Plate Wall Research Articles

Multi-storey precast retaining walls to prevent landslides: derivation of the basic formula

Landslides can involve both large and small soil masses. Many geotechnical researchers focus on large-scale landslide problems. The retaining walls required for large landslides also involve large dimensions. The national standards also only cover the dimension of retaining needed to prevent large landslides. There are landslides that only involve small masses of soil. For this reason, the needed retaining walls are also in small dimensions. Small retaining wall dimensions do not need to follow national standards for maintaining the efficiency and effectiveness of application. In this paper, a precast retaining wall is designed which is used to retain soil on a relatively small scale. The designed retaining wall can be used also in multi-level to restrain the larger landslide. There are three main elements of the retaining wall: base plate, wall plate, and connector beam. The retaining wall elements are made of concrete material with bar reinforcement and wire mesh. The weight of each wall element is less than 50kg so it is portable. The wall prototype has been made and is ready to be applied in the areas with potential landslides.

Analysis of the Sound Field Characteristics of a Muffler at Different Flow Conditions

To reduce the noise in a pump piping system and increase the usage time of equipment, a new type of porous muffler is proposed in this paper. A water guide cone is incorporated into the muffler structure, which may help to redirect the fluid media in the piping system. The porous structure is adapted from a muffler shell, water cone wall and round bottom plate. According to this structure, the muffler sample is made, and a pump pipeline system test bench is set up. The outlet noise of the pump pipeline system is measured after installing the muffler. At the same time, the muffler is numerically simulated by combining computational fluid mechanics and Lighthill acoustic theory. The characteristics of the flow field and external sound field under three different flow conditions of 200 m3/h, 400 m3/h and 600 m3/h are assessed. The numerical simulation results show the same dominant frequency and trend as the experimental results. The rationality of the numerical simulation is verified. Research shows that: the level of sound pressure at the muffler's outlet is lower than at the inlet, causing muffling, and the characteristics of a quadrupole sound source appear at the outlet. The proposed muffler has a certain effect in reducing noise in the pump pipeline system.

Numerical study of perforated steel plate shear walls in staggered pattern

Steel plate shear walls (SPSW) consist of steel plates that are directly connected to columns and beams. The steel plate used as the filler is a thin and slender. One option to reduce the steel plate capacity is to provide perforations in the web plate. In this study, the parameters analysed were the influence of the perforation area on the arrangement of the staggered hole patterns on the steel plate panel. This study uses a numerical method. The result of the research is an analysis that explains the relationship between the percentage of perforation area on the load capacity and the stiffness degradation of the steel plate shear walls. The steel plate model is given a circular perforation with a diameter of 50 mm. The specimens were analysed at different number of perforations with a plate thickness of 1 and 2 mm. The results showed that every enhancement number of perforations, the load capacity and elastic stiffness will decrease. Changing the plate thickness from 2 mm to 1 mm, the load capacity also decreases. The initial stress distribution occurs on the diagonal side of the shear wall plate and then spreads to all parts of the shear wall plate.

Numerical Simulation and Optimization of SCR-DeNOx Systems for Coal-Fired Power Plants Based on a CFD Method

In order to solve the problem of the uneven distribution of the flow and ammonia concentration field in the selective catalytic reduction (SCR) denitrification system of a 660 MW coal-fired power plant, a three-dimensional computational fluid dynamics (CFD) model was established at a scale of 1:1. The existing flow guide and ammonia fume mixing device were then calibrated and optimized. The relative standard deviation of the velocity field distribution upstream of the ammonia injection grid (AIG) was optimized from 15.4% to 9.9%, with a reasonable radius of the deflector at the inlet flue elbows, and the relative standard deviation of the velocity field distribution above the inlet surface of the first catalyst layer in the reactor was optimized from 25.4% to 10.2% by adjusting the angle between the deflector and the wall plate of the inlet hood. Additionally, with the use of a double-layer spoiler ammonia fume mixing device, the relative standard deviation of the ammonia mass concentration distribution above the inlet surface of the first catalyst layer in the reactor was optimized from 12.9% to 5.3%. This paper can provide a valuable reference with practical implications for subsequent research.

