Trapezoidal Frame Research Articles

Effects of using different materials at interface of trapezoidal reinforced concrete infilled frames–analytical and experimental approaches

Infilled frames are generally formed by the composite interaction between the frame and the infilled wall used for functional purposes. The composite interaction increases the in-plane lateral stiffness of the frame, which is considered an advantage. However, the interaction also alters the ductile mode of failure to the brittle mode along with the increased base shear owing to its higher stiffness compared with the bare frame. A detailed and comprehensive study of the literature revealed that many of research works have been done on rectangular and square frames, and studies on trapezoidal infilled frames are scarce. In this article, we studied different configurations of reinforced concrete frame structures known as trapezoidal frames, which have higher stiffness than rectangular frames. A trapezoidal frame is used for industrial buildings, and its behavior under a lateral load has already been established for a bare frame. However, the interaction and behavior of the infilled frame were investigated in this research. The behavior of a trapezoidal single-story frame was examined under both lateral loading and various interface materials. One of the most frequently suggested methods for infilled-frame analysis is the equivalent diagonal strut. Effective strut width design recommendations are available for rectangular and square frames but not for trapezoidal frames for macro modeling. Hence, to make the design easier, an effective diagonal width was developed for different interface materials with respect to the relative stiffness of various frame cross-sections, and further validation was conducted with a framework of ideology from biomimicry using the nature of a one-sixth scale model. The effective strut width for the trapezoidal infilled frame varied between d/8 and d/9 for the cement mortar and cork interfaces, where d is the diagonal length of the frame.

INFLUENCE OF DIFFERENT INTERFACE MATERIALS AND OPENINGS IN INFILL OF REINFORCED CONCRETE INFILLED FRAMES

This study analytically investigates the behaviour of trapezoidal infilled frames (TIFs) with brick masonry infills having openings and various interface materials between the brick panel and reinforced concrete frame. Single-storey single-bay frame specimens are analysed under in-plane static loading. For this investigation, the optimum angle of the column inclination for the trapezoidal frame must be determined in terms of maximum lateral stiffness. The optimum angle must be further analysed and compared with rectangular bare and infilled frames, with various materials of the interface. This infilled frame is extended to analyse the openings in the infill further. To study the effects of openings in infilled panels, TIFs with different sizes and positions of window openings are analysed and compared with the rectangular frame. This study further analyses three different combinations of interfaces and determines the intermediate stiffness of the frame combination. The main focus of this investigation is to reduce the high rigidity of the TIF leading to high base shear. It is found that, the infilled frame is stiffer than the bare frame, and the cement mortar interface is stiffer than the lead–cork interface. This research uses ABAQUS software, a finite element analysis program, for expanding the observational analysis.

Quasi-static and sound insulation performance of a multifunctional cylindrical cellular shell with bidirectional negative-stiffness metamaterial cores

This paper presents a novel type of cylindrical cellular shell with bidirectional negative stiffness (NS) metamaterial cores. The unit cell is composed of a trapezoidal frame and four cosine-shaped curved walls, therefore showing NS effect in both the circumferential and radial directions. Numerical analyses are conducted to investigate the mechanical properties, including the quasi-static behavior under radial compression and the sound transmission loss (STL) performance under an outward radiation wave within a wide frequency range. The acoustic performance is compared with those of cylindrical shells with annular hexagonal and re-entrant honeycomb cores. The NS-core and honeycomb-core cylindrical cellular shells are with the same outline dimensions and overall weight. Parametric studies of the STL on the thicknesses of the curved cell walls and the weight of mass inclusions are performed, followed by optimizations with the purpose of maximal averaged STL in two specified frequency ranges. It was found that the NS-core cylindrical shell yielded much higher STL than those honeycomb-core cylindrical shells for frequencies larger than about 200 Hz. Furthermore, the averaged STLs of the optimized designs increased by 123.7% and 39.5% for the two ranges, respectively. The results indicate that the proposed shell is not only able to endure large strain due to elastic instability, but also isolates sound waves under the very small sound-induced deformation. This design provides an alternative to the conventional core types in cellular structures by showing abundant designability and desirable structural and vibro-acoustic characteristics.

Stability Optimization of Trapezoidal Frame with Rigid Members and Flexible Joints

Stability has been an important subject in the design of a portal frame structure. Conventional stability analysis of the portal frame is normally conducted assuming that all the joints are rigid. However, the joints of a portal frame in real applications are not always rigid and semirigid connections often exist. AISC design code requires that the effect of the joint flexibility on the behavior and buckling capacity of the portal frame should be taken into account in the analysis and design procedures. To address this issue, a portal frame with flexible joints and rigid members was theoretically analyzed in the literature and closed form solution was derived for its global buckling load. However, when more parameters are involved, e.g., different leg lengths, asymmetric frame shape, and moving load, the solution to the governing equation of the stability of the frame becomes impossible. This paper presents a comprehensive parametric study on the stability of an asymmetric portal frame with flexible joints and rigid members through finite element (FE) analysis. The FE model was first validated by the existing theoretical solution in the literature. Parameters including the position of the moving load, the lengths of the two frame legs, and the span of the frame were analyzed. Design curves were developed based on the parametric study, from which the stable, unstable, and catastrophically unstable states of the portal frame were characterized. This paper contributes benchmark results for the stability optimization in the design of the portable frame of a general shape.

