Lateral Deflection Research Articles

Experimental and analytical investigation on eccentric performance of circular CFST columns jacketed by concrete-filled square tube

This paper presents an experimental and analytical investigation of the eccentric behaviour of circular CFST columns strengthened by a square steel tube and sandwiched concrete jackets. The main parameters include the eccentricity, strength of sandwiched concrete, and thickness of the outer steel tube. The failure modes, load-axial displacement curves, load-lateral deflection curves, and longitudinal strain distributions are presented. The effects of these parameters on the ultimate strength, ductility index, and lateral deflection are discussed in detail. Based on the longitudinal strain results obtained from the experiment and basic hypotheses, the possible positions of the neutral axis in the column section at the ultimate limit state were analysed, and three failure patterns of the specimens were determined. Analytical formulas corresponding to each failure pattern were derived to calculate the eccentric load-bearing capacity of the strengthened columns based on the limit equilibrium theory. Finally, a simplified formula was proposed to serve as the basis for future designs and applications.

Assessment of purlins with paired torsion bracing in sloped roof systems: Direct strength method approach

A Direct Strength Method based methodology has been developed by the authors for the prediction of local buckling and distortional buckling strength of purlins with paired torsion bracing. In a previous study, the methodology was presented and discussed for zero slope roof systems in by the authors. In this paper, the authors reformulated the developed methodology to include the effect of slope in the structural behavior of the roof systems. Equations have been developed for the strength prediction of sloped roof systems for simple span and multi-span interior conditions (fixed support conditions at both ends). As downslope forces are introduced to the sloped roof systems, the lateral displacement of the diaphragm is affected, and the stress distributions are impacted along the purlin cross sections. Typically, with the increase in the roof slope, the lateral diaphragm deflection decreases during which the stress distributions approach the constrained bending distribution increasing the strength. When the roof slope is increased further and the lateral deflection of the purlins moves downslope, there is a considerable decrease in the predicted strength. Therefore, for steep roof slopes, a considerable inelastic reserve capacity is observed which when accounted for will improve the predicted strength. The component stiffness method is utilized in the process, considering displacement compatibility for the calculation of the anchorage forces within the purlin system. Partial restraint of the diaphragm that is provided by the sheathing is considered in the procedure. The developed methodology herein this paper incorporates the effects of first-order and approximate second-order torsion for the prediction of the actual stress distributions along purlin cross sections. This stress distribution may significantly differ from the conventionally assumed constrained bending distributions which may result in substantial differences in the predicted local buckling and distortional buckling strengths for purlin systems.

Adaptive MPC-Based Lateral Path-Tracking Control for Automatic Vehicles

Adaptive MPC-Based Lateral Path-Tracking Control for Automatic Vehicles

ANALYTICAL DEFLECTIONS AND STRESS ANALYSIS IN SLENDER BAR FRAMED STRUCTURES SUBJECTED TO ANTISYMMETRIC LATERAL LOADS

Mechanical analysis of the lateral deflections in slender structures is an interesting task to model the mechanical response to transverse forces like seismic or wind forces. Special interest is focused on buildings, communication towers, or tower cranes, as well as any other kind of framed structures. A pure analytical solution for the lateral deflections and vertical displacements, stresses and bending moments of a framed structure under power-law lateral loads is presented in a non-dimensional form. The internal forces of the structure are stated by the force method which drives to a set of linear equations, which are analytically solved, thus reaching an exact, continuous, and differentiable solution. A parametric analysis is performed on a simplified case to show the influence of the dimensionless parameters on the solution. An explicit solution for deflections and bending moments is included for one and two structural levels. The solution is validated via numerical software, using STR and ABAQUS, upon a population of ten, building-like structures. Keywords: structure, deflections, force method, tower, building, lateral load, non-dimensional, antisymmetric

Permanent Magnet Electrodynamic Suspension System Integrated With a Car: Design, Implementation, and Test

