Force Transmission Path Research Articles

A Novel Wedge Anchor System for Double-Layer CFRP Plate Cables: Concept, Theoretical Analysis and FEA.

This study introduces an innovative wedge anchor for double-layer carbon fiber reinforced polymer (CFRP) plate cable to address the current limitation of traditional wedge anchors. By employing the design concept of "secondary force transmission path", the friction force for anchoring the CFRP plate is effectively transferred into the barrel through its contracting wedge, thus reducing the clamping pressure requirement of traditional wedge anchorage for anchoring thick or double-layer CFRP plates. Based on this conception, this study presents a theoretical analysis model for predicting the influence of parameter variations on the compressive stress of the CFRP plate, which can serve as a tool for rapid configuration preliminary design. Through finite element analysis, the internal stress distribution of the anchor is thoroughly investigated, and the theoretical analysis model for fast predicting compressive stress of CFRP plate is also validated. The results also indicate that the anchorage conception is valid and effective, providing sufficient anchorage of CFPR plates with an anchorage length of 100 mm.

Multi-objective topology optimization simulation study based on motor

Abstract OptiStruct software is applied for structural optimization of the motor structure to solve the problem of resonance in a specific operating frequency range and reduce the motor operating noise. Comparing the experimental and simulated modal frequencies, a modified multi-objective topology optimization model is proposed to ensure the validity of the model, and a new optimization function is constructed to optimize the multi-objective topology of the motor housing. The results show that the geometric reconfiguration of the motor housing concerning the optimized model force transmission path achieves the effectiveness of reducing resonance noise. The multi-objective topology optimization model provides a feasible way to solve the motor-specific frequency resonance and operation noise problems.

Research on Lightweight Rail Vehicle Body Based on Sensitivity Analysis

In view of the development trend of rail vehicles towards higher operating speed and low power consumption, a scheme for a lightweight rail vehicle body is proposed, based on sensitivity analysis. Using topology optimization of the vehicle body section structure, finite element models of the vehicle body section structure under single working conditions and multiple working conditions were established, respectively, and the force transmission path of the vehicle body structure under different working conditions was obtained under different working conditions. The topology of the cross-sectional structure of the vehicle body was optimized by the compromise planning method with weights. Then, a reconstruction and performance analysis of the car body section was carried out based on the optimization results and finally the finite difference method was used to analyze the sensitivity of the vehicle body structure and the vehicle body size was optimized based on the sensitivity analysis results. The results showed that the weight reduction rate of the railway vehicle body section stiffened plate was 4.47% compared to the optimization period and the modal performance analysis results of the optimized structure met the requirements. The weight reduction ratio of the optimized body structure was 21.6%

Mechanical Performance Investigation of a Flat-Roof and Four-Slope Folded Plate Structure

The flat-roof and four-slope folded plate structure is a space thin-walled structure composed of four trapezoidal plates and a rectangular plate parallel to the bottom surface, which is widely used in various engineering applications. In order to clarify the force transmission path and stress distribution law under the action of this structural load, the folded plate structures were made by utilizing the plexiglass with the thicknesses of 3 and 4 mm, respectively, and had the simple support on opposite sides and fixed support on another opposite side. Then, the static load tests and ANSYS finite element analysis were implemented, and the results were compared. It shows that the test results are basically consistent with the finite element calculation results, the maximum stress values of the folded plate structure along the X and Y directions appear in the same position, and the maximum stress value of a 3 mm thick folded plate structure is greater than that of 4 mm. The junction position of the roof and the slope plate is the dangerous section, and the special treatment should be made for this section to prevent the damage of folded plate structure in the practical engineering. Moreover, some reasonable measures also should be taken to meet the design requirements of the plate–plate junction position.