Research on Safety Evaluation of Quayside Container Crane Metal Structure Based on 04-FCE

In order to ensure the safety of quayside container crane in service and improve the port safety management level, from the engineering practice, according to the composition of the quayside container crane metal structure of six parts: the front girders, the rear girders, the beams, the trapezoidal frame, the tie rods, the columns, the factors that potentially have influence on the safety of the metal structure are researched, and the safety evaluation index system is built. The dimensionless algorithm of evaluation index is optimized emphatically. For the first time, the “0-4” evaluation method is used to calculate the weight value in the evaluation algorithm, and the 04-FCE evaluation method which combine the “0-4” scoring method and fuzzy comprehensive evaluation is proposed. The safety level and evaluation conclusion of the quayside container crane metal structure are determined, the suggestions for reducing the risk are given, and the rationality analysis is carried out through an example at last.

Panoramic visual tracking based on adaptive mechanism

Panoramic visual tracking has high application value in many situations, but its visual distortion is likely to cause low tracking robustness or loss of target. This paper presents a panoramic visual tracking method based on adaptive feature fusion method, the size of the trapezoidal frame is calibrated with target moving in the method, and the linear model of trapezoidal frame parameters is fitted, then according to the model trapezoidal area of target extracted, and are modified to target trapezoidal region through the affine transformation; Based on filter tracking framework, the fusion of color and shape information is as the main characteristics of the target tracking, and Bayesian fusion recursive formula is used for calculating the particle weights. The experimental results show that the proposed algorithm is better than the existing methods in tracking precision and anti occlusion, and effectively improves the robustness of panoramic visual tracking.

Optimisation design of pine backrest chair based on Taguchi method

In this paper, the ANSYS finite element analysis is applied to the pine backrest chair models. During the structure design progress, the Taguchi method for the robust design is applied. By means of the signal-noise ratio (SNR) factor effect analysis, the optimal design scheme of the structural quality of pine backrest chair is determined that the backrest chair is designed as trapezoidal seat frame, upper waling, bottom waling with II type and leaning back rear leg. Based on the above condition, the maximum equivalent stress is improved by 9.05% than the initial one, the maximum deformation is ameliorated by 14.42% and the SNR is significantly improved. When robust design is on the basic of Taguchi method, the robustness of structure quality characteristics can be enhanced. At the same time, the overall strength and stiffness of the furniture structure can be improved and the design cost can be reduced.

Torque Measurement Device Using an Integrated Microdisplacement Sensor

In this paper, we propose a torque measurement device embedded in robot arms. The device uses an integrated microdisplacement sensor and trapezoidal frame. The sensor tip of 3 mm area and 0.7 mm thickness measures the mirror tilt angle on the underside of the frame caused by a torque applied to the frame. We have successfully measured a linear output change for the torque and found that the gradient of the output change differed largely from the material and the corner angle of the frame.

Optimum trapezoidal frame with rigid members and flexible joints

A loaded trapezoidal frame with rigid members and flexible joints is studied. An exact solution method is used to find buckling and non-linear post buckling characteristics. In most cases a snap through phenomenon occurs. There exists an optimum trapezoidal shape for stability.

Partial Casting Method on Water Surface and Preparation of Multi-Channel Saw Chemical Sensor

Surface acoustic wave (SAW) devices can be used as vapor phase chemical sensors. If we make use of SAW devices with high frequency properties and multi-channel structures, highly sensitive and multi gas sensors can be realized. However, it is generally difficult to deposit different gas sensitive films on the propagation paths of monolithic multi-channel SAW devices. This paper describes the new coating method by which several types of gas-sensitive molecular films can be coated on the paths. The method is called partial casting method on water surface. It makes use of the water surface segmented by a trapezoidal frame, and the molecular film spread in the frame is compressed by the vertical movement of the frame and deposited on the substrate placed on the frame top. Several bilayers of dialkyl polyion complex and dimyristoyl phosphatidyl ethanolamine were coated on 36°Y-X LiTaO 3 SAW delay line oscillators, and odor sensor characteristics were successfully measured. It was confirmed from the present experiments that the method can be applicable to fabrication of multi-channel SAW chemical sensors with various kinds of molecular films.

Shape analysis and stereopsis for human depth perception

The perceived relative depth of two isolated short parallel lines in the center of a scene is known to depend on the disparities and positions of other items in the scene, as well as on their own disparities. We demonstrate here that the shapes of these other items also contribute significantly to the perceived depth, and that these non-disparity influences on depth judgements may already be evident when only three dots are presented as stimuli. When two short vertical test lines are surrounded by a trapezoidal “picture frame”, the perceived relative depth of the test lines is affected by the shape of the trapezoid as well as by the disparities assigned to its vertical parallel sides. The influence of the trapezoidal frame can be interpreted as an effect of perspective. The induced relative depth of the test lines is measured by recording the amount of “compensating disparity” that must be given to one of the lines in order for observers to judge the two test lines to be equidistant from the observer's viewing position. Surprisingly, for fixed disparities of the vertical edges of the surrounding picture frame, the induced depth of the test lines increases as the difference in the lengths of the vertical sides increases, regardless of whether the perspective interpretation of the difference in the lengths is consistent with or in conflict with the disparity-defined slant. Shape-related apparent depth changes are especially sensitive to the shape of the trapezoid if it is nearly rectangular, and are comparable in magnitude to those resulting from changes in disparity of the surrounding frame. When a pair of short vertical parallel test lines is presented alone, without a surrounding frame or any other items in the scene, excellent relative depth discrimination is displayed by most subjects. However, if the lines are replaced by squares, trapezoids, triangles, single horizontal lines, or other figures of about the same size as the original test lines, the slant discrimination threshold for these plane figures for nai¨ve observers become poorer by a factor of 20–100. By the use of a feedback signal, observers can be trained to use only disparity cues and ignore shape effects. Some observers have difficulty ignoring the shapes of some figures, the “difficult” figures being different for each observer. After training, the relative depth thresholds for most figures approach those of the original unconnected parallel test lines.