Horizontal Deflection Research Articles

Hydraulic characteristics of small-scale constructed wetland based on residence time distribution

ABSTRACT This paper designs and builds a small constructed wetland test site to study the internal hydraulic characteristics of different types of constructed wetlands, conducts NaCl pulse tracing experiments, and fits the residence time distribution (RTD) with the CSTRs+PFD model (Continuous Stirred-Tank Reactor model in parallel with Plug Flow with Dispersion model). The results showed that, among the six types of constructed wetlands, hydraulic parameters of horizontal subsurface flow constructed wetlands with baffles had the best performance, with a tracer recovery rate (F(t)) reaching 43.67% and hydraulic efficiency (λ) reaching 0.81. The addition of baffles slowed flow velocity, increased mean hydraulic retention time (Tm ) and peak residence time (Tp ), and reduced the short circuits phenomenon. The velocity of internal water flow increased during the horizontal and vertical deflections, which could well avoid the stagnation phenomenon caused by complicated flow state, thereby improving the hydraulic efficiency (λ). The CSTRs+PFD model can better fit the RTD of 6 different types of constructed wetlands. The peak value of the fitted curve, the time to reach the peak and the slope of the curve are all very similar to the measured RTD.

Comparative study of various flexible facing materials for soil nailed slopes

As the natural slopes along the roadsides and embankments are not stable due to sliding or collapse, a technique termed “soil nailing” is used to stabilize the natural or man-made slopes. A small scale physical model of soil nailed slope in well-graded sandy soil and inclined at 60° to the horizontal using four number of soil nails is prepared in the laboratory using different flexible materials as flexible facing namely Uniaxial Geogrid, Geotextile fabric, Coir mat, Fine Stainless steel woven wire mesh. The results of these soil nailed slopes with flexible facing materials and the soil nailed slopes with no additional facing are compared. The behavior of these soil nailed slopes is analyzed by applying extra surcharge with the help of a hydraulic jack for load application on the physical model. The strain produced in the inserted soil nails on stress application is determined using a multimeter with the help of the sensors bonded to the each soil nail. Also, the deflection of the soil mass in horizontal and vertical deflection is measured as it is clearly visible from the perplex sheet provided on the outline of the physical model. The stress, horizontal displacement and vertical displacement induced in all the materials is measured and compared. The fine stainless steel wire mesh took the maximum stress of 1.23 N/mm2 with minimum displacements and minimum strength of 0.492 N/mm2 was possessed by the slope without any facing material. Also, the other flexible materials like uniaxial Geogrid and coir mat possessed good strength and hence can be an effective alternate to strengthen existing or new slopes and provision of flexible facing materials in soil nailing technique further aids in slope stabilization.

Experimental Study of Lateral-Torsional Buckling of Class 4 Beams at Elevated Temperature.

The results of experimental research on lateral-torsional buckling of steel plate girders with slender web subjected to fire conditions are presented in this paper. The scope of the research covers four girders, three of which have been tested under high temperature conditions. The fourth girder has been used to determine the critical load resulting in lateral-torsional buckling of the considered element at room temperature. All the considered elements had identical cross sections and lengths; however, they differed in external temperatures applied and magnitude of measured geometrical imperfections. It has to be highlighted, that the experiments have been conducted subject to the anisothermal conditions, taking into account the uneven distribution of temperature in the cross section. An approach of this type represents a more accurate modelling of the structural component behaviour, when subjected to fire, as compared to the experiments conducted under isothermal conditions. Complete information on the development of research stand, conduct and results of particular tests are presented in this paper. The temperature–time curves for girder components, results of imperfection measurements and mechanical properties of steel are presented. The obtained critical temperatures and graphs of girder top flange horizontal deflection versus temperature are also included. The computer models developed for analysed girders are described in the paper as well. The results obtained with these models have been compared with experimental results. The computational models validated in this way constitute a basis for further parametric studies of lateral-torsional buckling in the domain of steel plate girders with slender web when subjected to fire conditions.

