Circular Steel Pipe Research Articles

Evaluation of Compression Performance of APM Aluminum Foam-Polymer Filled Pipes Prepared via Different Epoxy Resin Bonding Processes

The composite structurehttp://mts.hindawi.com/update/) in our Manuscript Tracking System and after you have logged in click on the ORCID link at the top of the page. This link will take you to the ORCID website where you will be able to create an account for yourself. Once you have done so, your new ORCID will be saved in our Manuscript Tracking System automatically."?> with aluminum foam not only has the strength and toughness of the dense material but also reduces the weight of the component and increases specific deformation energy absorption performance. In this paper, advanced pore morphology (APM) foam elements are combined with thin-walled circular steel pipes by epoxy-bonding and epoxy foam-bonding processes to prepare composite circular pipes. The direct epoxy-bonding process using epoxy resin refers to coating the surface of APM spheres, whereas the epoxy foam-bonding process involves the mixing of the epoxy resin with the epoxy foaming agent and then coating the surface of APM spheres with this mixed epoxy resin. The compression performances and energy absorption performances were analyzed by quasistatic compression tests. Results indicate that the different bonding modes change the deformation mode of the specimen under compression. The epoxy foam-bonding APM composite pipe has a higher compression load level than the epoxy-bonding APM filled pipe. The epoxy foam-bonding APM composite pipe is superior to the epoxy-bonding APM composite and thin-wall hollow pipe. Hence, the combination of foaming and bonding of epoxy can be used as a new filling process for APM fillers.

Calculating Jacking Forces for Circular Pipes with Welding Flange Slabs from a Combined Theory and Case Study

Recently, the Steel Tube Slab (STS) curtain method has been successfully used in the construction of ultra-shallow metro stations in modern urban areas. By using the STS curtain method, the external surfaces of pipes are welded with flange slabs, and then the pipes are jacked into soils. However, the nature and extent of the influence of flange slabs on the calculation of jacking force is unclear. This paper presents the first combined theoretical and case study to calculate the increase of jacking forces for circular steel pipes with welded flange slabs during the entire jacking process. The increase of jacking forces was assumed to balance the friction at the soil-pipeline interface. Theoretical formulae were firstly developed to calculate earth pressure based on pressure arch theory and elastic foundation beam theory. A case study was then performed to verify the theoretical results with the field data from Olympic Metro Station on the Shenyang Metro Line 9 in China. Subsequently, factors influencing the calculation of jacking force were analyzed and discussed. Results show that the theoretical formulae produced good results with minor errors. The implications of these findings regarding the prediction of jacking force and selection of hydraulic jack are discussed.

Experimental study on flexural behavior of micro circular steel pipe with grouting

In order to study the bending resistance of grouted micro circular steel tube, pure bending tests on 9 grouted steel tubes were carried out with different grouting materials and three kinds of diameter steel tube. Through the analysis of deflection, surface strain and internal steel bar strain during the test, the deformation characteristics and load-strain relationship of members under load are studied. The ultimate bending capacity and bending stiffness test results are compared with the calculated values of different codes. The results show that the ultimate bearing capacity calculated by different codes is quite different from the test results, and the calculated values of Fujian Provincial Standard DBJ13-51-2010 are in good agreement with the test results and are safe. The bending stiffness at the initial stage calculated by different codes and the bending stiffness at the service stage are also quite different from the test results. The calculation results of AIJ (2002) are in good agreement with the test results and can be used for design calculation after revision.

Design of CFRP-steel hybrid structure pipeline for concrete pumping under ultrahigh pressure

The pipeline is the main channel for concrete pumping in construction, and lightweight, safe, long service life pipeline is very important for concrete pump trucks. This paper presents the design and experimental study on hybrid structure of carbon fiber reinforced polymer (CFRP) filament-winded strengthened circular long steel pipe. The filament-winded CFRP contains three layers: the inner layer for stress sharing of brittle steel tube, the middle layer for connecting to ductile steel flanges and the outer layer for explosion-proof and protection. With calculation of the hybrid structure stress, the design guideline of inner and outer layer CFRP is presented. Based on the design and test of the connection structure between pipe flange and CFRP, this paper conducted an optimization on the filament winding patterns of the middle layer. The experiment result shows the new hybrid structure pipeline can bear the pressure of 17 MPa and the axial loading of 210 kN, and the working requirements of concrete pumping can be satisfied. The test result indicates that the hybrid structure pipeline reduces 43% mass compared with the traditional double-layer steel pipe, and also the service life is 50% increased so as to the explosion-proof safety performance of concrete pump trucks is obviously improved.

