Triangular Plan Research Articles

Experimental and numerical study of wind effect on an ultra‐thin concrete triangular plan shell structure

AbstractSelf‐supporting concrete shell structures are highly efficient in distributing loads, which can result in very reduced thicknesses (ultra‐thin), giving them remarkable slenderness. Due to their geometric complexity, it is difficult to predict how they interact with wind action. The main aim of the present study is to assess the mean surface pressure coefficient distribution in a shell with a triangular plan shape and three supports for different angles of wind incidence. To determine the distribution of surface pressure coefficients and lift and drag force coefficients, an experimental study was carried out in a wind tunnel, and a numerical simulation study was performed through computational fluid dynamics. The experimental and numerical results were analyzed and compared, and making it possible to identify the most critical surface zones and wind incidences when the shell is under the wind action.

Flow Rate Capacity Improvement of Triangular Plan Form Sharp Crested Weirs

Flow Rate Capacity Improvement of Triangular Plan Form Sharp Crested Weirs

Hydraulic Investigation of Triangular Plan Form Vertical Drops

Hydraulic Investigation of Triangular Plan Form Vertical Drops

Determination of flow characteristics over sharp-crested triangular plan form weirs using numerical simulation

ABSTRACT Triangular plan form weirs are one type of long-crested weirs. Therefore, they can pass more discharge capacity than weirs at the given channel width. This study aims to investigate the effects of different number of teeth (3, 4, and 5 teeth), angle of the weir tip (90, 60, 120, and 150 degrees), and the amount of different discharges (0.009–0.0063 m3/s) of sharp-crested triangular plan form weirs on the hydraulic parameters by using the Finite Volume Method (FVM). It was found that, increasing the effective length of the crest, increases the discharge coefficient up to 95% in the case with 5 teeth (L/B = 4.14 and h/W = 0.128), 45% in the case with 4 teeth (L/B = 3.71 and h/W = 0.168) and 39% for 3 teeth (L/B = 3.28 and h/W = 0.188) compared to the simple triangular plan weir (without teeth). Also, Results indicated that the discharge coefficient has an inverse relationship with the h/w ratio. In contrast, the investigations showed that the velocity in the flow jet is affected by the effective length of the triangular plan crest, and the increase in the effective length results in a decrease in the average velocity of the flow jet. So that these disturbances caused the highest dissipation of energy to occur in the triangular plan crest with 5 teeth (27% compared to the upstream section (Section 1) and 37% compared to the downstream section (Section 2)).

Tectonic geomorphology and Quaternary fault slip rates in the Tsambagarav Massif, Mongolian Altai

AbstractThe NNW‐striking Mongolian Altai is a Late Cenozoic dextral strike–slip deformation belt affected by the far‐field stress caused by the collision between India and Eurasia. The Tsambagarav Massif is bounded by faults, has a triangular plan shape, and attains the highest elevation of the belt. This massif is adjacent to the central segment of the Hovd fault, which is the largest fault in the Mongolian Altai. Here, we use 10Be surface exposure dating, radiocarbon dating, and paleoseismic trenching to reveal deformation patterns and Quaternary slip rates for two range‐bounding faults: the Tsambagarav dextral reverse fault and the Lower thrust fault. The Lower thrust exhibits thrusting motion along the low‐angle structural fabric of the basement rock and cuts Quaternary alluvial fan deposits, vertically offsetting their surfaces by 3.9–5.1 m, with fault scarps extending several kilometres along‐strike. The Tsambagarav dextral reverse fault is characterized by strike–slip motion along the high‐angle structural fabric of basement rock. Various surface deformation features indicate recent dextral strike–slip, including displacements of Late Quaternary moraine by ~50 m. Dividing the measured displacements by 10Be surface exposure ages of alluvial fan surfaces (for the Lower thrust) and moraine (for the Tsambagarav dextral reverse fault) gives a reverse slip rate of 0.3–1.7 mm/yr for the Lower thrust and a horizontal slip rate of 1.7–2.6 mm/yr for the dextral reverse fault. Radiocarbon ages of animal bones in a pond deposit accumulated along an associated tensional crack indicate that the last earthquake that caused a surface rupture occurred between 1924 and 1708 cal yr BP. Our study suggests that strain partitioning has occurred on the faults of the Tsambagarav Massif.