Refined orthotropic beam models based on Castigliano’s theorem and an approximate solution of the compatibility equation

This paper presents an extension of Castigliano’s second theorem for orthotropic beams. The notion “extension” in this context means to find more accurate results not only for the vertical deflection, but also for the horizontal deflection and the rotation angle. For this purpose the Airy stress function is calculated for an orthotropic rectangular strip based on the iterative approximation method from Boley-Tolins when distributed loads or shear tractions are assumed as surface loads. Hence all stress components can be derived from the stress function and may be inserted into the complementary strain energy. Computing the partial derivative of the complementary strain energy with respect to a scalar dummy parameter, the weighted displacement field components over the cross section are obtained. Finally the analytical results from the extended Castigliano theorem (ECT) are verified by two-dimensional (2D) analytical results for an orthotropic cantilever and a clamped-hinged beam and the outcome is also compared to Bernoulli–Euler and to Timoshenko results. The accuracy of the derived results is higher than that derived by the Timoshenko theory because the normal stress in thickness direction is properly taken into account. Moreover it is demonstrated that this lower order normal stress which is caused by distributed loads yields a mean horizontal elongation or shrinkage that is not considered by the Timoshenko beam theory. Hence, highly accurate formulations for laminated composite beams, involving sandwich-structures or multi-layered beams with imperfect bonding, may be derived from the present orthotropic beam model in the future.

Predicting the seismic response of the short structures by considering the Whale Optimization Algorithm

This paper presents a newly improved version of the Whale Optimization Algorithm based on quantum theory by optimizing the Artificial Neural Network for the ground response approximation problems in short buildings. Based on the literature, Artificial Neural Network does not provide a proper response of ground surface prediction in seismic load applications. Hence, the main idea of this study is to assess the utilization of the whale optimization algorithm for calculating the columns’ horizontal deflection in the short structure under notable considered seismic loading. The input database utilized in this paper is the Chi-Chi earthquake that is occurred in 1999 in Taiwan. To provide the train and test databases for the artificial neural network algorithm and whale optimization algorithm, Finite Element models are used. The inputs contain the Chi-Chi earthquake’s dynamic time, soil elastic modulus, dilation angle, Poisson’s ratio, unit weight, friction angle, bending stiffness and axial stiffness. Also the columns’ horizontal deflection in their highest level is considered as the output. The results showed the higher reliability of the proposed WOA in calculating the ground response and the column’s horizontal deflection in short buildings subjected to the earthquake loading.

Parametric study on Sheet Pile Walls in Layered Soils

Sheet pile wall is a retaining structure. It is used to retain the deep vertical cuts made in the earth, waterfront structures, cofferdams, and bridge abutments. The geotechnical engineering advantage of sheet pile wall is that it does not consume large base width like a retaining wall. When land acquisition problem arises, sheet pile walls are preferred. Sheet pile walls are subjected to rotational failure and flexural failure in layered soil. The rotational failure can be avoided by providing adequate depth of penetration. The in-front foundation soil generates passive force against the active or driving force from backfill soil. The flexural failure is avoided by providing one or more anchors at a particular location on the sheet pile, which in return reduces the maximum bending moments, the maximum shear force developed on the sheet pile and the depth of penetration. This makes the design of anchored sheet pile walls more effective in layered soil. This paper considers soft clay and loose sand as backfill, and stiff clay and dense sand as foundation soil. The outcomes of this research are cantilever sheet pile requires more depth of penetration to avoid rotational failure. For a height of ditch 6m, single anchor is sufficient but for a height of ditch 10m, double anchor required to reduce the depth of penetration, maximum bending moment, shear force, and horizontal deflection.

Analytical Comparison of Composite and Non-Composite through Type and Deck Type Steel Truss Bridges

In trusses, deck type and through type truss systems are generally provided with various member arrangements. To utilize the materials used in the trusses more efficiently, RCC decks are nowadays made composite with the truss members. In this paper, analysis of 72.0 m deck type and through type, non-composite and composite bridges is presented. The bridges are modelled using STAAD. Pro v8i software with truss members as beam element and deck slab modelled as four noded plate element. The loading on the bridge is done as per the provisions of IRC-6 and IRC-24. The composite deck effectively reduces the horizontal deflections due to lateral seismic and wind loads in both the truss systems. Decrement in vertical deflection of the truss system was also observed making the structure mode stiffer. Stresses in the members made composite with the deck slab were also reduced and hence resulted in material saving and decreased steel offtake. In the case of composite deck type bridges due to load sharing by the deck slab, the stresses in the top chord are reduced significantly hence eliminating the chances of buckling. Advantages of composite deck are better utilized in deck type bridge system compared to through type bridge system.