In this paper, a permanent magnet electrodynamic suspension (PMEDS) system integrated with a car has been developed by our group, along with a 100-m-long test track made of copper. The entire vehicle weighs 2.8 ton and is freely suspended in air over 35 mm without a lateral constraint on guideway. The car uses its own wheels and engine to provide a take-off speed for the PMEDS system, eliminating the excessive costs of the motor, with a maximum speed of 70 km/h. Firstly, a new topology structure equipped with the damping magnets is presented. Afterward, the onboard magnets and guideway are designed via the simulation method verified by the high-speed rotary experiment platform with a diameter of 2500 mm, clarifying the mapping between the electromagnetic forces and structure parameters. The suspension frame and gap adjustment mechanism are developed, and a complete test system is built to monitor the levitation gap, accelerations and deflection angle. Lastly, the integrated PMEDS system is implemented and tested. In-house experiment and line test results not only reveal that the PMEDS has a significant weak guidance capability, but also confirm the effectiveness of the proposed damping magnets. Through the damping magnets, the maximum lateral deflection is limited to less than 11°. The tested levitation-drag-ratio is in general agreement with the simulation results. The great suspension capacity of the PMEDS system can be visually demonstrated. This paper conducts the free suspension test of the PMEDS system for the first time in China, which can open up prospects for further engineering applications.

A nonlinear optimization method for calibration of large‐scale deep cement mixing in very soft clay deep excavation

AbstractThis work proposes a novel technique to conduct back‐analysis of lateral displacement of deep cement mixing (DCM) columns in deep excavation construction. For the first time, we propose a process to investigate both soil and underground structure end‐to‐end automatically. The novel technique is a complex combination of three crucial factors: (1) a nature‐inspired optimization algorithm (O), (2) a three‐dimensional PLAXIS Geotechnical Engineering software (P) and (3) a modern Python language programming (P), hereinafter called the a nature‐inspired optimization algorithm (O), a three‐dimensional PLAXIS Geotechnical Engineering software (P) and a modern Python language programming (P) (OPP) technique. The novel meta‐heuristic algorithm simulated the co‐evolved partnership behavior of shrimps and goby fishes, termed Shrimp and Goby Association (SGA), which plays an important role in complex analyses. A series of exams to determine the SGA's performance is conducted on 38 benchmark test functions (IEEE Congress on Evolutionary Computation 2017 and 2019) and three real‐world engineering design problems to showcase its applicability. The metaheuristic and PLAXIS 3D analysis work well together, which makes the back‐analysis technique powerfully to determinate stiffness parameters instead of the traditional approaches. Based on the optimized parameters, the lateral deflection of DCM and soil are well predicted for excavation. This study proposes a technique to estimate efficiently the stiffness parameter for very soft soil. As a consequence of the optimization process, an equation to determine the stiffness parameter of DCM columns from laboratory test is also proposed. Based on the obtained results, this research provides a comprehensive methodology for predicting risk, enhancing safety, saving time and money, and effectively designing and constructing underground structures.

Deformation Characteristics of Soft Soil Induced by Deep Excavation and Its Impact on Adjacent Tunnels: A Case Study in Shanghai

This research aims to comprehensively study the deformation characteristics of an excavation pit of 7,600 m2 (117 m long, 65 m wide and 20.8 m deep) in soft clay in Shanghai, China. The deformation characteristics of the mixing pile in both the vertical and lateral directions, ground surface movement, and surface displacement in the adjacent tunnels were comprehensively investigated. The results indicated that the maximum lateral deflection was approximately 85 mm at the end of the excavation and that the maximum lateral displacement, δhm, was in the range between 0.12%He and 0.41%He. The factor of safety of the excavation was approximately 1.6, which was larger than that of most reported sites in Shanghai. The relationship between heaving and excavation depth was strong between 0.0047%He and 0.056%He, and a relatively large settlement was observed at a distance of approximately 0.2He–0.3He. The tunnel surface of the eastbound line deformed upward and inward with a maximum horizontal convergence of 4 mm. A multilayer regression model was also validated, showing a maximum discrepancy of 26.5 mm. This research provides a valuable historical case for the documentation of the deformation characteristics of excavation pits close to existing foundation pits and tunnels.

