Steel Pipe Diameter Research Articles

A Study on the Ultimate Span of a Concrete-Filled Steel Tube Arch Bridge

In order to study the ultimate span of a concrete-filled steel tube (CFST) arch bridge, taking the structural strength, stiffness, and stability as the limiting conditions, the finite element analysis method is adopted to carry out research on the influence law of a single parameter of the pipe diameter, wall thickness, and cross-section height on the ultimate span of the arch axial shape. The result is used as a sample point to determine the ultimate span of the CFST arch bridge under multifactor coupling based on the response surface method. The finite element method is used to check the strength, stiffness, stability, number of segments and maximum lifting weight, steel content rate, and steel pipe concrete constraint effect coefficient of the CFST arch bridge under the ultimate span diameter. The results show that, when analyzed using a single parameter, the ultimate span diameter of the CFST arch bridge increases with the increase in the steel pipe diameter and the cross-section height, and then decreases. Moreover, it increases with the increase in the wall thickness of the steel pipe, and the CFST arch bridge reaches the ultimate span with the increase in the steel pipe wall thickness. When the pipe diameter is 1.38 m, the CFST arch bridge reaches the ultimate span; according to a multi-parameter coupling analysis, when the pipe diameter is 1.49 m, wall thickness is 37 mm, and cross-section height is 17 m, the CFST arch bridge reaches the ultimate span of 821 m, which meets all of the limiting conditions, and, at this point, the arch axial coefficient is 1.2. The results of the finite element calculation show that the structural strength, prior to the stiffness, stability, and other limitations, just reaches the critical value of the limiting conditions.

ANALYSIS AND OPTIMIZATION OF WIND RESISTANCE PARAMETERS FOR LATTICE-TYPE HIGH-MODULUS SUPPORTS BASED ON THE OPTIMAL CRITERIA METHOD

Lattice high-molded support can generally be used for cast-in-place support for bridges, but for more than 50 meters of lattice high support, due to the wind, load and other factors, due to the support length and slenderness of the relatively large, relatively light and flexible structure and other characteristics of the role of the wind load is very sensitive. When the lattice high-molded stent construction is used in the typhoon area, it is easy to be damaged by the typhoon, and the structural design of the lattice high-molded stent and the construction of that technology are facing great challenges. In this paper, based on the new construction of a special bridge in Fujian, finite element analysis of four-legged and six-legged lattice bracing is carried out by ANSYS, and the effects of steel pipe diameter, number of columns, longitudinal and transversal spacing of bracing, and diagonal bracing structural parameters on structural performance are analyzed by using the coefficients of buckling stability and the coefficients of critical loading. The results of the study show that the main design variable for displacement sensitivity is the diameter of vertical rod; the main design variable for stress sensitivity is the diameter of diagonal rod; the main design variable for overall stability sensitivity is the diameter of diagonal rod; and the main design variable for overall stability sensitivity of total volume is the diameter of diagonal rod. And the optimal wind resistance parameters are: 4 lattice high-braced columns are selected, the section length should be controlled within 15m, and the total height should not be more than 70m, and the spacing of the columns is controlled between 7m and 8m. This study proposes a set of optimized design process method for wind-resistant lattice structure under the constraints of stiffness, strength and critical load factor, which improves the economy and ensures the reasonableness of the design, and can be used for the design of high-modular lattice bracket in typhoon area.

Loading capacity of welded hollow spherical joints strengthened by cone member

The Welded Hollow Sphere Joint (WHSJ) is frequently employed as a connection form in spatial grid structures. Structures don't retire immediately upon damage, necessitating reinforcement. However, effective solutions for reinforcing WHSJs still have shortcomings in practical engineering applications. Given this research context, a reinforcement scheme for WHSJs is proposed. Feasibility is confirmed through numerical simulation, showing that this reinforcement method is applicable to WHSJs with initial loads, enhancing their mechanical performance without being influenced by the initial loads. The study also initially uncovers the patterns of load-bearing capacity variation with geometric dimensions. Subsequently, an Artificial Neural Network (ANN) is used to predict compressive load-bearing capacity. It utilizes input variables such as sphere diameter (Ds), steel pipe diameter (Dp), reinforcement cone base diameter (Dt), sphere thickness (Ts), steel pipe thickness (Tp), cone thickness (Tt), and cone base angle (θ), with the output being the compressive load-bearing capacity of the welded hollow sphere joint post-reinforcement. Prediction errors are confined to within 10%. Using the Garson algorithm, the sensitivity analysis reveals that steel pipe thickness (Tp) and sphere thickness (Ts) play relatively significant roles in the prediction process.