The precision calibration of depth and resolution for multibeam sonar in anechoic pool in the laboratory

The multibeam sonar is an important device for underwater survey, of which the measurement precision is a key parameter. We had designed an equipment to calibrate the depth and resolution precision for multibeam sonar in the anechoic pool in the laboratory. The main frame of the equipment is built up by circular and square steel pipes. The absorption materials are laid outside of the pipes, so that the multibeam sonar cannot receive the strong enough reflected acoustic waves from the boundary. We had made a two-dimensional scanning mechanism, which ascends and descends freely for evaluating the depth precision of multibeam sonar. The minimum precision of the depth is 0.1 mm. We had set up a series of iron blocks with the dimension of 0.1,0.2,0.4,0.6,0.8, and 1.0 square meters, respectively, as the standard objects for evaluating the resolution capability of multibeam sonar. In addition, we had placed an underwater camera system to record the iron blocks in time. The result of iron blocks measured by the calibrated multibeam sonar is compared to that recorded by the camera. Because the wavelength of acoustics is larger than that of optics, therefore, good precision of the resolution can be gotten.

Laboratory Experiments for Evaluating Dynamic Response of Small-scaled Circular Steel Pipe

Laboratory Experiments for Evaluating Dynamic Response of Small-scaled Circular Steel Pipe

Denting the oil pipelines by a rigid cylindrical indenter with conical nose by the numerical and experimental analyses

The present research discusses indentation process on the oil pipelines using a rigid indenter in the quasi-static condition by the experimental and numerical analyses. This article investigates influences of internal pressure, diameter and wall thickness of pipes and geometrical characteristics of rigid cylindrical indenters with conical nose such as cone angle, conical nose diameter and cylindrical part diameter on mechanical behavior of the circular steel pipes under concentrated lateral loading (denting). In the experimental part, some specimens made from the steel API5L L245 were prepared and they laterally compressed by a rigid cylindrical indenter with the conical nose to perform the indentation process on them. In the numerical part, some finite element models were prepared and indentation process was simulated on different models with various tube and indenter geometries in different conditions of internal pressure. By comparing the numerical and experimental results, precision and accuracy of the simulations were affirmed. The discussed results show that when tube diameter increases, bending moment arm of the concentrated applied load around the formed plastic hinge lines enhances; therefore, lower lateral load can create a certain plastic deformations in the tube wall; and also, total absorbed energy by the tube enhances. Results demonstrate that when a conical projectile with a certain mass and initial velocity laterally compresses a circular tube, increment of tube diameter causes reduction of probability of the tube failure. The results show that when cone angle of conical indenter decreases and reaches to a certain value that called critical angle, the penetration occurs during the indentation process. Furthermore, it is found that by increasing the diameter of cylindrical part of the indenter, lateral indentation load increases; and when applied internal pressure on the tube increases, ultimate lateral displacement of the indenter decreases; but, the maximum load for the tube wall fracture enhances.

On the ratcheting response of circular steel pipes subject to cyclic inelastic bending: A closed-form analytical solution

The current paper deals with the cyclic plastic response and strain ratcheting of circular steel tubes under repeated inelastic pure bending. A closed-form solution is proposed for the problem. The cyclic softening/hardening behaviour of the material is modelled using a combined bilinear kinematic/nonlinear isotropic hardening rule. The relative hardening modulus in each half-cycle is considered as an extra state variable to account for the non-fading memory characteristics of the material. The cycle by cycle growth (creep) in the ovalisation of the cross-section is modelled using a modified version of the Bailey–Norton creep law. The solution considers the material nonlinearity, the cyclic plasticity effects and the geometrical nonlinearity due to the ovalisation of the cross-section. The model predictions are examined against a number of available test data on the inelastic monotonic and cyclic bending of tubes and reasonable agreements are observed.