Long-term response of flexible pipe in sand trench due to consolidation of native clay

The finite element analysis are performed to investigate a long-term response of flexible pipe buried in sand trench embedded in native soft clay. The investigated long-term behaviors are due to effects of backfill soil structure rearrangement and native clay consolidation. The finite element results suggest that the short-term response of pipe depends strongly on trench widths but independent of trench depths due to the dependence of arching effect with trench width. However, the effects of trench width become less important for long-term pipe response. Moreover, the mechanism of this long-term response is likely due to backfill soil structure rearrangement, which occurs within a shorter time, not consolidation of native clay. The importance of finite element modelling of interface between sand backfill and clay trench and modelling of construction sequence on the obtained pipe-soil interaction are investigated. For long-term consideration, modelling of interface between sand backfill and clay trench is important; however, modelling of construction sequences is not so. Prism load seems to give better results for long-term load. Available analytical solutions cannot accurately estimate both vertical load and pipe deflection at short term for narrow trench due to a strong influence of arching effect after backfilling. At long term, Iowa formula under-predicts the horizontal pipe deflection by the ratios of 0.40–0.52 which correspond with a deflection lag factor DL of 1.9–2.5. The time lags of narrow trench obtained from this study are 1.6–1.9 and they become smaller for wide trench.

S wave Velocity Structure of the Crust and Upper Mantle Beneath Shanxi Rift, Central North China Craton and its Tectonic Implications

AbstractThe Shanxi rift is located in the central part of the North China Craton (NCC). With strong tectonic deformation and intense seismic activity, its crust‐mantle deformation and deep structure have always attracted wide attention. Using teleseismic events observed in a dense network of 610 temporary and 127 permanent stations in the central NCC, we obtained the crust‐mantle S wave velocity structures by the joint inversion method of receiver functions and surface wave dispersion data. Our results show that the crust thickens in the northern part of the Shanxi rift (41 km) and thins in the southern part (35 km). The Taiyuan and Linfen basins, located in the central part, have high‐velocity zones in the lower crust and upper mantle; beneath the Yuncheng basin in the south, there are low‐velocity zones in the lower crust and uppermost mantle (30–80 km); the Datong basin, located in the northern part of the rift, exhibits a wide range of low‐velocity anomalies in the middle to lower crust and upper mantle. We speculate that the destruction of the NCC and associated lithospheric thinning had a significant impact on the southern part of the rift, but is still in its early stage in the central part, which retains most of the craton features. An upwelling of the asthenospheric magma occurred beneath the western part of the Datong basin. The horizontal deflection of the asthenospheric flow causes low‐velocity anomalies in its surrounding area, which is consistent with LAB topography.

Analysis of Mixed-Mode I/II/III Fracture Toughness Based on a Three-Point Bending Sandstone Specimen with an Inclined Crack

The crack-propagation form may appear as an arbitrary mixed-mode fracture in an engineering structure due to an irregular internal crack. It is of great significance to research the mixed-mode fracture of materials with cracks. The coupling effect of multiple variables (crack height ratio, horizontal deflection angle and vertical deflection angle) on fracture parameters such as the stress intensity factors and the T-stress are the key points in this paper. A three-point bending specimen with an inclined crack was proposed and used to conduct mixed-mode fracture research. The fracture parameters were obtained by finite element analysis, and the computed results showed that the pure mode I fracture and mixed-mode fractures (mode I/II, mode I/III and mode I/II/III) can be realized by changing the deflection angles of the crack. The pure mode I and the mixed-mode fracture toughness of sandstone were obtained by a series of mixed-mode fracture experiments. The experimental results were analyzed with the generalized maximum tangential strain energy density factor criterion considering T-stress. The results showed that the non-singular term T-stress in the fracture parameters cannot be ignored in any mixed-mode fracture research, and the generalized maximum tangential strain energy density factor criterion considering T-stress can better predict the mixed-mode fracture toughness than other criteria.