Influence of welding residual stress on bending resistance of hollow spherical joints

Welded hollow spherical joints are widely used in large-span spatial structures because of their simple organization and convenient construction. However, in the sphere-pipe connection welds of the joints, welding residual stress is generated, which will adversely affect the mechanical properties of the joints and the overall structure. In this paper, the parametric model of welded hollow spherical joints was established by employing the geometric configuration dimensions of those joints frequently used in engineering. Through the combination of experimental research and numerical simulation, the welding residual stress of welded hollow spherical joints and its impact on joints' bending resistance were studied. First of all, based on the distribution pattern of the stress, bending test of the joints was carried out and revealed the influence of welding residual stress on the bending stiffness and ultimate bending capacity of the joints; Then, through the results of experimental analysis and finite element calculation, and with parametric analysis, the impact of welding residual stress on joints' bending resistance was clarified with the variation of parameters such as the hollow sphere diameter D, wall thickness t and the connecting steel pipe diameter d. It is shown that welding residual stress has a great impact on joints' bending stiffness, with a reduction more than 10%, while it doesn't affect their ultimate bending capacity much, with an influence no more than 5%. In addition, as D increases, t, and d decrease, its impact on the bending resistance rises.

Design and optimization of secant pipe roofing structure applied in subway stations

A secant pipe roofing (SPR) structure is a novel pipe roofing structure with considerable potential as a supporting structure for subway stations, whose structural system affects the bending loading conditions during construction. Therefore, it is essential to conduct further flexural research. However, minimal research has focused on the flexural behavior of SPR structures; in addition, the influence of parameters remains unclear and optimal parameter combinations remain lacking. Hence, the main purpose of this study was to investigate the flexural performance of the SPR structure and establish a finite element (FE) model with precise material constitutive models to optimize the parameters. First, the flexural behavior of the SPR structure was investigated using flexural tests. During the entire loading process, all specimens exhibited ductility, with the specimens' three stress phases and failure mechanisms discussed and clarified based on the experimental results. Subsequently, 16 sets of FE models were built to study the effects of the parameters on the ultimate capacity, deformation, and cost of the SPR structure. Furthermore, the calculations of the ultimate capacity and SPR flexural stiffness obtained using the proposed formulas were consistent with the experimental results and numerical simulations. Finally, a combination of different parameters was optimized using the fuzzy mathematical theory. The optimal parameter combination is a steel pipe diameter: steel pipe thickness: steel bar diameter: adjacent steel pipes’ overlapping length is 1:0.03:0.04:0.37. These results are expected to provide a reliable reference for the design and application of SPR structures.

Theoretical Analysis on the Effectiveness of Pipe Roofs in Shallow Tunnels

When a pipe roof is used as a pre-support for the surrounding rock in a shallowly buried tunnel, accurate prediction of the support effectiveness of the pipe roof is important in order to ensure the rationality of the pipe roof structure design. Based on analysis of pipe roof pre-support effects, considering the construction time of pipe roof structures and the interaction mechanisms between the steel pipes of the pipe roof and the surrounding rock, we establish a calculation model of the surrounding rock pressure acting on each steel pipe of the pipe roof on the semi-circular pre-support boundary. Through comparison and analysis with the measured results, we demonstrate that the calculation model for surrounding rock pressure and the calculation model for stress and deformation of the pipe roof are reasonable. According to the deformation coordination conditions between the steel pipe of the pipe roof and the surrounding rock on the pre-support boundary and alongside the Peck formula, we establish a theoretical analysis method for pipe roof pre-support effectiveness based on the indexes of the ground loss rate, settlement trough width, and maximum ground surface settlement, thereby realizing a quantitative evaluation of pipe-roof pre-support effectiveness. At the same time, the effects of steel pipe diameter, circumferential spacing, and excavation footage length on the pre-support effectiveness of the pipe roof are analyzed. The conclusions can be used as a basis for the design and optimization of pipe roofs and as a guide for the application of pipe roofs.

Analysis of the influence of geometrical parameters of circular steel pipe with flange plate on the jacking force

Jacking force is one of the important safety indicators during pipe jacking construction. Existing models for calculating jacking force are widely used in the calculation of jacking force for pipe with regular cross-sections. In this paper, considering pipe-soil interaction, the cross-sectional characteristics and the distribution characteristics between pipe and soil, the calculation equations for the jacking force of circular steel pipe with flange plate were proposed based on the pressure arch theory. The proposed equations were applied to calculate the jacking force for the Olympic Sports Center Subway Station of Line 9 in Shenyang, China, and the results were compared with the field monitoring data to predict the accurate jacking force. Based on the proposed equations, the influences of the flange plate position and steel pipe diameter on earth pressure around the pipe were analyzed. The functional relationship between the earth pressure and the position of flange plate or the pipe diameter was obtained, which provides design basis and theoretical guidance for engineering practice.