Individualized driver amplitude in liver MR elastography: a linear regression study.

Current liver magnetic resonance elastography (MRE) scans often require adjustments to driver amplitude to produce acceptable images. This could lead to time wastage and the potential loss of an opportunity to capture a high-quality image. To construct a linear regression model of individualized driver amplitude to improve liver MRE image quality. Data from 95 liver MRE scans of 61 participants, including abdominal missing volume ratio (AMVR), breath-holding status, the distance from the passive driver on the skin surface to the liver edge (Dd-l), body mass index (BMI), and lateral deflection of the passive driver with respect to the human sagittal plane (Angle α), were continuously collected. The Spearman correlation analysis and lasso regression were conducted to screen the independent variables. Multiple linear regression equations were developed to determine the optimal amplitude prediction model. The optimal formula for linear regression models: driver amplitude (%) = -16.80 + 78.59 × AMVR - 11.12 × breath-holding (end of expiration = 1, end of inspiration = 0) + 3.16 × Dd-l + 1.94 × BMI + 0.34 × angle α, with the model passing the F test (F = 22.455, P <0.001) and R2 value of 0.558. The individualized amplitude prediction model based on AMVR, breath-holding status, Dd-l, BMI, and angle α is a valuable tool in liver MRE examination.

Coupled influences of magnetic field and several thermal loads on vibration of thermoelastic nano-ceramic (Si3N4) beam

Our study investigates the vibration of a thermoelastic nano-ceramic (Si3N4) beam exposed to a magnetic field under the effect of a moving heat source and different types of thermal loads. These nanobeams are modeled as non-Fourier heat conduction. In our formulation, the equation of motion and the principle of energy conservation from two coupled partial differential equations have been driven. A direct approach has been used to find the solutions to the governing equations using the Laplace transform definition. Numerical Laplace transform inversion was calculated using Hoing's approximation approach. Solutions have been applied to silicon nitride (Si3N4) nanobeam ceramics. Figures show the distribution of temperature increment, lateral deflection, and stress with different values of magnetic field and several thermal load parameters. In all the studied nanobeam functions, the magnetic field and several thermal loads’s parameters have significant effects. They could be used as tuners to control the vibration and temperature increment. In the present study, a moving heat source, and different thermal loads have been applied to a non-Fourier nanobeam exposed to a magnetic field. The results have been compared with those obtained in the thermoelastic cases.

Study on the mechanism and countermeasures of progressive collapse in deep excavation retained by multilayer struts

There is still a lack of research on the resilient design of excavations retained by multilayer struts against progressive collapse. This paper utilizes a discrete element method (DEM) model to investigate the mechanism of the force variation in struts and diaphragm walls during excavation and progressive collapse based on the Nicoll Highway accident in Singapore. This study identifies dangerous time points, which occur after the excavation has reached a certain depth, leaving a layer of soil without a corresponding strut. At these points, the bottommost one or two installed struts and diaphragm wall are critical components that can trigger progressive collapse if they fail. To prevent this, two concepts are proposed and are validated by DEM simulation. The sparse upper and dense lower (SUDL) strut arrangement concept ensures progressive collapse resistance of the retaining structure at the bottom of the excavation. The concept of dynamic redundant struts (DRSs) utilizes redundant struts to provide temporary protection in the vulnerable sections of the retaining system during excavation. Alternating the installation and removal of DRSs creates dynamic redundancy, ensuring progressive collapse resistance throughout the construction process in a relatively economical way. Additionally, the DRSs can effectively reduce the lateral deflection of the retaining wall.