Optimization of the Mechanical Properties of Bolted Connections between Concrete-Filled Tubular Columns and Steel Beam with Reinforcing Rings

To study the mechanical performance of bolted connections with different structural forms of reinforced rings, based on the results of monotonic loading tests on two bolted connections between a concrete-filled steel tubular column and a steel beam with an outer reinforcing ring, this article uses ABAQUS v.2020 software to establish a three-dimensional refined finite element analysis model of such connections using appropriate constitutive models for concrete and steel. Subsequently, the effect of the dimensions of the steel beam, reinforcing ring, and cover plate on the load-bearing properties and the failure mechanism of the connections is investigated, and the numerical model is consistent with the verification test results. Then, the numerical simulations comparing bolted exterior reinforced rings under seven different construction measures (i.e., number of bolts, stiffeners) based on a conventional welded exterior reinforced rings with rigid connections (i.e., CGJ) are standardized. The research results indicate that when four rows of bolts are introduced on exterior reinforced rings, the web of steel beam is welded with stiffeners, and the top and bottom reinforced rings are also added with stiffeners; this bolted connection with an external reinforcing ring (i.e., GZ-7) can achieve the rigidity and load-bearing capacity of a fully welded external reinforcing ring rigid connection. At the same time, the reinforcing ring plate is bolted to the flange of the steel beam, and the force transmission path at the connection is changed to avoid the brittle fracture easily caused by the welded flange joints. It is also in line with the development trend of sustainable construction of “assembly” and “disassembly”.

Intelligent design and buckling experiment of curvilinearly stiffened thin-walled structures

Curvilinearly stiffened variable-stiffness structures offer excellent load-bearing capacities and design flexibility, particularly for thin-walled structures with cutouts. Nevertheless, the complex combination of numerous variables, buckling failure modes, and unclear load-carrying mechanisms present significant challenges to structural analysis and optimization. Hence, a unified characterization method for nonuniform layouts and variable thicknesses is proposed and an intelligent optimization framework based on structural image learning is established. Buckling experiments on two stiffened panels and a corresponding numerical analysis are performed to verify the effectiveness of the method under axial compressive loading. Results show that the curvilinearly stiffened panel exhibits a superior load-bearing capacity of 28.8% compared with an orthogonally stiffened panel. Specifically, the curvilinearly stiffened panel efficiently transfers axial loads to a broader region and avoids interruptions in the force transmission path by cutouts, thereby resulting in material and buckling failures simultaneously.

The force at the implant cannot be assessed by the mallet force-Unless supported by a model.

The implantation of uncemented prostheses requires the application of sufficient forces to achieve a press-fit of the implant in the bone. Excessive forces have to be omitted to limit bone damage. Force measurements along the force transmission path between mallet and implant are frequently used to investigate this trade-off. Placing a load cell at a position of interest (PoI), which might be the implant bone interface or the head taper junction, is technically challenging or even impossible so that nearby positions are chosen. Thus, a certain inertia and stiffness remain between the PoI and the sensor, and consequently the measured dynamic forces differ from those at the PoI. This experimental and numerical study aimed to investigate the amount of force reduction along the transmission path while joining femoral heads to stem tapers. Forces were measured in vitro at the tip of the mallet, directly above the polymer tip of the impactor and below the stem taper. Springs and masses were used to represent the responding tissue of a patient. A semi-empirical numerical model of the force transmission path was developed and validated in order to simulate a larger range of responding tissue properties than experimentally possible and to investigate the influence of different surgical instruments. A distinct attenuation was observed since the peak forces at the impactor reached 35% of the applied peak forces and 21% at the stem taper, respectively. The force curves were replicated with a median root mean square error of 3.8% of the corresponding mallet blow for the impactor and 3.6% for the stem. The force measurement position and the used surgical instruments have a strong influence on the measured forces. Consequently, the exact measurement conditions with regard to sensor positioning and used surgical instruments have to be specified and hence only studies with similar setups should be compared to avoid misestimation of the forces at the PoI. The proposed dynamic numerical model is a useful tool to calculate the impact of the chosen or changed mechanical parameters prior to executing experiments and also to extrapolate the effect of changing the applied forces to the resulting forces at the PoI.