Pipe Sizing of District Cooling Distribution Network Using Implicit Colebrook-White Equation

An implicit solution of Colebrook-White equation was used in calculating the friction factor for commercial steel pipes using Newton-Raphson method with Reynolds number ranging from 4.0 × 103to 1.3 × 107. Initial value for iterative friction factor estimation was based on expanded form of Colebrook-White equation for larger values of Reynolds number with tolerance value of 1.0 × 10-8. Numerical results were compared with known explicit solutions and iterative procedure proposed by Lester in which, their mean difference, root-mean square deviation, mean relative error and correlation coefficient were evaluated. Correlation coefficients equal to unity and overall mean relative error of 4.821 × 10-8were achieved for all fifteen (15) pipe cases with nominal diameters ranging from 100 mm to 1,500 mm when compared with iterative solution suggested by Lester. Student’s t-test for paired data was also used which yielded a calculated t-value of -5.406 × 10-4. Combining the piping network design criteria with the logical structure of friction factor calculation determines the pipe size of distribution network and defines the boundaries of chilled-water velocities at different pressure drop limits as a function of commercial steel pipe diameter according to ANSI B36.1.

Study and application of a new type of foamed concrete wall in coal mines

A new type of airtight wall with the combination of foamed concrete and pier support was designed in this study. Based on the theories and models related to the foamed concrete and blasting shock load, using the numerical analysis method, this study obtains the new material’s mechanical and destruction laws through analyzing its reaction to different conditions of load (mining and shock waves), airtight wall thickness (1.2, 1.5, 1.8, 2.1 m) and steel pipe diameters (400, 450, 500 and 600 mm). The results show that: ① foamed concrete can have very good suspension, and the pier column support is the main carrier of roof pressure; ② the damaged area of foamed concrete decreases as the foamed concrete thickness increases. Under impact loading, the thickness of the foamed concrete wall plays a more obvious role in retaining its integrity; ③ under the same mining pressure, the damage area increases as the steel pipe diameter increases; ④ with additional mining stress increase, under whether static load or impact load, the stress on the foamed concrete and steel pipe will also increase gradually, therefore the actual airtight wall design will need to be based on specific circumstances in steel stress.

PENETAPAN RUTE DAN PERHITUNGAN KEEKONOMIAN PIPA TRANSMISI GAS MUARA BEKASI – MUARA TAWAR MELALUI JALUR LEPAS PANTAI

Muara Bekasi – Muara Tawar Offshore Transmission Pipeline Routing and Economic Analysis. Power plant Muara Tawar will substitute the need of oil fuel to gas as form of economizing and energy conservation. The nearest supply point to fulfill natural gas needed on Muara Bekasi. So that Power Plant Company needed to develop gas pipeline infrastructure to joining the point.The purpose of this study is to create a system of gas transmission pipeline from gas supply point at Muara Bekasi to Power Plant Muara Tawar trough to offshore area. Design of gas transmission pipeline is started with technical data collection and supply-demand analyzing, continued with data analysis, rute construction and result of condition operation. The standard design of this design is DnV 2000. Gas demand in Power Plant Muara Tawar is 400 MMSCFD. From secondary data had been obtained total length of alternative route 3.7 km. Carbon Steel pipe diameter which had been used 22 inch nominal diameter. Gas supply pressure is 350 psig with pressure of demand point is setted on 500 psig. On pipeline system design the preesure before put in to compressor is around 321.7 psig. The design on bottom stability factor is the main concern. From the design calculation the total minimum pipe weight is 793.16 ton, whereas the design around 932.6 ton. Therefore, the pipe will be stable on bottom of sea.

A simple correlation for estimation of economic thickness of thermal insulation for process piping and equipment

Abstract Where the sole object of applying insulation to a portion of plant is to achieve the minimum total cost during a specific period (evaluation period), the appropriate thickness is usually termed as the economic thickness. The principle is to find at what thickness further expenditure on insulation would not be justified by the additional financial saving on heat to be anticipated during the evaluation period. Although an increase in the amount of insulation applied will raise the initial installed cost, but it will reduce the rate of heat loss through the insulation. Therefore it is necessary to reduce the total cost during the evaluation period. In this work, simple-to-use correlation, employing basic algebraic equations which are simpler than current available models involving a large number of parameters, requiring more complicated and longer computations, is formulated to arrive at the economic thickness of thermal insulation suitable for process piping and equipment. The correlation is as a function of steel pipe diameter and thermal conductivity of insulation for surface temperatures at 100 °C, 300 °C, 500 °C and 700 °C. A simple interpolation formula generalizes this correlation for wide range of surface temperatures. The proposed correlation covers pipeline diameter and surface temperature up to 0.5 m and 700 °C, respectively. The average absolute deviation percent of proposed correlation for estimating the economic thickness of the thermal insulator is 2% demonstrating the excellent performance of proposed simple correlation.