Behavior of textile‐reinforced concrete columns

AbstractThis work aims to investigate the behavior of textile‐reinforced concrete (TRC) members subject to compressive loads. An experimental program including concentric compression tests on I‐section columns with different lengths and simply‐supported ends was carried out. From compression tests, load versus lateral deflection curves obtained experimentally are reported along with maximum loads and apparent imperfections determined using the Southwell technique. Failure modes were characterized by excessive lateral deflections for longer columns, whereas concrete crushing failure due to combined bending and axial load occurred for shorter columns. Surrounding concrete was effective in restraining the textile reinforcement against buckling, allowing it to sustain the compressive loads. A single degree‐of‐freedom model accounting for normal‐moment‐curvature relation and tension stiffening behavior is validated against experiments and used to carry out a parametric study. Results show that the nonsway moment magnification method recommended by the ACI Code 440.11‐22 can be applied to TRC columns, although leading to overestimated second‐order effects.

Experimental Evaluations of Model Piles Subject to Inclined Loading in Sand

The structures that subjected to varying loads are supported by pile foundations. These loads consist of inclined and vertical loads. The main objective of this work is to experimentally investigate the effects of an inclined load on the lateral pile reaction and axial pile displacement for piles found in cohesionless soil. For this purpose, the slenderness ratios of model steel piles are varied by values of 11, 14, and 17. Moreover, the pile shapes involved in this study are H-pile, closed end circular and square. The experimental tests were conducted in sandy soil. However, the load inclination angle included in assessing the pile behavior were 0, 30, 45, and 60 from the vertical. In order to study the above parameters on the behavior of model pile, thirty-six experimental tests were carried out. Several findings indicated that the lateral pile deflection was highly influenced by increasing the load inclination. Further, the load inclination effect on the pile's ultimate bearing capacity is high which leads to a reduction in the pile's capacity. Additionally, the vertical displacement of pile is less than horizontal displacement when the pile is subjected to an inclined load of 45° and the model fails by horizontal displacement.

Pertinent Emplacement of Shear Walls to Diminish the Torsional Effects in Asymmetric-RC Framed Buildings

In seismic conditions, asymmetric structures typically experience lateral deflection. The magnitude of this deflection is dependent on various factors, including the configuration of the structural system, the mass of the structure, and the mechanical properties of the materials used. One critical factor that can reduce a structure's seismic resistance is torsion irregularity. To combat this, shear walls can be installed in the pertinent location to provide stability and stiffness to the structure. This study explores the seismic analysis of a G+10 storey asymmetric RC frame-shear wall structure using the response spectrum method as per ASCE7-16. The study encompasses six models with varying shear wall placements, with the initial model lacking a shear wall. The results are compared, and recommendations are made to avoid torsional irregularity destruction under seismic loads. Based on the analysis, Model-2 (shear wall in the periphery) shows the worst condition from the 1st storey through the 11th storey, possibly due to maximum eccentricity in upper storeys. In contrast, Model-5 (shear wall in core and corners) shows the best performance among all models, likely due to increased stiffness in the corners and core of the structure. Overall, this study contributes to the advancement of structural engineering practices by enhancing the understanding of complex interplay between torsional irregularity, shear wall placement, and structural asymmetry.

Research progress in the magnetic domain wall topology

Topological magnetic skyrmions, as information units, possess distinct advantages such as high reliability, enhanced integration, and low energy consumption. These novel topological characteristics offer critical material and technological support for the rapid development of information technology, 5G communication, and big data. However, the application of magnetic skyrmions in practical devices is severely impeded by certain limitations, including their stability dependence on magnetic field and the deflection caused by the skyrmion Hall effect under electric current. Consequently, exploring new topological magnetic domain structures and material systems suitable for application becomes a pivotal area of research. This paper primarily focuses on experimental studies utilizing high-resolution Lorentz transmission electron microscopy for &lt;i&gt;in situ&lt;/i&gt; real-space observation and manipulation of topological merons and skyrmions inside the magnetic domain wall, confirming the theoretical prediction of magnetic domain wall skyrmions in 2013. We has firstly achieved topological meron chains inside the domain walls by using the spin reorientation transition in two-dimensional van der Waals Fe&lt;sub&gt;5–&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;GeTe&lt;sub&gt;2&lt;/sub&gt; magnets, and systematically studied the dynamic behavior of domain wall topological magnetic domain structures under external electric and magnetic fields, filling the blanks in this research area. The important and special roles of magnetic domain walls are revealed at the same time. Then the GdFeCo amorphous ferrimagnetic thin film was designed and prepared based on the summarized mechanism with the domain wall meron pairs successfully reproduced. Moreover, the reversible topological transformation from domain wall meron pair to domain wall skyrmions has also been realized without external magnetic field during spin reorientation transformation as temperature changing. The results of micromagnetic simulation and electric experiments on the topological domains in domain walls would provided a strong basis and support for the future research.