Simulation Analysis and Lightweight Design of Automotive Transmission Shafts Based on Optistruct

The transmission shaft is an important power transmission assembly in the automotive transmission system. Its structural mechanical performance is crucial for the comfort and safety of the vehicle. For this purpose, the transmission shaft of commercial vehicles is taken as the research object. Mechanical simulation analysis is conducted based on the finite element analysis software of Optistruct to investigate the stress and displacement distribution of various components on the transmission shaft under maximum torque and to verify its strength and stiffness. In addition, based on the stress distribution and manufacturing process requirements of the transmission shaft, a lightweight design is carried out for the transmission shaft components. The research results indicate that using simulation analysis methods can quickly obtain the force transmission path of the transmission shaft assembly and introducing manufacturing process requirements for lightweight design not only meets the manufacturing requirements but also has a more uniform stress distribution. The overall structure of the transmission shaft has been reduced from 23.8 kg to 16.8 kg with a weight reduction of 30%. The lightweight design method described in this article can quickly achieve weight reduction goals while meeting the structural strength of the transmission shaft.

Cyclic test evaluation of double skin composite hybrid coupled wall with frictional steel truss coupling beams

The seismic performance of double skin composite shear walls (DSCSWs) has significant superior to conventional reinforce concrete (RC) shear walls. Previous studies have neglected the changes of axial compressive forces and bending moments actting on the top of wall piers. In addition, behaviors hybrid coupled wall (HCW) under real boundary condition have not been fully investigated. Thus, in this study, a novel quasi-static test which incorporates the boundary conditions of substructures in a prototype building was preformed. And a cyclic test was carried out on a 2/3-scaled double skin composite (DSC) HCW with frictional steel truss coupling beams (FSTCBs) using the proposed method. The seismic behavior of specimen under reversed lateral cyclic loads was investigated. The failure modes of the wall piers mainly included local buckling of the steel faceplate, fracture of the side plate, and concrete crushing at the corners of walls. The force-displacement hysteresis curve of FSTCBs was obtainable from the attached instruments as the force transmission path of the steel truss could be clearly observed. DSCSW pier deformation was evaluated based on the deformative relationship between the wall pier and FSTCB. The FSTCB primarily dissipated 80% of the total energy input prior to damage occurring in the DSCSW. Strain distribution curves along the DSCSW showed that the pre-peak-resistance plane section assumption was still valid.

Ultimate strength of CFST-gusset plate joints with ring stiffener plates under tension

Tube-gusset plate joints are increasingly adopted in large lattice towers for wind power, due to the advantages of simple fabrication and clear force transmission path. To investigate the mechanical performance of CFST-gusset plate joints with ring stiffener plates, tensile bearing capacity tests of three tube-gusset plate joints were performed in this study. The test results showed that setting ring stiffener plates and filling concrete could effectively improve the stiffness and tensile bearing capacity of tube-gusset plate joints. In addition, the finite element (FE) models were established in this study, and the accuracy of the FE models was verified by comparing it with the test results. Parameter analysis showed that the increase of the width ratio (R/D) and thickness ratio (tr/t) of the ring stiffener plate and the width ratio (LGP/D) of the gusset plate was a significant method to improve the ultimate strength of tube-gusset plate joints under tension. But when the width ratio and thickness ratio of ring stiffener plates exceeded the limit relationship, the ultimate strength of joints would not be further improved, which was easy to cause waste of materials. Finally, to simplify the calculation of CFST-gusset plate joints with the ring stiffener plates, an equivalent interaction method (EIM) was proposed in this study, which could accurately predict the ultimate strength of CFST-gusset plate joints with ring stiffener plates under tension.

