Mechanical Behavior of a Multisegmented Tower Anchorage Structure with an Exposed Steel Anchor Box

A tower anchorage structure with an exposed steel anchor box is commonly used for cable-stayed bridges. Many researchers have conducted studies on this structure by considering a single segment. However, in practical engineering, the stress of multisegmented tower anchorage structure is not completely similar to that of single segment, and the forces between segments affect each other. Hence, in this study, the mechanical behavior of a multisegment anchorage structure with an exposed steel anchor box was investigated via finite element analysis. Furthermore, the load transfer path and stress distribution characteristics of the structure were investigated. The results indicate that the horizontal component of the cable force is borne by the side plate of the steel anchor box, the diaphragm, and the side wall of the concrete tower column, while the vertical component is transmitted by the steel anchor box and concrete tower column. Under the action of this cable force, the horizontal component of the cable force borne by the middle segment increases, while the components at the two end segments decrease. The vertical force is greater on the lower tower segments. The stress levels on the side plate and on the diaphragm of the steel anchor box in the middle section are high. Under the cable force load, the frame formed by the end plate and side plate of the steel anchor box expands outward. The end plate is mainly under a tensile load, and the tensile stress level on the lower section exceeds that on the upper section. A high-stress area for the concrete tower is observed in the steel-concrete joint. The stud group of the anchorage structure is subjected to horizontal and vertical shear forces, and no “saddle-shaped” distribution of the stud shear is found. An optimal arrangement method for the stud group was proposed to optimize its mechanical performance.

Reinforcement of steel beam-to-double column moment connection using side plates

One of the disadvantages of conventional steel structures in Iran is the common way of I-shaped beam to double column fixed connection that do not perform well against seismic loads. This article uses the side plate to modify and optimize the connection. Using this new geometry, the beam-to-column direct connection is eliminated, and there is no longer any concern about the brittle fracture of penetration weld of the beam-to-column connection and the weakness of panel zone that occur in the common fixed connections. In addition, by eliminating the direct transfer of beam flange force to the double column connection plate, the problem of deformation, complexity or buckling of the cover plate of the column is spontaneously removed. In this paper, in order to investigate the nonlinear behavior of beam-to-double column connection system, a number of three-dimensional finite element models under the effect of cyclic loading have been analyzed. The results show that the beam-to-double column connection using the side plates has good strength and ductility and can be used in special moment frames for seismic areas.

STRESS RESPONSE AND INITIAL STIFFNESS OF SIDE PLATE CONNECTIONS TO WCFT COLUMNS

To study the mechanism of load transfer in double-side-plate connections between I-beams and wall-type concrete-filled steel tubular columns, a pseudo-static experiment and finite element analysis were conducted for two full-scaled specimens. The results revealed that the primary load was transmitted along an S-shaped path in the side plate, and the primary strain occurred in an X-shaped region between the left and right steel beam flanges. The shear force in the steel beam web was transmitted first to the side plate centre and then to the joint area, where the side plate, steel tube web, and concrete all resisted the internal force. Based on principal component methods, a calculation formula was established for initial rotational stiffness that comprehensively considers the influence of the tensions, compression, and shear deformation of the cover plate, side plate, and web. Comparing this formula with an existing model showed that the proposed formula is suitable for new types of side plate joints. Moreover, it can accurately calculate the initial rotational stiffness of the joint, thus providing a reliable basis for future engineering design.

Steady-State Flow Characteristics and End Clearance Optimization of Internal Gear Grease Pump

The internal gear grease pump is a mechanical device used for transfer of high viscosity fluid. The existing clearance between the end faces of the internal or external gear and the floating side plate might cause pump leakage during operation. In order to obtain the optimal end clearance of the internal gear grease pump, the rheological features of the lubricating lithium-based grease for various temperatures are explored via rotating rheometer. Shear force and apparent viscosity are chosen as monitored experimental parameters. The experimental data is fitted to obtain grease rheological features at various temperatures. The end clearance flow field model and the leakage model are established. Fluent software is employed for solving the flow field model and exploring the effect of temperature, end clearance, and speed on grease leakage. Superior grease flow performance is observed with an increase in temperature, which makes it to easier for the grease to leak from the end clearance. With an increase in the end clearance and the working pressure of the pump, an increase in leakage is also observed. Furthermore, it is found that rotational speed also affects the pump leakage. The leakage mechanism is obtained by combining the rheological features of the grease at the end clearance. The mathematical model method is utilized to solve for the optimal value of the end clearance.

Offset Detection of Grate Trolley’s Side Plate Based on YOLOv4

Side plate offset is one of the grate system faults. If it is not dealt with in time, some accidents will occur and economic losses will be made. Aiming at the problems like time-consuming, labour-wasting, and low intelligent by the side plate offset detection method manually, an autoside plate offset detection method is proposed, based on You Only Look Once version 4 (YOLOv4). Two cameras were fixed to collect the image information of the grate trolley’s side plate. With reference to the grate trolley’s operation, the offset judgment rules were set. YOLOv4 object detection algorithm was used to detect the side plate and trolley’s chassis frame in video frame images. A baseline was set according to the position information of the trolley’s chassis frame output by detection, and then, the position intervals between side plates and the baseline could be determined by calculation. According to the judgment rules, the scheme in this paper could detect the offset fault of the trolley’s side plate timely, and an alarm would be made automatically when faults are detected. Our video images of the trolley’s side plate were collected and sorted in Baogang Group sintering plant for testing. In this experiment, no error judgment was made, and the average detection and judgment time was 0.024 s. In this paper, rather than manually, the real-time automatic detection was realized to detect the offset fault of the trolley’s side plate so as to provide a new solution for offset detection of the grate trolley’s side plate.