A Method for Rapid Measurement of the Deformation and Spatial Attitude of Large Radar Antennas Inside Radomes

It is challenging to measure, analyze, and control the deformation and space attitude of antennas in narrow radomes through geometric measurement to ensure the accuracy of phased array radar application. In this manuscript, a method for rapid measurement of antennas by adopting the combination of photogrammetry system, laser tracker and total station was proposed. The photogrammetric method was used with a homemade auxiliary tool to measure and calculate the antenna’s deformation under different temperatures and pitch angles. Mapping relations between the instrumental coordinate systems of photogrammetry system, laser tracker and total station were established through common points, including target balls and reflectors. Coordinates of mark points on antenna surface were converted from photogrammetric coordinate system to laser tracker’s and total station’s coordinate system. Thus, antenna’s pitch angles relative to the local horizontal plane and deflection angles relative to the north of the engineering coordinate system were calculated. Planar fitting, coordinate transformation and space attitude calculation were all carried out in the Spatial Analyzer (SA) software. The photogrammetric method detected the antenna’s gravitational deformation sensitively, the maximum Root Mean Square Residual (RMSR) of the reference length was $54~\mu \text{m}$ , and that of the mark points was $59~\mu \text{m}$ , which was stably in line with its nominal accuracy. Deviations caused by coordinate transformation had no significant effect on the calculation of antenna’s spatial attitude, for the maximum deviation between the converted and measured coordinates in laser tracker’s coordinate system was 0.139 mm, and that in total station’s coordinate system was 1.037 mm, both of which were within reasonable limits of the derived theoretical maximum deviations between different instruments. As a result, the maximum deviation between the calculated value and servo system’s nominal value of antenna’s pitch angle was $59.4''$ , and that of antenna’s deflection angle was $91.87''$ . This method’s efficiency was greatly improved by about ten times compared with traditional methods through statistics and estimates.

Sensitivity Analysis of Distress Influence Factors on Steel-Plastic Compound Reinforced Retaining Wall

Abstract Based on the distress survey of the existing reinforced retaining wall in Harbin, this article summarizes the main forms of distresses. Taking the section with typical distresses as an example, the influences of fill properties, fill void, ribbon fracture, seepage, traffic load, and other factors on the horizontal deflection and axial force were analyzed by the finite element (FE) method. Causes of distresses of the reinforced retaining wall were systematically studied. Results showed that soil pressure, traffic load, seepage, and the combined action of many other factors are the main causes of retaining wall distresses. The sensitivity factors of horizontal displacement of a reinforced retaining wall are the cohesion and internal friction angle of filling soil. Moisture caused essentially by pavement cracks and seepage can result in the decrease of cohesion and internal friction angle, which are the important factors of outward-dipping deformation. Ribbon fracture, filling soil void, and traffic overload are the important factors leading to horizontal deformation of a retaining wall. According to the orthogonal experiment design, cohesion is the most significant factor for the horizontal deformation of a retaining wall, followed by the internal friction angle; the elastic modulus of foundation and the rest of the factors are not significant, which is consistent with the simulation result of the range analysis. The FE models show good predictability and are well validated by field tests and the orthogonal experiment. These models appear to work for similar reinforced retaining walls.

Finite Element Computation of Crown Deflection of Cracked Concrete Gravity Dam under Effect of Creep in Fracture Process Zone

The concrete dams contain micro-cracks and flaws, developed during the hardening of concrete. Under the influence of static and dynamic loads, tensile stress at the crack's end causes the crack to grow, leading to structural failure. In the present study, a Finite Element (FE) computation is present to account for an effect of creep and non-linear stress-strain behavior in the fracture process zone (FPZ) for analyzing the horizontal deflection of the crown of a dam. The model test was perform for an old existing concrete dam for deflection of the dam's crown for a single crack and the results were compare with field data. The present model successfully simulates the effects of non-linear stress and creep in FPZ on the horizontal dam-crown deflection. It concludes that the analysis of dam stability in conventional methods must include the stress field behavior in FPZ.