Experimental study on the influences of structural characteristics and vertical load on the seismic performance of zhutou puzuo

Investigating the seismic performance of puzuo is critical for protecting the Yingxian Wooden Pagoda. In this study, the influence of different structural characteristics and vertical loads on the seismic performance of Zhutou Puzuos was investigated. The Zhutou Puzuos in the outer circles on the second to fifth open floors were tested under cyclic loading. The test results indicated that the dominating deformation of the Zhutou Puzuo was rotational in the positive direction, whereas both rotational and slip deformations contributed to the deformation in the negative direction. The energy-dissipation and load-bearing capacities increased with an increase in the number of pu, which is a typical structural characteristic. The position of the initial slip varied as the vertical load increased during the early stage of the test. The increasing ratios of the negative bearing capacities of the puzuo joints on the second, third, fourth, and fifth open floors were 2.89, 3.93, 5.39, and 1.17, respectively, as the vertical load increased by 3.7 times. Additionally, the force transmission path of the vertical load included the nidaogong and huagong orientation with the majority of the loads transmitted by nidaogong orientations. This study provides valuable experimental data and analysis methods for investigating the seismic performance of the Yingxian Wooden Pagoda.

Progressive failure and seismic fragility analysis for transmission towers considering buckling effect

Transmission towers are essential components supporting the operation of the power grid. Accurately predicting their ultimate bearing capacity and progressive failure improve the performance design of electrical power systems. This paper proposes a progressive failure method for transmission towers considering the buckling and post-buckling behaviors of steel angles. To simulate the nonlinear hysteretic behaviors of steel angles, a phenomenological hysteretic model (PHM) is introduced and embed into the ABAQUS software by calling a user-defined subroutine VUMAT. The accuracy and reliability of the PHM are verified through a full-scale test of a transmission tower. The comparison results demonstrate that the PHM can accurately reproduce the displacement and strain responses of the transmission tower and the ultimate bearing capacity, with a maximum error of <15%. The buckling failure of leg members is the main factor for the collapse of the transmission tower. The study also investigates the progressive failure process of the transmission tower under strong earthquakes and estimates the collapse fragility and seismic losses. The results reveal that early failures of steel angles may alter the local force transmission path of the tower and eventually lead to its collapse. This research provides suggestions for the structural optimization and design decision-making of transmission towers.

Construction of strut‐and‐tie models for members under complex stress states based on topology optimization

AbstractThe construction of strut‐and‐tie models (STMs) is the key, but also the difficulty when the model is used to describe the force mechanism and guide the reinforcement layout design of concrete disturbed regions (D‐regions). Topology optimization is a promising way to guide STMs construction. Different from the existing construction methods of predetermining nodes, the angle of inclination of the truss elements is first determined to ensure that it is consistent with that of the principal stresses in a 2D finite element model of the structure. The constructed model can well reflect the force transmission path of structural members, and it is better than the existing methods when it is evaluated through the principle of minimum strain energy. To verify the validity of the STM, a reinforcement layout scheme is adopted completely according to the position of the tension ties. On this basis, another reinforcement layout scheme adds additional transverse reinforcements in the bottle‐shaped stress field. The nonlinear finite element comparative analysis of an irregular deep beam designed by the two schemes is carried out. The results show that the two ultimate loads are close. Brittle failure occurs in the former, while the latter has higher deformability and eventually ductile failure occurs.

An analytical method for assessing the live load deformation of a suspension bridge with an improved central buckle

Suspension bridges lack favorable supports for global vertical stiffness, making it challenging to meet the road safety requirement due to the excessive deflection of stiffening girder when developing towards larger spans. It hinders the development of the ultimate span of suspension bridges and reduces the utilization rate of materials. This paper proposes an improved central buckle (ICB) to increase the global vertical stiffness of suspension bridges. Without changing the constraints of the stiffening girder, the central buckle and horizontal cable are placed at the mid-span and bottom of the stiffening girder, respectively, which combination is referred to as ICB. It restrains the horizontal displacement of the main cable and reduces the maximum deflection of the suspension bridge due to the asymmetric live loads. The analytical expressions of the deflection and girder-end rotation of the suspension bridge with the ICB are derived based on the deflection theory. The expression of the variable equivalent horizontal spring stiffness of the ICB is proposed and verified by a finite element model of the suspension bridge. These results prove that the ICB can effectively restrain the horizontal displacement of the main cable caused by the asymmetric live load and significantly reduce the vertical deflection of the stiffening girder. The performed parametric analysis clarified the mechanism of increasing the vertical stiffness of the suspension bridge based on the ICB force transmission path, providing a new design scheme for improving the global vertical stiffness of the suspension bridge and expanding its upper span limit.

