Estimation of the Local Scour from a Cylindrical Bridge Pier Using a Compilation Wavelet Model and Artificial Neural Network

In the present study, an artificial neural network and its combination with wavelet theory are used as the computational tool to predict the depth of local scouring from the bridge pier. The five variables measured are the pier diameter of the bridge, the critical and the average velocities, the average diameter of the bed aggregates, and the flow depth. In this study, the neural wavelet method is used as a preprocessor. The data was passed through the wavelet filter and then passed to the artificial neural network. Among the various wavelet functions used for preprocessing, the dmey function results in the highest correlation coefficient and the lowest RMSE and is more efficient than other functions. In the wavelet-neural network compilation method, the neural network activator function was replaced by different wavelet functions. The results show that the neural network method with the Polywog4 wavelet activator function with a correlation coefficient of 87% is an improvement of 8.75% compared to the normal neural network model. By performing data filtering by wavelet and using the resulting coefficients in the neural network, the resulting correlation coefficient is 82%, only a 2.5% improvement compared to the normal neural network. By analyzing the results obtained from neural network methods, the wavelet-neural network predicted errors compared to experimental observations were 8.26, 1.56, and 1.24%, respectively. According to the evaluation criteria, combination of the best effective hydraulic parameters, the combination of wavelet function and neural network, and the number of neural network neurons achieved the best results

Static strength of collar plate reinforced tubular T/Y-joints under brace compressive loading

In the present paper, the static strength of steel collar plate reinforced tubular T/Y-joints is numerically investigated. A finite element (FE) model was developed and the results were verified against the experimental data. Afterwards, a set of 168 FE models of collar plate reinforced T/Y-joints was generated and analyzed under axially compressive loads. The effect of plate size and joint geometry on the ultimate strength and failure mechanism of the joints were investigated through a parametric study. Results showed that the ultimate strength of a collar plate reinforced T/Y-joint can be up to 270% of the strength of the corresponding unreinforced joint. Despite this significant difference between the static strength of unreinforced and collar plate reinforced T/Y-joints, studies on this type of reinforced joints have been limited to very few T-joint tests. Also, no design equation is available to determine the ultimate strength of T/Y-joints reinforced with collar plates. Hence, after the parametric study, a new equation is proposed, through nonlinear regression analysis, for determining the ultimate strength of collar plate reinforced T/Y-joints under axially compressive loads

Static performance of doubler plate reinforced tubular T/Y-joints subjected to brace tension

In the present study, data extracted from the finite element analysis of 210 models, which were verified against the data available from eight experimental tests, were used to investigate the geometrical effect on the ultimate strength, initial stiffness, and failure modes in doubler plate reinforced tubular T/Y under axially tensile load. Results indicated that the doubler plate can significantly increase the initial stiffness, ultimate capacity, and considerably improve failure modes. Also, the reinforcing effect of the doubler plate thickness and doubler plate length on the ultimate capacity becomes more remarkable when one of these parameters is big. Despite this significant difference between the static capacity of unreinforced and doubler plate reinforced T- and Y-joints subjected to brace tension, studies on these types of reinforced joints have been confined to very few T-joint tests. Moreover, no design formula is available to compute the ultimate capacity of doubler plate reinforced T/Y-joints. For these reasons, geometrically parametric investigation was followed by a set of nonlinear regression analyses to propose an ultimate capacity parametric formula for the static analyses of doubler plate reinforced tubular T/Y-joints under axially tensile load

Factorial Mixture Design for Properties Optimization and Modeling of Concrete Composites Incorporated with Acetates as Admixtures