Boundary plate influence on tie bars axial force demands in composite plate shear walls‒concrete filled

In composite plate shear walls–concrete filled (C-PSW/CF), there is an indeterminate flow of force between concrete, steel plate and tie bars. Finite element methods (FEM) are frequently used to verify this force flow. The theoretical models available in the literature to predict the tie bar maximum axial force demands were based on walls without boundary plates. The finding in this study is intended to help understand whether current theoretical approaches are conservative and can be applied to boundary plate walls as well. Within the scope of this study, tie bar axial force demands for walls with boundary plates consisting of planar and round shapes and without boundary plates were investigated and compared. For this, a previously benchmarked finite element (FE) wall model was considered and configured to have no boundary plate and have planar and round boundary plates. FE models were analyzed under monotonic lateral displacement up to 4% drift ratio. Passive lateral pressures and transverse force variations on the planar and round boundary plates were investigated.

Performance and strength analysis of concrete-encased steel plate walls under tensile-flexural-shear load

When located at the base of a building experiencing high-intensity earthquakes or bi-directional earthquakes, shear walls may be tensile, resulting in tensile-flexural-shear (TFS) stress states after lateral load coupling. The Chinese code proposes the embedded steel to counteract such issues, but there are few relevant studies. Six concrete-encased steel plate (CES) walls were tested under the TFS load to investigate the effects of axial tensile ratio and steel content on seismic behavior. The results showed that TFS specimens failed in tensile flexural-shear mode. Compared to the tension-free specimen, TFS specimens with an axial tensile ratio of 2.5 had 21%, 56%, and 40% lower shear strength, initial lateral stiffness, and ductility. Comparatively, increasing the steel content in the boundary elements effectively reduced the strengthening effect of steel and the brittle fracture potential of boundary elements induced by TFS load, thus enhancing the overall behavior by 15–19%. Furthermore, the failure mechanism was proposed based on the development of deformation and strain. It demonstrated that the maximum principal tensile stress in the web caused severe shear strength degradation and highlighted the importance of the dowel action through the crack interface, depending on the variables. Through the comparative analysis of the shear strength design formulas for eccentric tensile CES walls, the steel proportion was proposed as a modified factor in Chinese code for better estimation.

Experimental investigations into the effusion plate wall temperature of impingement/effusion cooling systems for gas turbine combustors

Cooling technologies are playing critical roles in the development of advanced gas turbine combustors. The present experimental investigation has studied the effects of geometric factors such as gap distance, impingement hole diameter, and effusion hole arrangement on the wall temperature of a novel impingement-effusion cooling system. The wall temperature of the effusion plate was directly measured by high-precision thermocouples. The wall temperature distribution of the cooling unit was obtained by biharmonic spline interpolation based on the measured temperature data. The cooling performance of cooling systems with different structures under different working conditions was compared. The experimental results indicate that the increase of gap distance weakens the strength of impinging jet, and the overall cooling performance decreases, accordingly. The smaller the diameter of the impingement hole is, the weaker the cooling film is, leading to a poor overall cooling performance at the same cooling airflow. However, better overall cooling performance can be obtained at the same blowing ratio at the cost of much more cooling airflow. Dense and uniform effusion hole arrangement has a very favorable impact on improving the cooling film quality and cooling performance.

Performance of concrete-filled double-skin shallow-corrugated steel plate composite walls under compression-bending load

This paper presents the study on the performance of concrete-filled double-skin shallow-corrugated steel plate composite walls (CDSCW) under combined compression and in-plane bending, where the CDSCW is composed of the concrete-filled double-skin shallow-corrugated steel plate wall (CDSW) and rectangular concrete-filled steel tubular (CFST) columns. The experiments on full-scale specimens show that the concrete and steel work together well under the combined loading, and the inner concrete is effectively confined by both steel tubes and shallow-corrugated steel plates. The numerical model is established for the CDSCW and the feasibility is verified by comparing with the test results. The equations for the resistance of composite wall under combined compression and bending are proposed through an extensive parametric study, and the validity and the reliability of the design methods are discussed. It is concluded that the proposed design methods can reasonably predict the resistance of CDSCW under combined compression and in-plane bending.