Preliminary Design of a Steel–UHPFRC Composite Truss Arch Bridge and Model Tests of K-Joints

The preliminary design and comparisons of major technical and economic indicators between a steel-ultrahigh-performance fiber-reinforced concrete (UHPFRC) composite truss (SUCT) arch bridge and a concrete-filled steel tubular (CFST) arch bridge with both spans of 375 m are carried out in this study. Compared with the CFST arch bridge, the SUCT arch bridge can improve the durability of the bridge and has advantages in terms of steel consumption, self-weight, carbon emission, and other indicators due to the use of UHPFRC with high compressive strength as the arch ribs to bear the large axial forces. Adoption of the cyclic construction method for the SUCT arch bridge with two closure processes results in a total cost basically equivalent to that of the CFST arch bridge. For the K-joints in the connection area of the UHPFRC arch ribs and steel web members, a new hybrid connection form of “perforated shear connectors (PBL) + headed studs” is proposed. Loading tests in three directions in plane, pull-out tests, and parameter analysis are carried out. The experimental results show that the new hybrid connector is reasonable for the K-joints, which has advantages of large stiffness, short force transmission path, and high efficiency, and can ensure the continuity of steel fibers. Moreover, the new hybrid connector displays good shear performance, pull-out performance, and high bearing capacity. Based on the results of parameter analysis, the sensitivity of the pull-out bearing capacity to the three variables is compressive stress in the arch rib, followed by the tensile and compressive strengths of UHPFRC.

Refined Modeling Method and Analysis of an Electromagnetic Direct-Drive Hydrostatic Actuation System

The hydrostatic actuation system based on linear actuators improves the complex piston force and long transmission path of the traditional electro-hydrostatic actuator (EHA). However, new nonlinear factors in the linear actuator and direct-driven piston are introduced into the system, which present challenges to system modeling and control. To improve the accuracy of system performance prediction, this paper analyzed the working characteristics of an electromagnetic direct-drive hydrostatic actuation system (EDHAS). A dynamic model of the electromagnetic linear actuator including the LuGre friction model was established. The high-pressure internal leakage of the direct-drive pump was described by an inclined eccentric leakage model. The Karnopp friction model was applied to solve the problem of switching between viscous and sliding friction in a cylinder. The hydraulic components model was established based on AMESim, and the electromagnetic linear actuator model and the system controller model were established in Matlab/Simulink, to establish a refined electromechanical–hydraulic co-simulation model of the EDHAS with electromagnetic, mechanical, hydraulic, and control coupling. A system performance test platform was built. The simulation results of the direct-drive piston displacement, the system pressure, the system flow rate, and the cylinder displacement match well with experimental results, which verifies the validity and accuracy of the refined modeling method.