뿜칠 피복 원형 철골구조의 비재하 내화성능 평가용 시험체 제안을 위한 연구

단면형상계수는 세계적으로 흔하게 활용되는 공학적 내화구조 성능평가 방법이지만 국내의 경우 단면형상계수의 적용을 위한 제도가 아직 마련되어 있지 못하다. 실제 우리나라의 대부분의 철골조 건축물에서 원형 강관의 사용을 흔히 볼 수 있으나, 인정기관으로부터 성능을 인정받은 뿜칠 피복 철골 보 및 기둥은 대부분이 H형강으로 한정되어 있다. 비재하 시험의 특성상 H형강은 관련규정에 따른 시험규격으로 부재에 대한 평가를 수행하여 크기의 제한 없이 인정범위가 부여되나, 이형 강관의 경우는 형상별로 별도의 내화성능에 대한 인정을 받아야 한다. 본 연구에서는 합리적인 내화구조의 인정범위를 설정할 수 있도록 단면형상계수를 활용하여 뿜칠 피복재의 원형 강관의 적용을 위한 표준 시험체 규격을 제시하고자 한다. The cross-sectional shape factor is used worldwide to evaluate the scientific performance of fire-resistant structures. In South Korea, however, a system for applying a cross-sectional shape factor has not been arranged and circular or rectangular steel pipes are commonly used for large-scale steel frame buildings. On the other hand, coating material-spray steel beams and pillars that have received the certification of a fire-resistant structure from recognized organizations are mostly limited to a H-beam. A H-beam is granted a wide range of certifications without size limitations from a non-loading performance test with test standards based on the relevant provisions. Other types of steel pipe are to be certified for fireresistance according to shape. In this study, a cross-sectional shape factor was used to propose standard testing specifications for the application of coating material-sprayed circular and rectangular steel pipes, eventually to set the scope of certification for reasonable fire-resistant structures.

Tests and Analysis of the Compressive Performance of an Integrated Masonry Structure of a Brick-Stem-Insulating Layer

This paper proposes, for low buildings, an integrated wall structure of a brick-stem-insulating layer, which plays a major part in both heat preservation and force bearing. The research team has tested the thermal performance of the structure, the results of which are satisfying. To further study the force-bearing performance, the paper carries out compressive tests of specimens of different structural design, with two types of bricks, i.e., clay and recycled concrete bricks; three types of stems, i.e., square-shaped wood, square-shaped steel pipe and circular steel pipe; and one type of insulating layer, i.e., fly ash masonry blocks. Afterward, the force bearing performance, damage that occurred, compressive deformation and ductility of all of the specimens are compared. On the sideline, the structure is applied in the construction of a pilot residence project, yielding favorable outcomes. The results indicate that in comparison with a brick wall with an insulating layer sandwiched in between, the integrated wall structure of bricks and fly ash blocks is a more preferable choice in terms of compressive performance and ductility. The integrated wall structure of brick-stem-fly ash blocks delivers much better performance to this end. Note that regarding the stem’s contribution to compressive strength, circular steel pipe is highest, followed by square-shaped steel pipe and then square-shaped wood. The compressive performance of the sandwiched blocks surpasses that of the two brick wall pieces combined by a large margin.

Analytical investigation of pre-stressed, pre-cast beams with steel pipe sleeves

This paper presents an analytical investigation of the structural performance of a pre-stressed, pre-cast concrete beam with steel pipe sleeves. The hybrid pre-cast beam consists of reinforcing steel, a pre-stressing tendon, pre-cast concrete and cast-in-place concrete. Steel sections are installed at both ends of the beam, and steel pipe sleeves are installed at the locations of pipes. The steel pipe sleeves in the pre-cast, pre-stressed beam allow the installation of piping and facility equipment. A strain-compatibility approach was used to predict the influence of the sleeves and pre-stressing on the structural behavior of the hybrid pre-cast beams. It was found that reinforcing rebar, used to reinforce the sleeve openings for circular steel pipes with a diameter of 125 mm, contribute 20% to the flexural load resisting capacity, suggesting that rebar reinforcement can be considered one of the structural components of the beam. The pre-stressed, pre-cast beam with steel pipe sleeve openings exhibited performance similar to that of beams without openings when the reinforcements placed for the sleeve opening were considered part of the flexural stiffness of the beam.

Grouted shear stud connection for steel bridge substructures

This paper discusses the seismic performance of composite connections designed to capacity protect critical welded regions of steel bridge pier connections. Past research has shown that directly welding hollow circular steel pipes to a steel cap beam, regardless of weld configuration, does not mitigate the undesirable failure mode of brittle cracking in the welded region. Hence, capacity protection of the welds becomes an attractive option. A new detail proposed in this paper consists of a composite connection intended to relocate the plastic hinge away from the weld interface. Through full scale quasi-static testing, nonlinear FEA, and scaled shake table testing the connection was shown to perform well.