Key Technology for Construction of Steel-concrete Composite Suspending Cofferdam without Bottom Cover for Platform of Coastal Intercommunication Project

<p>Many bridge piers were built in the Coastal Interconnection Project of the Ningbo Section of the Hangzhou-Ningbo Expressway Double Line. Affected by the tides at the bridge site, the high pile caps are constructed using a suspending cofferdam without a bottom cover. Based on the consideration of various factors such as construction difficulty, safety, cost and construction period, etc. A cement structure is generally adopted as the floor of the suspended box cofferdam. The steel-concrete combined hanging box cofferdam without bottom cover adopts the structure of steel wall plate and prefabricated cement floor, and the partition wall plates are connected by bolts. The steel-concrete composite suspending cofferdam adopts the prefabricated bottom plate and wall plate. The construction sequence is listed as follows: First, weld the load-bearing corbel on the steel casing, and then hoist the prefabricated bottom plate to the steel casing corbel in blocks. Pour the wet joint between the prefabricated bottom plate and install the side plate. After that, pour the cushion after welding the shear plate. Finally, carry out the construction of the cap. During the construction of the project, the connection method between the wall plate and the bottom plate was optimized. The connection of the fine-rolled rebar hanger rod was changed to the steel bar pair pulling, which improved the construction efficiency significantly.</p>

Numerical Simulation of Deformation and Failure Process of Tunnel Surrounding Rock Based on Different Constitutive Models

Based on five different constitutive models, the progressive failure process of deep hard rock was simulated, and the plastic zone, shear strain increment high-value zone, horizontal displacement, and maximum principal stress distribution of surrounding rock were obtained. The calculation results show that the plastic zone of surrounding rock calculated by MCSS and HBSS models is mainly concentrated in the floor and vault of the cavern, and the sidewall is not damaged. There is no shear zone in the surrounding rock, and the magnitude of horizontal displacement is 10-4. In the L-CWFS model, the hysteresis cohesion of friction strengthening is weakened, and the initial friction angle is 0. The calculated plastic zone runs through the surrounding rock, and the whole section is destroyed. The order of magnitude of the horizontal displacement extremum is 10-3. The MC-HB model simulates the spalling failure of the side wall, and the strain localization of the side wall is not obvious, and no shear band is formed inside the surrounding rock deeply. The N-CWFS-TSS model simulates the buckling failure process of the straight wall plate crack. A shear band is formed at the bottom of the straight wall and penetrates into the interior of the surrounding rock. The strain localization is obvious and the order of magnitude of the shear strain increment is 10-2. The calculation results are consistent with the results of laboratory tests and field observations, and the failure mechanism of the compression-shear-tensile-shear composite in the progressive failure process of the surrounding rock is clarified.

Response of thin walled transversely stiffened clamped circular plates under uniform impulsive loads

Paper presents numerical models based on detailed characterization of various uncoupled damage models in a finite element analysis (FEA) setup to assess large deformations and observed ductile fracture failure modes of fully clamped circular plates as well as transversely stiffened circular plates in cross stiffened configurations under uniform impulsive loads. The numerical schemes have been based on a detailed definition of the constitutive properties based on inverse FEA simulations of the uniaxial tension test for the calibration of material and failure parameters. Experiments have been conducted using two types of freshly prepared mild steel uniaxial tension test specimens covering the envisaged range of stress tri-axialities to establish the steel plate material and fracture characteristics necessary for the calibration of the presented phenomenological damage models. Published results based on extensive experimental works by various authors on response of thin walled clamped circular plates under transversely applied uniform air blast loads, manifesting in large plastic deformations, thinning and tearing under various ductile fracture modes, have been used in the performance assessment of presented numerical models and procedure, which incorporate different damage models including temperature effects due to plastic dissipation. Based on evaluated performance of the discussed failure models within the FEA setup, a hybrid damage model with a tri-axiality based two part ductile fracture locus has been proposed, which shows very good correlation with the published experimental results, presented in terms of non-dimensional parameters over a wide range of impulsive loading. The validated numerical setup using the proposed hybrid damage model has also been used to predict the effect of transverse cross stiffened configurations of flat bar stiffeners on large deformations and ductile fracture of clamped circular plates under transverse uniform impulsive blast loads, along with some key insights in the evolution of plastic zones and damage progression.