Comparison of aerodynamic coefficients of tall tapered triangular building modified with golden spiral in plan

Better designs are mostly better geometries. Geometric shape modifications in buildings can greatly improve the aerodynamic performance as well as add to the aesthetics of the buildings. The present study involves a comparison of aerodynamic coefficients of a triangular building with slight changes in the plan. Force and pressure coefficients are compared among the buildings with tapering regular triangle in plan, tapering triangular plan modified with rounded corners, and tapering triangular plan modified with Golden spiral geometry in all possible wind attack directions. Numerical method was used with the help of ANSYS CFX and the k-epsilon turbulence model was used in this simulation. Pressure coefficients are compared locally and the problem of huge suction due to rounded corner modification can be reduced to a considerable extent by the Golden spiral geometry. The Drag coefficients are compared and the golden spiral has the least values in all possible directions of wind attack.

The energy dissipation of flow over the labyrinth weirs

In this study, the energy dissipation of flow over the triangular and trapezoidal labyrinth weirs with one and two key cycles was investigated. The magnification ratios (MR) of models were 1.57, 2.57, 3.57, and 4.57. Results declared that the labyrinth weirs can dissipate the energy of flow between 85% and 70% considering the range of the relative head (ho/P) between 0.10 and 1.0. The lowest efficiency of labyrinth weirs concerning energy dissipation occurs when the ho/P is about 0.25. For values less than 0.60 of ho/P, by increasing MR, the performance of models is decreased. For values less than 0.30 of ho/P, the performance of the trapezoidal plan crest is about 10 percent lower than the crest with a triangular plan. For values greater than 0.30 of ho/P, the performances of labyrinth weir models are identical and are about 75%.

An ISaDE algorithm combined with support vector regression for estimating discharge coefficient of W-planform weirs

AbstractVarious shapes of weirs, such as rectangular, trapezoidal, circular, and triangular plan forms, are used to adjust and measure the flow rate in irrigation networks. The discharge coefficient (Cd) of weirs, as the key hydraulic parameter, involves the combined effects of the geometric and hydraulic parameters. It is used to compute the flow rate over the weirs. For this purpose, a hybrid ISaDE-SVR method is proposed as a hybrid model to estimate the Cd of sharp-crested W-planform weirs. ISaDE is a high-performance algorithm among other optimization algorithms in estimating the nonlinear parameters in different phenomena. The ISaDE algorithm is used to improve the performance of SVR by finding optimal values for the SVR's parameters. To test and validate the proposed model, the experimental datasets of Kumar et al. and Ghodsian were utilized. Six different input scenarios are presented to estimate the Cd. Based on the modeling results, the proposed hybrid method estimates the Cd in terms of H/P, Lw/Wmc, and Lc/Wc. For the superior method, R2, RMSE, MAPE, and δ are obtained as 0.982, 0.006, 0.612, and 0.843, respectively. The amount of improvement in comparison with GMDH, ANFIS and SVR is 3.6%, 1.2% and 1.5% in terms of R2.

Development of ANN model for discharge prediction and optimal design of sharp-crested triangular plan form weir for maximum discharge using linked ANN–optimization model

Abstract Triangular plan form weirs are advantageous over a normal weir in two ways. Within the limited channel width, use of such a weir increases the crest length and hence for a given head, increases the discharge and for a given discharge, reduces the head in comparison with a normal weir. In a previous study, researchers proposed an empirical equation to compute the discharge coefficient of a triangular plan form weir. The prediction error on the discharge coefficient was ±7% from the line of agreement. In the present study, an ANN model has been utilized to train randomly selected 70% data, with 15% tested and validation made for the remaining 15% data. The model predicts the discharge coefficient with a prediction error in the range of ±2.5% from the line of agreement, thereby decreasing the prediction error in Cd by 64%. Also, the sensitivity analysis of the developed ANN model has been performed for all the parameters (weir height, skew weir length and flow depth) involved in the study and the weir height was found to be the most sensitive parameter. Furthermore, the linked ANN–optimization model has been developed to find the optimal values of design parameters of a triangular plan form weir for maximum discharge.