Nowadays, admixtures are used with the aim to provide strength and durability to concrete with less water use. New and low-cost admixtures gained a large amount of consideration to mitigate the problems associated with concrete’s durability and service life without upsetting its strength properties. The current work investigates the effect of three types of acetates on the workability, density, and compressive strength of concrete, which is used in structures of the Iraqi ports that suffer from corrosion damages and deterioration owing to the aggressive marine environments. Potassium acetate (KA), calcium acetate (CaA), and ethyl acetate (EA) are incorporated with different doses (1.38–5.6 wt.% of cement) in concrete mixtures using different water/cement ratios (0.48–0.54) based on an espoused central composite experimental design. The experimental results confirmed that the average workability increased with increasing the acetate dose, particularly with CaA. The density and compressive strength of 28 days of water-cured mixtures increased with increasing acetate dose following the order: Ca > K > Ethyl acetate and decreased with increasing w/c ratio. The high rise in compressive strength and workability linked to control mixtures was 30.8% and 77.3% as well as 15.7% and 64.3% for the mixtures incorporated with 5.6 wt.% CaA and KA, respectively. While it was 14.2% and 58.3% for the mixtures incorporated with 3.5 wt.% EA. RSM was employed to optimize and model the design and hardened properties of concrete mixtures. ANOVA results predicted the same trend, which was obtained from the experimental results. The mathematical models were valued with high-regression coefficients. The highest compressive strength of 42.68 MPa has been achieved for a concrete mixture of 0.48 w/c ratio by the incorporation of 5.1 wt.% CaA through a model with R2 96.97%. The relatively low-cost acetate admixtures, particularly CaA, seemed promising for the fabrication of concrete with outstanding properties

Structural behavior of tubular T/Y-joints with collar plate under static in-plane bending

This paper investigates the static strength of collar plate reinforced tubular T/Y-joints subjected to in-plane bending (IPB) load. At the first step, a finite element (FE) model was developed and validated against the data available from 12 experimental tests. Afterwards, 210 FE models were generated and analyzed to evaluate the effect of joint geometry and collar plate size on the ultimate strength and failure modes of T/Y-joints reinforced with collar plates subjected to IPB load. Results show that the collar plate reinforcement method can significantly increase the ultimate strength and improve the failure mechanisms of tubular T/Y-joints under in-IPB load. Despite the considerable effect of the collar plate on the static strength and in spite of the frequent usage of CHS T/Y joints in offshore jacket-type platform, the ultimate strength and failure modes in collar plate reinforced T/Y-joints subjected to IPB load have not been investigated so far and no design equation is available to determine the ultimate capacity of IPB-loaded joints of this type. Therefore, after the parametric investigation, a new formula is proposed, through nonlinear regression analysis, for determining the ultimate strength of T/Y-joints reinforced with collar plate subjected to IPB load

Seismic responses of an offshore jacket-type platform incorporated with tuned liquid dampers

In this article, the efficiency of tuned liquid damper in controlling the dynamic responses of offshore jacket-type platforms under earthquake excitation is investigated. This type of dampers consisting of a number of fluid-containing tanks can be installed on the topside of the platform. Hydrodynamic loads induced by the sloshing of the fluid inside the tank act as resistant forces against the vibration and can thus control the structural response. In this research, using finite element–based software package ANSYS, a jacket-type platform having dimensions appropriate for the Persian Gulf climate (case study: SPD1 platform) was modeled and then dynamically analyzed by the modal and time-history approaches subjected to the records of El Centro, Kobe, and Tabas earthquakes. The tuned liquid dampers were optimally designed and after the verification of FE results, the dynamic responses of the jacket-type platforms with and without the tuned liquid damper system were compared

Static strength of doubler plate reinforced tubular T/Y-joints subjected to brace compressive loading: Study of geometrical effects and parametric formulation

In this study, the ultimate strength, initial stiffness, and failure mechanisms of tubular T/Y-joints reinforced with doubler plate under axially compressive load are numerically investigated. At the first step, a finite element (FE) model was developed and verified against the data available from eight experimental tests. At the next step, 210 FE models were generated and analyzed to evaluate the effect of joint geometry and doubler plate size on the static strength of doubler plate reinforced T/Y-joints under axially compressive load. Results showed that the ultimate strength of a doubler plate reinforced T/Y-joint can be up to 295% of the strength of the corresponding unreinforced joint. Also, doubler plate reinforcement method can considerably increase initial stiffness and improve the failure modes of tubular T/Y-joints subjected to axially compressive load. Afterwards, the deformed shapes of doubler plate and collar plate reinforced T- and Y-joints are compared. Despite the considerable effect of the doubler plate on the static strength, its feasible application during the joint fabrication, and the frequent usage of CHS T/Y joints in offshore jacket-type platforms, the ultimate strength, initial stiffness, and failure modes in doubler plate reinforced Y-joints under axially compressive load have not been studied. Also, so far no design equation is available to determine the ultimate strength of T- and Y-joints reinforced with doubler plate under the axially compressive load. Hence, after the parametric investigation, a new formula is derived, through nonlinear regression analysis, to determine the ultimate strength in such case