Experimental study on drag reduction control of porous media wall turbulence

In order to study the control law and effect of the related mechanism of porous media on the turbulent drag reduction of a plate wall, experimental research of a plate laid with porous media was carried out in a low-turbulence, re-flow wind tunnel. First, the hot wire was used to acquire the time-averaged statistics and fluctuation data inside the boundary layer on the plate surface by single point measurement. Then, the fluorescenct oil flow was applied to obtain the global skin friction distribution downstream of the porous media. Finally, through Time-resolved Particle Image Velocimetry technique, the normal velocity flow field on the surface and the structural information of the near-wall strip were captured in quantitative terms, and the Dynamic Mode Decomposition (DMD) was adopted to analyze the strip’s structural features with the mode reduction. The results showed that the drag reduction effect of porous media had a trend of first increasing and then decreasing in the flow direction, with the maximum drag reduction rate on the surface of porous media. Meanwhile, the porous media changed the internal structure of the turbulent boundary layer, reduced the velocity gradient of the viscous bottom layer, and decreased the momentum exchange between the inner and outer layers, which suppressed the development of large-scale strip structure and promoted the lift of the spanwise vortices. The results of DMD analysis further explained that the porous media could effectively weaken the strip energy fluctuation and accelerate its spatio–temporal evolution process. Moreover, the second and higher order modes could reach a stable state in shorter time.

Sinus mucosal healing pattern according to pterygomaxillary disjunction type after Le Fort I osteotomy.

During Le Fort I osteotomy, the separation of the pterygomaxillary junction (PMJ) is a difficult procedure for most surgeons because it is invisible. In this process, damage to the posterior structures constituting the sinus or those adjacent to it, including the maxillary sinus posterior wall and pterygoid plate, may occur. We would like to investigate the effects of this on the inside of the maxillary sinus after surgery and whether there are complications. One-hundred patients who underwent Le Fort I osteotomy from 2013 to 2020 using cone-beam computed tomography images were classified into two groups (clean-cut type and fractured type) according to the PMJ cutting pattern. In addition, the mucosal thickness in the maxillary sinus was divided into preoperative, postoperative three months, one year, and the change over the course of surgery was evaluated retrospectively. Of the total 100 cases, the clean-cut type numbered 28 cases and the fractured type totaled 72 cases. Among the fracture types, part of the sinus wall and the pterygoid plate were broken in 69 cases, and the maxillary sinus posterior wall was detached in three cases. There was no statistically significant difference in sinus mucosal thickening between the clean-cut type and fractured type of the PMJ, three months and one year after surgery between the two groups. However, there was a significant difference in sinus mucosal thickness at postoperative one year in the case where a partial detachment of the maxillary sinus posterior wall occurred compared to not. Even if there is some damage to the structures behind the PMJ, it may not be reasonable to spend some time on the PMJ separation process considering the overall postoperative complications, if there is no significant difference inside the sinus, or increased probability of postoperative complications.