Experimental Verification And Review Performance of The Modified Triangular Plan Form Weir

Weirs are discharge measurement structures have different geometrical shapes. The performances of the modified triangular plan form weirs were studied under free-flow condition. Three groups of weirs were tested experimentally. The first group has a flat top; the second has one slope and the third has two slopes. Each group has three vertex angles (60o, 90oand 120o) with constant height. The hydraulicperformances of weirs are based on the ability to pass the discharge for certain head flow and on the value of the coefficient of discharge. The values of discharge and the coefficient were compared with earlier studies being carried on conventional normal weir, broad crest, triangular plan-form and different labyrinth weirs. All the groups show better performance than conventional shaped and broad weir. The magnification of the actual discharge to the discharge of broad crested weir is more than one and the best one is the first in the third group, while the vertex angle is (60o) for the second and third group and (120o)for the first. The performance of the third group is better than rectangular labyrinth weirs, and it is compatible with the triangular labyrinth. The discharge coefficient decreases with the increase of relative value of the head to the height of weir except for the first group. Equations for predicting coefficient of discharge are proposed within the limitations of this test.

The Effect of Geometric Parameters of the Antivortex on a Triangular Labyrinth Side Weir

Side weirs are important structural measures extensively used, for instance, for regulating water levels in rivers and canals. If the length of the opening is limited, the amount of water diverted out of the channel and the effective length can be increased by applying a labyrinth side weir. The present study deals with numerical simulations regarding the hydraulic performance of a labyrinth side weir with a triangular plan in single-cycle mode. Specifically, six different types of antivortexes embedded inside it and in various hydraulic conditions at different Froude numbers are analyzed. The antivortexes are studied using two groups, permeable and impermeable, with three different heights: 0.5 P, 0.75 P, and 1 P (P: Weir height). The comparison of the simulated water surface profiles with laboratory results shows that the numerical model is able to capture the flow characteristics on the labyrinth side weir. The use of an antivortex in a triangular labyrinth side weir reduces the secondary flows due to the interaction with the transverse vortexes of the vertical axis and increases the discharge capacity by 11%. Antivortexes in a permeable state outperform those in an impermeable state; the discharge coefficient in the permeable state increases up to 3% with respect to the impermeable state. Finally, based on an examination of the best type of antivortex, taking into account shape, permeability, and height, the discharge coefficient increases to 13.4% compared to a conventional labyrinth side weir.

Bearing Capacity and Settlement Response of Ordinary and Geosynthetic Encased Granular Columns in Soft Clay Soils: Analysis and Design Charts

This paper discusses the bearing capacity and settlement response of granular columns with and without geosynthetic encasement using the currently available design procedure. The design procedure is modified to include the influence of the geosynthetic encasement. The key parameters influencing the load bearing capacity and settlement are studied through comprehensive parametric analyses. The results portray the advantage of geosynthetic encased granular columns in enhancing the bearing capacity and reducing the settlements compared to granular columns without encasement. Different installation patterns of granular columns were considered in this investigation. The maximum bearing capacity improvement and settlement reduction are observed with granular columns installed in triangular plan arrangement. The hexagonal pattern results in the lowest area replacement ratio and also the lowest improvement factors. It is shown that with geosynthetic encasement, the performance with hexagonal pattern could be improved to match with other more efficient patterns like square and triangular. Some selected results are validated through detailed finite element results. A quick assessment of the settlement improvement with geosynthetic encapsulated granular columns is possible with the design charts presented.

An Experimental Investigation into the Effect of Curve Radius on the Discharge Coefficient in Curved-Linear and Curved-Labyrinth Weirs with a Triangular Plan

An Experimental Investigation into the Effect of Curve Radius on the Discharge Coefficient in Curved-Linear and Curved-Labyrinth Weirs with a Triangular Plan

Study on the Effect of the Position of X-bracing Arrangement in the Steel Structures with a Triangular Plan

Study on the Effect of the Position of X-bracing Arrangement in the Steel Structures with a Triangular Plan

Flow Characteristics of Triangular Plan Form Weir

Weirs are used for discharge measurement and flow diversion in the open channels. However, modified weirs such as plan form weirs, Labyrinth weir, oblique weir and piano key weir, etc. having larger crest length compared to normal weir having same lateral space assist in enhancing discharging capacity for a given upstream head, without creating much afflux. An experimental study was carried out to understand the effect of the geometry of a triangular plan form weir on discharge coefficient under free and submerged flow conditions. In this paper attempts are made to investigate working of triangular plan form weir of vertex angle 45° with three heights 10, 20 and 30 cm under free and submerged flow conditions. The discharge coefficients were calculated under free & submerged flow conditions and the results were compared with normal weirs as well. Further, triangular plan form weir is quite simple device/geometry and easy to install & quite useful for discharge measurement in open channels.