Structural dynamics of basaltic melt at mantle conditions with implications for magma oceans and superplumes

Transport properties like diffusivity and viscosity of melts dictated the evolution of the Earth’s early magma oceans. We report the structure, density, diffusivity, electrical conductivity and viscosity of a model basaltic (Ca11Mg7Al8Si22O74) melt from first-principles molecular dynamics calculations at temperatures of 2200 K (0 to 82 GPa) and 3000 K (40–70 GPa). A key finding is that, although the density and coordination numbers around Si and Al increase with pressure, the Si–O and Al–O bonds become more ionic and weaker. The temporal atomic interactions at high pressure are fluxional and fragile, making the atoms more mobile and reversing the trend in transport properties at pressures near 50 GPa. The reversed melt viscosity under lower mantle conditions allows new constraints on the timescales of the early Earth’s magma oceans and also provides the first tantalizing explanation for the horizontal deflections of superplumes at ~1000 km below the Earth’s surface.

THE IMPACT OF THE DISTRIBUTION OF OBSERVATIONS ON TERRESTRIAL LASER SCANNER SELF-CALIBRATION QUALITY

Abstract. Terrestrial laser scanning (TLS) instruments find routine use for a range of precision engineering measurement applications. Depending on the accuracy requirements for a specific project, the instrument may require self-calibration to determine systematic error model terms. One of the goals of first-order network design for self-calibration is to acquire observations throughout the full instrumental field-of-view. Experience calibrating TLS instruments has demonstrated that while this goal can be achieved for horizontal deflection angle observations, it is seldom realized for the vertical angle observations. This paper presents results from a preliminary investigation into the impact of the distribution of vertical angle observations on the estimation of two critical systematic error parameters in TLS instruments: the collimation axis error and the trunnion axis error. First, a model to characterize the empirical observation distributions is developed. The model is a function of a single shape parameter that quantifies observation dispersion. Then, a means to estimate the impact of the distribution on the parameter estimation is developed. Results from six real datasets show the distribution model characterizes the overall general trend of the observations. Simulated results show the relative independence of the collimation axis error and the strong dependence of the trunnion axis error on the shape parameter.

Comparative Evaluation of Concentric Bracing Systems for Lateral Loads on Medium Rise Steel Building Structures

To resistance, the lateral load from wind or an earthquake is that the reason for the evolution of varied structural systems. Because, when a medium or any multi-level structure is exposed to horizontal or torsional deflections under the action of seismic burdens. Lateral stiffness is a major consideration in the design of the buildings. In addition to this, many existing steel buildings and reinforced concrete buildings for which the weak lateral stiffness is the main problem; should be retrofitted to conquer the insufficiencies to resist the lateral loading. Lateral load resisting systems are structural elements providing basic lateral strength and stiffness, without which the structure would be laterally unstable. The unstable nature of the structure is solved by the fitting arrangement of bracings systems. A bracing system is that forms an integral part of the frame. Thus, such a structure has to be analyzed before arriving at the best type or effective arrangement of bracing. Bracing is a highly effective strategy of resisting lateral forces in a frame structure. In this document, a ten-story building with incorporated bracing systems is analysed using ETABS 2016 analysis software as per Eurocode and Ethiopian Building Code Standards (EBCS). Then, the lateral displacement is evaluated under each of the bracing types.

Floating slab track efficiency tests in Moscow underground

The article deals with field tests of a floating slab track (FST) – a railway track structure used in Moscow underground. The upper track structure to be tested was erected in 1977 and consists of a concrete track slab with embedded wooden sleepers, rails R50 with “metro” fastenings and a series of rubber isolators, that support the concrete slab and transfer all the loads down to the tunnel casing. The aim of the test is to get substantial experimental data and understand its static and dynamic behaviour in order to use in further development and verification of FST’s design models. During the test under moving trains different load parameters are acquired: dynamic vertical and horizontal forces, rail & slab deflection and acceleration at different points on the slab and tunnel casing. On the basis of this multifactorial survey, verification data is acquired and weak points of the FST are investigated.

