. The results show that applying RSFRM panels not only markedly increases the load-bearing capacity of the beams (up to 3.19 times with 3% of fibers by volume), but also changes their fracture mechanism from brittle to ductile fracture.

Application of Buckling Restrained Braces to Upgrade Vertical Stiffness of Existing RC Frames

In this paper, based on the RC frame structure of an industrial building, the finite element model of the structure is developed, according to the Chinese code for seismic design of buildings [9]. Considering the lack of seismic performance, the buckling restrained brace (BRB) is adopted for seismic retrofitting, and various configurations of buckling restrained support are considered for reinforcement. The elastic response spectrum analysis (RSA) and direct integration nonlinear time history analyses (NL-TH) are carried out for the frame structure before and after reinforcement using ETABS finite element software. From the joints displacement, inter-story displacement, inter-story shear force, acceleration, energy dissipation, and other aspects of the seismic response of the strengthened structure and the non-strengthened structure, the comparison has been made. The effect of buckling restrained support and common support on the existing building structure is verified through analytical modeling. After reinforcement, there is a 40%, 39.3%, 40%, 36.4%, and 38.3% reduction in the first period of vibration after the building is strengthened by inverted BRB, V BRB, two-story BRB, single BRB, and ordinary steel braces, respectively. Strengthening of the structure by buckling restrained braces and ordinary steel braces both decrease the original building displacement by more than 50% from the first to the fourth floor. Under severe earthquakes, the use of BRB reduced the column shear by 46.6%; similarly, the incorporation of ordinary steel braces reduced the column shear by 4.72%. It is concluded that using buckling restrained braces will increase the vertical stiffness of the structure to a very high extent.

Design and Performance Analysis of Multi-Leaf Spring Using Glass Fiber Reinforced Plastic-Metal Matrix Composite

Car segments have an expanding rivalry in the market and it will in general create development in the current items by either succeed with another or altered propelled material items. A suspension framework is one of the most intriguing push territories on vehicle structure. This task effort is worried about the plan and investigation of mechanical portrayal of leaf springs that are in effect despite everything utilized generally in cars as suspension segments. Car makers have the due significance on enhancement for the mileage of the vehicle which thusly on a structure perspective the weight decrease is the most concerned one. There by the strength-weight proportion idea has been created and composite material is executed. The utilization of composite leaf spring rather than ordinary steel leaf spring is favored for the examination due to its high solidarity to weight proportion. It is made convincing to decrease the weight of the leaf spring without relinquishing the solidness and burden conveying limit of the spring by the usage of composite materials. The target of this task work is the plan and examination of the exhibition qualities of Glass Fiber Reinforced plastic (GFRP) with iron powder as a composite leaf spring and correlation with traditional leaf spring. The composite example is created utilizing hand layup technique. Exploratory work have been completed an all Universal Testing Machine for the composite and ordinary steel leaf spring and approved with the ANSYS investigation. The investigation results are connected so near test.

Effect of T-Shape Shoulder Fillet on the Plastic Deformation Properties of SS400 and LYS160 Steel

Shoulder fillets are widely used in the structural optimization design of metal dampers. However, the plastic deformation property of dampers affected by stress concentration, owing to different fillets, has not been explored in-depth. In this study, two typical metal damper materials with different plastic deformation, i.e., ordinary steel SS400 and low-yield-strength steel LYS160, were investigated. The strengthening effect of fillets under different loading is evaluated by comparing the mechanical properties of different fillet heights. Furthermore, the effect of the stress concentration caused by different fillet shapes, based on the failure mode of materials, is discussed. Subsequently, the fatigue degradation effect under the reciprocating shear loading is studied. Based on a series of studies on the deformation properties of fillets in different ductile materials, the basis for the structural optimization design under plastic deformation is provided.

Cistus monspeliensis extract as antioxidant and corrosion inhibitor of ordinary steel in 1 M hydrochloric acid medium

The aim of this study is the valorization of the Cistus monspeliensis plant, native to North of Morocco, as antioxidant and corrosion inhibitor. Firstly, the plant is extracted by maceration in a mixture of water/acetone solvents. Phytochemical tests are carried out on the extract obtained. The antioxidant power of Cistus monspeliensis extract is evaluated by two methods: the test of reduction of the free radical DPPH∙ (1,1-diphenyl-2-picryl hydrazyl) and that of Ferric reducing antioxidant power (FRAP). The electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization are used to study the anticorrosion effect of Cistus monspeliensis extract. The results showed that the extract, 27.6% yield, contains phenolic compounds in the form of flavonoids, hydrolysable and condensed tannins, saponins, reducing sugars and glycosides. This extract has an antioxidant capacity similar to that of ascorbic acid with an inhibition concentration of 0.077 mg/mL 0.102 mg/mL for DPPH and FRAP test, respectively. Tafel plots show that the extract is an excellent cathodic inhibitor. The maximum inhibition efficiency of 92 % was obtained with 0.25 g/L of the inhibitor at 298 k. The impedance plot is characterized by a single capacitive loop attributed to the charge transfer process. The results also showed that the inhibitor acts on the surface of the metal principally by adsorption, leading to the formation of a protective film limiting the corrosion of ordinary steel.

Investigation of the Axial Force Compensation and Deformation Control Effect of Servo Steel Struts in a Deep Foundation Pit Excavation in Soft Clay

This study presents a comparative analysis of the deformation control effect of the hydraulic servo steel struts and ordinary steel struts of a foundation pit based on the measured axial force of the steel struts, lateral wall deflection, and ground surface settlement due to pit excavation. The results indicate that ordinary steel struts installed via axial preloading exhibit a disadvantageous axial force loss with a maximum value equal to 86.7% of the axial preloading force. When compared with ordinary steel struts, the hydraulic servo steel strut exhibits a superior supporting effect. The hydraulic servo steel strut adjusts the axial force in real time based on the deformation of the retaining structure and the axial force of the struts. Thus, the ratio of maximum lateral deflection to the excavation depth of a deep foundation pit in soft soil is less than 0.3%. Concrete struts undergo unsupported exposure during the excavation process, leading to sharply increasing deformation of the retaining structure. Therefore, regarding a foundation pit with strict requirements for deformation control, the use of hydraulic servo steel struts rather than concrete struts is recommended.