Study on Seismic Performance of Reinforced Concrete High-Rise Building with Buckling Restrained Braces Dissipation Devices

Performance-based Seismic Engineering is the modem approach to Earthquake Resistant Design to control lateral deflection and inter-story drifts. It is a significant challenge to overcome in the execution of high-rise buildings. Since structures are subjected to lateral loads, the Utilization of dissipation devices such as the bracing, shear wall, and dampers are a possible method to enhance the structural performance of the high-rise building under load cases. These cases are varying to static and dynamic ones as Response Spectrum. Properly designed and detailed structures with dissipation devices have exhibited excellent performance during a severe earthquake. Lateral forces due to will be resisted in its plane. In continuation studies of reinforced concrete structure compared to the absorbing devices, Three essential reinforced concrete buildings were taken for analysis G+ 30 floors to cover the broader spectrum of high-rise building construction. Software ETABS carried out seismic analysis through Response Spectrum Analysis. The result highlights how structural damper systems perform much better than other systems with accuracy and exactness through the parameters of Displacement, Drift, Base shear, and Stiffness. Damper structures are more suitable for high-rise buildings and earthquake zones due to this study's results; maximum height of systems could be possible, which must be economically less expensive than steel structure of the same height.

Nonlocal strain gradient‐based nonlinear dynamics of sinusoidal impulsive actuated porous/piezoelectric multilayer energy nanoharvesters

AbstractThe applications of nanoelectromechanical systems integrating simultaneously the mechanical and electrical functionalities at nanoscale have been gotten wider in the last decade. The main objective of this exploration is to analyze the small scale‐dependent nonlinear dynamical feedback of multilayer energy nanoharvesters containing a graded porous passive core coated by piezoelectric facesheets under a sinusoidal impulsive external actuation. For this purpose, the technique of meshless collocation is constructed at the same time the nonlocal stress and strain gradient tensors without any necessary background meshes and integration procedure. It is found that by taking the nonlocal stress tensor into account, the average of extremum points of maximum lateral deflection increases from to , and from to for simply supported and clamped multilayer nanoharvesters, respectively. On the contrary, through considering the strain gradient tensor, the average of extremum values of the maximum lateral deflection reduces from to for the simply supported nanoharvester, and from to for the clamped one.Highlights Development a third‐order shear flexible nonlocal strain gradient (NSG)‐based plate‐type nanoharvester model Incorporating the role of nonlocal stress and strain gradient tensors in nonlinear dynamics of nanoharvesters Time‐histories of achieved voltage of sinusoidal impulsive loaded plate‐type nanoharvesters Influence of porosity on the NSG‐based nonlinear dynamic performance.

Evaluation of Soil Structure Interaction Effects on Seismic Response of RC Framed Buildings Using Simplified Method

In the current practice for the design of the building structure is done by considering the footing as fixed based. The mid-rise buildings having variation in storey height from 3- to 10-storey were selected for the research. In this research, analysis was done to study into the interaction between the seismic response of RC-framed buildings and the soil-structure for various soil types. To study the linear responses of the structures, the model was developed in FEM software SAP2000. The underneath soil was modelled by using direct method, where the soil is considered as solid element. The considered depth of soil was considered 30 m and the viscous spring dashpot were applied to avoid the reflection of seismic waves in soil medium along the effective horizontal soil boundaries. The seismic response variables such as maximum lateral deflection, inter-storey drift and fundamental time periods have been studied. SSI amplified the lateral deflection, inter-storey drift and time period of structure shifting the performance level from life safety to near collapse level. Fundamental time period of the first mode was increased by 23 % for very soft soil. The maximum lateral deflection of 10-storey building for very soft soil was amplified up to 282 % for Kobe and the performance level was shifted from life safety (1.5 %) to collapse level for all the considered model for soil type D . The performance level of structure was checked against the different soil types on varying storey height and finally a simplified method has been proposed to incorporate the effects of SSI in fixed base structures.