Damage Mode Analysis of Steel Box Structures Subjected to Internal Blast Loading

Steel box structures widely exist in vehicles, ships, and buildings, and internal explosions are one of the primary ways to destroy such targets. In this study, a rapid prediction method for the damage degree evaluation of steel box structures subjected to internal blast loads was proposed. First, the main influencing factors were identified through dimensionless analysis. Next, numerical simulations were conducted to further investigate the key influencing factors and different damage modes that were classified according to their characteristics. The non-dimensional Din* for damage analysis applicable to the internal explosions and the equations describing the deformation of the wall plate were proposed, followed by a comparative study of the damage features of anisotropic box structures with different structural dimensions. The influence of the coupling relationship between structural dimensions and blast loads on the damage modes was analyzed and three competing mechanisms of material failure were studied to analyze and classify the mode of breach expansion. Finally, a large number of experiments were analyzed to verify the analysis method.

Three-dimensional bubble jetting inside a corner formed by rigid curved plates: Boundary integral analysis

Three-dimensional dynamics of a transient bubble inside a corner formed by two rigid curved parabolic plates (walls) is studied numerically using boundary integral method (BIM) based on the potential flow theory. The bubble dynamics, including the expansion and collapse phases until the jet impact, are investigated for different corner angles associated with different focal lengths k of the parabolas. However, for all the simulations, the dimensionless initial vertical standoff distance of the bubble’s center from the corner edge (h∗) is fixed at 4. The bubble remains almost spherical during expansion, except for parts of its surface that flattens near the walls. When the bubble is initiated at the bisector plane of the two intersecting walls, it oscillates symmetrically with respect to the bisector plane and becomes oblate during the late stages of the collapse phase. A high-speed liquid jet forms towards the end of bubble collapse, pointing to the corner. If the corner angle decreases, the bubble becomes more oblate along the bisector plane making the ensuing liquid jet wider and slower. In addition, a bubble initiated closer to one of the two walls is mainly influenced by the closer wall, oscillates non-symmetrically with respect to the bisector plane and the liquid jet formed in this case is inclined towards the closer wall due to the greater Bjerknes force of that wall.

Seismic Behavior of Box Steel Bridge Pier with Built-In Energy Dissipation Steel Plates

Based on the design concept of earthquake-resilient structure, a new-type of box-shaped steel piers with embedded energy-dissipating steel plates was proposed. Quasi-static tests of 6 box-shaped steel pier specimens under variable axial pressure and cyclic horizontal loading were carried out. By analyzing the failure mode, load-displacement hysteretic curve, skeleton curve, displacement ductility coefficient, stiffness degradation characteristics, strength degradation coefficient, and cumulative hysteretic energy, the effects of setting energy-dissipating steel plate, axial compression ratio, and thickness of energy dissipation steel plates on the seismic performance of new-type steel piers were discussed. Finite element models of steel bridge piers were established and compared with the test results. The analysis results using FEM agree well with the test results. Results show that the setting of energy-dissipating steel plates can effectively improve the ductility, deformation capacity, and energy-dissipating capacity of box-shaped steel piers, and effectively delay buckling deformation and cracking of wall plates. The steel plate near the bolt hole of the wall plate at the root of the new-type of box-shaped steel piers is easy to crack due to stress concentration, resulting in a rapid reduction of the maximum bearing capacity of the specimens. With the increase of axial compression ratio, the bearing capacity, energy-dissipating capacity, and earthquake-resilient capacity of the specimens increase. The smaller the thickness of the replaceable energy-dissipating steel plates, the smaller the bearing capacity and faster the stiffness degradation of the specimens become, while the ductility and energy-dissipating capacity of the specimens are improved. The axial compression ratio and the thickness of the energy-dissipating steel plate have relatively little effect on the strength degradation of the specimens. In order to facilitate the popularization and application of the new-type steel piers, formulas were also established to calculate the bearing capacity and displacement ductility factor of the new-type of box-shaped steel piers.