Numerical assessment of laminated cantilevered glass plates with point fixings

Cantilevered laminated glass plates, used e.g., in balconies and freestanding glass balustrades, are an example of the use of glass in modern architecture as a structural material. In order to fulfil its scope of preventing building occupants from failing out, the cantilevered plate must be able to transfer the loads imposed from the crowd pressure or by people in motion to the main structure of the building. Since a cantilevered plate is critical in the joint, the design of the connection between the glass pane and the supporting structure is of primary importance for the performance of the system. The paper investigates the behaviour of cantilevered laminated glass plates with point joints, accounting for both bolted and adhesively bonded fixings, and different designs of the joint system. The static and impact tests prescribed in the Italian standard UNI 11678 are numerically simulated and the results analysed in terms of the horizontal deflection and maximum peak stress of the glass pane. Under static loads, bonded joints reduce stress concentration and increase the lateral stiffness of the cantilevered plate in comparison to bolted fixings, but the results are highly sensitive to the stiffness of the interlayer. Increasing the vertical distance between the fixing rows is shown to have contrary effects on the stress concentration around bolt holes depending on either static or dynamic loading is considered.

Improved understanding of beamlet deflection in ITER-relevant negative ion beams through forward modelling of Beam Emission Spectroscopy

NBI systems for the ITER tokamak will require large (1 m × 2 m cross section) and powerful negative ion beams to achieve the required 16.5 MW per beamline. Such negative ion beams can only be created from the combination of many individual beamlets – 1280 per beam in the case of the ITER heating neutral beam (HNB). These beamlets are required to have a core divergence of less than 7 mrad. However in these large and powerful beams, individual beamlets cannot be measured, and divergence values can only be obtained for a mixture of multiple beamlets.To investigate this, experiments were performed at the BATMAN Upgrade (BUG) test facility, a negative ion source roughly 1/8 the size of the ITER HNB. Through Beam Emission Spectroscopy (BES) measurements, and synthetic diagnostic results from the code BBCNI, insights into the effects of beamlet mixing on experimental observations have been obtained. For a single beamlet, it is expected that BES measurements obtain a Doppler shifted Hα peak with a roughly Gaussian profile, the width of which is related to the beamlet divergence, and the central wavelength is a function of the beamlet energy and the BES observation angle. In experiments at BUG, it was observed that the amount of Doppler shift in some BES lines of sight depended on the ratio of voltages applied to the grid system, even though the total voltage remained the same.By combining diagnostic data from the experiment and forward modelling from BBCNI, it was found that the change in Doppler shift for the affected lines of sight was caused primarily by changes to the horizontal deflection of beamlets by uncompensated magnetic fields – termed ‘zig-zag’ deflection due to the alternating polarity by aperture row. The amount of Doppler shift was further modulated by the beamlet divergence, which affects the amount of beamlet mixing within the BES lines of sight.

Effect of the Parking Lane Configuration on Vehicle Speeds in Home Zones in Poland

Nowadays, traffic calming measures that are designed to influence the drivers’ behaviour in the first place and thus make them slow down (and increase the safety of traffic as a result) are used increasingly often in traffic engineering. As a rule of thumb, carefully planned street geometry and street furniture should advise the drivers of the traffic calmed area ahead of them, which makes them reduce the vehicle speed by influencing their perception. One of the most common treatments are road narrowings and horizontal deflections of the route of travel. The reduction of the vehicle speed increases the driver’s central visual area, which results in earlier and easier spotting of pedestrians that are about to cross the roadway. A reduction of noise and exhaust emissions is an additional benefit. However, the current sustainable design guidelines are not specific regarding how often the route should be deflected by alternate parking lanes and how frequently they should be placed in the home zones (woonerven in Dutch) in order to achieve the desired reduction of vehicle speed, noise, pollution, and exhaust emissions. This being so, the authors carried out a speed survey research on a chosen street that includes woonerf design features, as typically used in Poland, with carriageway narrowings being created by parking lanes differently sited along its length. Several speed measuring devices were deployed to automatically and simultaneously measure and record the vehicle speeds and volume of traffic at different test locations. The measurement data were subjected to statistical analyses, including conventional statistical tests. The alternative hypothesis, proposing that the vehicle speeds depend on the configuration of parking lanes and carriageway narrowings was confirmed in almost all cases. The results have confirmed that the siting of parking lanes is a relevant factor as far as speed reduction is concerned, with the degree of this reduction depending on the remaining travel lane width.