Structural behaviour and resistances of high strength concrete-filled stainless steel tube (HCFSST) beam-columns

This paper reports experimental and numerical investigations into the structural behaviour and resistances of high strength concrete-filled stainless steel tube (HCFSST) beam-columns under combined compression and bending. An experimental investigation was conducted on sixteen HCFSST beam-columns specimens fabricated from stainless steel tubes with two cross-section sizes and high strength concretes with four material grades, and included concrete cylinder tests, tensile coupon tests, initial global geometric imperfection measurements and eccentric compression tests. The test setups and procedures were fully reported and the experimental observations were discussed and analysed in detail. It was found that the plane cross-section assumption was valid for eccentrically loaded HCFSST sections and the lateral deflection distribution patterns for HCFSST beam-columns were approximately half-sine wave shapes. The test results were used in a subsequent numerical investigation for the validation of finite element models, which were then employed to conduct parametric studies to generate additional numerical data over a wide range of cross-section dimensions, member lengths and loading combinations. Based on the experimental and numerical results, the relevant design rules, as set out in the European code, American specification and Australian/New Zealand standard, were evaluated for their applicability to HCFSST beam-columns. The evaluation results revealed that the European code provided accurate but scattered failure load predictions when used for HCFSST beam-columns, while the American specification and Australian/New Zealand standard resulted in conservative and scattered failure load predictions.

Effects of Temperature on Axial Crushing Behavior of Circular Multi-Walled Tubes

In this work, the impact of temperature on the crushing performance of multi-walled tube (MWT) were investigated using a combined experimental, theoretical and numerical method. The MWT was fabricated using extrusion technology, and the temperature-dependent axial crushing experiment was performed on a hydraulic testing machine. The results show that the peak crushing force (PCF), the mean force (Pm) and the specific energy absorption (SEA) decreased near-linearly by 21.7%, 30.7% and 30.7% as the temperature increased from 25 °C to 250 °C, while the crushing load efficiency (CLE) was insensitive to temperature. The average forces obtained via numerical prediction, theoretical analysis and experimental testing were basically consistent. The numerical results indicate that varied temperature alters the number of dominant wavelets and the relative lateral deflections of MWT. In addition, compared with the competitive structures, the energy absorption property of MWT is excellent at high temperatures.

Symmetry-breaking response of a flexible splitter plate attached to a circular cylinder in uniform flow

Static and dynamic fluid–structure interaction of a flexible plate behind a stationary cylinder in uniform flow is explored for a body-to-fluid mass ratio of 10. Steady flow-structure computations for Re = 150, based on the diameter of cylinder and free-stream speed, reveal four regimes with respect to increasing flexibility of the plate. The plate does not undergo any lateral deflection in regime 1 beyond which it undergoes a symmetry-breaking bifurcation causing it to spontaneously deflect laterally. The curvature is of the same sign along the entire length of plate in regime 2 while it changes sign along the plate in regime 3. The lateral deflection, however, is still maximum at the plate tip. The location of maximum deflection moves away from the plate tip in regime 4. The evolution of flow structures including the strength of various standing vortices, with flexibility, is studied. The role of reattachment of flow on the surface of the plate and the modification of the pressure distribution is explored. The critical Re, beyond which the splitter plate spontaneously achieves a deflected shape, decreases with increase in flexibility. It is estimated to be Re = 122.33 for the limiting case of an infinitely flexible plate. Computations for dynamic fluid–structure interaction reveal several regimes of lock-in with different natural vibration modes of the plate and related hysteresis. No lateral bias in the time-averaged deflection is found during lock-in; it occurs in the desynchronization regime that precedes the lock-in regime with second mode. For the mass ratio considered, the bias in the static and dynamic simulations start at the same flexibility.