Unified discharge coefficient formula for free and submerged triangular labyrinth weirs

The flow through a triangular plan labyrinth weir is studied for both free and submerged flow conditions experimentally and theoretically. The free flow condition is studied using a new experimental data set collected in this study. For the submerged flow condition, the threshold between free and submerged flow regimes is studied experimentally. Then Buckingham analysis is employed to determine the submerged head-discharge formula of the triangular plan labyrinth weir. Finally, a step by step calibration method is proposed to find the unified discharge coefficient. The proposed discharge coefficient can be used for both free and submerged flow conditions continuously and within the transition zone.

Hydraulic Performance of Circular Crested Triangular Plan Form Weirs

Triangular labyrinth weirs are nonlinear weirs used to control and pass the required discharge with low afflux in case of limited width saving the upstream countryside and costly lands from submergence. In this paper, the hydraulic performance of circular crested triangular plan form weirs under free flow conditions is experimentally studied. In this regard, twenty-seven weir models have been fabricated and tested in a laboratory flume. These models had different vertex angles (\(\theta = 45^{\circ }\), \(60^{\circ }\) and \(75^{\circ }\)), different weir heights (\({P} = 15\), 20 and 25 cm) and different crest diameters (\({D} = 2.54\), 4 and 5 cm). The experimental results of all models showed that the variation of discharge coefficient (\({C}_{\mathrm{d}}\)) with relative head above crest (h/P) for the different values of \(\theta \), P and D was a simple power equation. It was observed that the values of \({C}_{\mathrm{d}}\) decreased with the increase in h/P values for all models. An empirical power equation was obtained for the estimation of \({C}_{\mathrm{d}}\) in terms of \(\theta \), h/P and h/D. The values of discharge magnification (\({Q}_{{\mathrm{TC}}}/{Q}_{{\mathrm{NS}}}\)) decreased with the increase in h/P values. Weirs of small vertex angle, low height and small crest diameter gave high values of discharge magnification (better performance). The best weir performance was found for a weir of \(\theta = 45^{\circ }\), \({P} = 15\,\hbox {cm}\) and \({D} = 2.54\,\hbox {cm}\) (\({D/P} = 0.17\)) within the limitations of this study.

Experimental and numerical evaluation of discharge capacity of sharp-crested triangular plan form weirs

Experimental and numerical evaluation of discharge capacity of sharp-crested triangular plan form weirs

Experimental and numerical evaluation of discharge capacity of sharp-crested triangular plan form weirs

Weirs are those structures used extensively for flood passage, flow measurement, flow deviation and controlling the water level in dams, rivers and open channels. In this study, the numerical model was simulated using flow-3D software and the results from experimental and numerical model were compared. Investigations have shown that the results of RNG turbulence model are better compared to k-e and LES models. Then, to model the turbulence, and to determine the location of free-surface profile, RNG model and VOF method were used respectively. Experimental results show proper coordination with estimated results of numerical model. For similar low values of h/p, the performance of 30 degree sharp crested triangular plan form weir for discharging of overflow was more suitable than other sharp-crested triangular plan form weirs.

Numerical Modeling of Sharp-Crested Triangular Plan Form Weirs Using FLUENT

Weirs are hydraulic structures used for measuring flow rate. Triangular labyrinth weir is a kind of non-linear weirs which are used to control free flow passing over weirs in low width. Accordingly, the present paper attempted to investigate the characteristics of flow in triangular labyrinth weirs through FLUENT Software. In this regard, using GAMBIT Model, geometrical and grid generation conditions of flow was created for flow field solution. Using numerical model of Fluent, boundary conditions and flow field conditions were implemented for the model. Meshing conditions is for about 300 thousands cells with at most about 11% error. In the next test, simulation error is decreased about 30% through minimizing the size of computational cells and flow field solution for 580 meshes and the maximum depth simulation error reaches to 8%. Re-decreasing the cells’ size and the limited number of about 1 million computational cells causes that simulation error approaches to 7%.Through more careful computational cells selection and given to hardware limitations during simulation time, about 580 thousands cells with average size of 20 mm were selected. It is due to the fact that smaller selection leads to the increase of flow field modeling time up to 2 times more than time. Numerical model of FLUENT is highly able to simulate flow field in labyrinth weirs.