Research on bearing capacity of honeycomb plate box-type hollow roof structure

• A new type of honeycomb plate box-type hollow roof structure is prepared with good ductility. • The validity of the numerical analysis model was verified by comparing the results of experiment with the results of the coupling model. • Influential factors on the bearing capacity of honeycomb plate box-type hollow roof structure obtained by parametric analysis. In this paper, a new type of honeycomb plate box-type hollow roof structure was prepared. The failure modes and mechanical properties of the box-type hollow roof structure were analyzed by bearing capacity test and numerical simulation. The validity of the numerical analysis model was verified by comparing the results of experiment with the results of the coupling model. The influence of specification of honeycomb plate, height of the side plate, rise-span ratio of the structure, configuration of box-type hollow roof structure, and initial geometric defect on the bearing capacity of the honeycomb plate box-type hollow roof structure were analyzed. The results show that the failure mode of the specimen is tensile failure of the surface plane of the honeycomb plate with strengthened frame and buckling instability of the plate near the joint. The results of coupling model are in good agreement with the results of experiment. The stiffness of honeycomb plate box-type hollow roof structure can be improved by the thickness of plate and the height of core layer of honeycomb plate. The ultimate bearing capacity of the honeycomb plate box-type hollow roof structure increases with the increase of the height and rise-span ratio. The bottom plate of box-type hollow roof structure can make the force transmission path of the structure more reasonable and effectively reduce the phenomenon of stress concentration. Compared with the structure without initial geometric defect, the stable bearing capacity of the structure is reduced by 18.6 % and the ultimate bearing capacity is reduced by 28 % when the initial geometric defect of 80 mm is applied to the structure.

Seismic performance of glulam timber post and beam structures with and without light frame timber shear wall infill

Timber post and beam structure is typical frame construction with a simple structural system and clear force transmission path. This work studies the seismic performance of glued-laminated timber (glulam) post and beam structures under cyclic loading, as well as the effect of light frame timber shear walls on their seismic performance. Experimental investigation on two types of full-scale glulam post and beam structures was carried out to compare the failure modes, mechanical properties, and energy dissipation. According to the test results, simplified models whose nonlinearity was assumed to be concentrated plasticity in the springs were developed. The comparison between test data and model prediction has a good agreement in terms of evaluation from backbone curves and strength degradation ratio. This calibrated model was then adopted as a benchmark model for further parametric analysis. Eight different configurations considering various aspect ratios were modeled to assess the influence of elastic stiffness and the maximum load-carrying capacity using the pushover analysis. The test investigation and numerical analysis of the glulam post and beam structures with and without light frame timber shear walls help comprehensively understand the seismic performance, providing some valuable guidance for further studies and structural design in engineering practice.

Experimental and numerical investigation on the anti-progressive collapse performance of fabricated connection with CFST column and composite beam

The column-to-beam connection is of critical importance in the resistance of structures to progressive collapse. In previous progressive collapse tests, the concrete-filled steel tubular (CFST) column-to-composite beam connection with the ring plate experienced a high resistance and clear force transmission path. However, the ring plate and composite beam were assembled onsite. It is necessary, therefore, to further study the CFST column-to-composite beam fabricated connection. In this paper, an experimental and numerical study was carried out on the anti-progressive collapse performance of the fabricated connection with CFST column and composite beam. Three types of fabricated connections and two types of shear connectors were compared to investigate the failure mode, vertical resistance-deformation mechanism, and strain-deformation relationship. The bending moment and axial force of the steel beam as well as the contribution ratio of each component to vertical resistance were calculated and analyzed. Moreover, the nonlinear parameters of progressive collapse resistance of the specimens were compared with DoD and FEMA350 criteria. Finally, the dynamic increasing factors (DIFs) by the test, finite element (FE) model, and energy balanced (EB) method were discussed.

Experimental Study and In-depth Tensile Mechanism Analysis of Grouted Sleeve Lapping Conectors

To study the failure modes, bearing capacity, ductility, and sleeve strain of grouted sleeve lapping connectors, 36 specimens were tested under uniaxial tensile load. The test results show that the sleeves are under longitudinal tension at the beginning, which changes to longitudinal compression in the late stage of loading, and the changing load increases gradually with the lap length. The force transmission path and mechanical mechanism of the connectors are analyzed. The distribution and development process of longitudinal sleeve stress is analyzed based on the constitutive model stress, and it is found that the sleeve changes from longitudinal tension to longitudinal compression at the late loading stage, which is consistent with the test results. Based on the test, the calculation formulas of the ultimate bond strength and critical lap length of the grouted sleeve lapping connector are proposed. The research results lay a theoretical foundation for the application of grouted sleeve lapping connectors.