수중방사소음 예측을 위한 선체 접수판의 가속도 분포에 관한 연구

In order to manage a ship’s underwater radiated noise, it is necessary to monitor it through a sensor attached to the hull. The underwater radiated noise can be predicted using the acceleration levels and radiation efficiency of the submerged plate. The areas of submerged plates are too large to be covered by a limited number of sensors. Moreover, some areas are inaccessible due to the tank structure on the bottom of ship. For accurate noise prediction, numerical calculations and measurements are used to investigate the appropriate number and locations of accelerometers. Numerical analysis shows that the vibration level changes sensitively with position. The acceleration levels obtained by all submerged plates are different from those by submerged side wall plates only. This means that the sensor location should be chosen so that errors are minimized when predicting under-water radiated noise. Vibration distribution is studied by measurement. Owing to the constraint of the number of channels, only the longitudinal distribution is investigated. Acceleration has different levels depending on location and frequency. Appropriate numbers and positions are suggested to represent the acceleration level of the entire submerged plate.

The prediction of residual life of liquid-storage tank considering the tank wall surface state

PurposeThe purpose of the paper is to predict the residual life of liquid-storage tank to ensure safety and long-term service life of the structure.Design/methodology/approachThe paper carried out the stress analysis of the wall plate and bottom plate of the liquid-storage tank, and the influence of circumferential stress on the tank is considered. On the other hand, considering the influence of the tank wall surface on the tank life, based on the Paris law, the surface processing coefficient and surface roughness coefficient are introduced to improve the Paris law.FindingsThe effectiveness of the improved model is verified by comparing with theoretical and experimental data, which provide a new method for the prediction of the remaining service life of the tank. Combined with the fatigue crack data in the test report and the calculated circumferential stress, the residual life of the storage tank is predicted.Originality/valueThe improved model provides a new method for the prediction of the remaining service life of the tank.

Chemical reaction and Soret effect on an unsteady MHD heat and mass transfer fluid flow along an infinite vertical plate with radiation and heat absorption

In the current investigation, it is anticipated to examine the influence of heat absorption and radiation on an unsteady transient MHD heat and mass transfer natural convective flow of an optically thin non-Grey Newtonian fluid through an abruptly started infinite vertical porous plate with ramped wall temperature and plate velocity in the presence of Soret and chemical reaction of the first order is solved precisely. Using the similarity variables, the governed PDE's are converted into dimensionless governing equations and they are solved numerically by employing the finite element technique. Numerical calculations and graphs are used to illustrate the important features of the solution on fluid flow velocity, heat, and mass transfer characteristics under different quantities of parametric circumstances entering into the problem. Moreover, we computed the physical variables such as the coefficient of drag force, rate of heat, and mass transfer. The findings indicate that when the thermal radiation parameter increases, the thermal boundary layer becomes thinner. To establish the veracity of our present results, we compared them to previously published research and found substantial concordance.

Platymerella—a cool-water virgianid brachiopod fauna in southern Laurentia during the earliest Silurian

AbstractPlatymerella from the lower Red Mountain Formation in Georgia and Tennessee, the Bowling Green Dolomite of west-central Illinois, and the Elwood Dolomite of northeastern Illinois represents a paleosubtropical, cool-water occurrence of virgianid brachiopods in Laurentia during the early Silurian (middle–late Rhuddanian). These occurrences were located in the southern Appalachian foreland basin and the distal end of the Sebree Trough, likely subjected to frequent cool-water current and upwelling from Gondwana. Compared with broadly coeval species of Virgiana from lower paleotropical to equatorial latitudes, Platymerella has significantly smaller, dorsoventrally flattened shells, with subequal ventral and dorsal umbones and beaks that extend only slightly above the hinge line. Relative to its shell size, however, Platymerella has more prominent thickening of the shell wall, median septum, spondylium, and hinge plates than Virgiana, resembling more closely the extravagant shell thickening of Tcherskidium and Proconchidium from the Late Ordovician (late Katian) equatorial regions. The thickening of hinge plates resulted in the formation of a pseudocruralium, which separates Platymerella from Virgiana. In latest Ordovician–earliest Silurian virgianids, there was a general morphological gradient toward a smaller shell, reduction in the ventral-valve convexity, and reduction in the size and height of the ventral umbo from paleoequatorial to southern subtropical regions, with Platymerella representing the most southerly forms.