Nonlinear Analysis on Ultimate Flexural Bearing Capacity of the N-Shaped Steel Tubular Joints

As the author has discovered in the pratice of the project design, the steel pipe size in the truss structure will increase with the expanded span of the spatial structure, far exceeding its original range of application. Therefore, the resulting effect of the joint additional moment on the steel pipe crossing nodes should not be ignored, and how to calculate the ultimate flexural capacity of the steel tubular joints has become an urgent problem to be solved in the joint design. However, the research on ultimate load-carrying capacity is mainly restricted in utilizing the current data and Code for Design of Steel Structures to analyze the axial load-carrying capacity, and the research on ultimate load-carrying capacity of the joint under additional moment is still inadequate. This paper, from the joint stiffness perspective, initiates with brief analysis of the effect of steel pipe size on the joint additional moment so as to illustrate the rationale and necessity for taking into account the joint additional moment in the steel pipe structure, and follows with the adoption of both three-dimensional four-joint 181 elastoplastic shell element and the finite element model (by which N-shaped circular steel pipe crossing nodes is established for the ideal elastoplastic material in ANSYS finite element program) to fit the formula for the flexural capacity of the N-shaped joints based on orthogonal test method and regression technique with geometric nonlinearity and material nonlinearity taken into consideration. It is designed to provide some reference for the design and application of steel tubular intersecting joints in the future.

제작성을 개선한 하이브리드 FRP-콘크리트 합성말뚝의 압축거동

말뚝은 상부구조물에 작용하는 하중을 지반에 전달하는 구조요소로서, 일반적으로 말뚝기초는 지중 또는 수면 아래 지중에 건설된다. 이러한 환경은 부식 또는 염해를 유발하여 말뚝에 손상을 야기한다. 지중 및 수중 구조요소인 말뚝이 손상될 경우, 손상에 따른 내구성을 평가하기 어려우며 추가적인 보수보강 및 유지관리 또한 어렵다. 이 연구에서는 말뚝기초의 내구성과 제작성을 개선하기 위하여 하이브리드 FRP-Concrete 합성말뚝(HCFFT)을 제안하였다. 제안된 HCFFT에 대한 유한요소해석과 실험을 실시하여, 이를 바탕으로 HCFFT의 최대하중 추정식을 제안하였다. 또한, 제안된 HCFFT의 제작과정에서의 문제점을 개선한 새로운 형태의 HCFFT의 형태를 제안하고, 유한요소해석을 실시하여 동일한 직경의 PHC 말뚝과 강관말뚝의 축방향 압축력을 HCFFT 말뚝의 축방향 압축력과 비교하여 HCFFT 말뚝의 장점을 확인하였다. As a fundamental structural element of construction, a pile is constructed to transfer loads from superstructure to foundation. In general, since the pile foundation is constructed in the ground or ground under water, it is difficult to protect from the damages due to moisture and/or salt which create corrosive environment and it is even more difficult to estimate its durability. In this study, in order to enhance the durability and constructibility of the pile foundation, FRP-concrete hybrid composite pile (HCFFT) is suggested. Moreover, equation for the prediction of load carrying capacity of HCFFT circular members under compression is suggested and discussed based on the results of analytical and experimental investigations. In addition, we also conducted the finite element simulation for the structural behavior of new HCFFT composite pile and the result is compared with those of experimental and analytical studies. In addition, the axial loading capacity of new HCFFT composite pile is compared with those of existing PHC pile and hollow circular steel pipe pile, and it was found that the new HCFFT composite pile has advantages over conventional PHC and steel pipe piles.

Transient thermal stress distribution in a circular pipe heated externally with a periodically moving heat source

This study presents the effects of periodically moving heat source on a circular steel pipe heated partly from its outer surface under stagnant ambient conditions. While the pipe is heated with this heat source applied on a certain section having a thickness of heat flux, the water flows through it to transfer heat. It is assumed that the flow is a fully-developed laminar flow. The heat source moves along from one end of the outer to the other end with a constant speed and then returns to the first end with the same speed. It is assumed that the heat transfer rate has a constant value, and that the thermo-physical properties of the steel do not change with temperature (elastic analysis). The numerical calculations have been performed individually for a wide range of thermal conductivity of steel and for different thicknesses of heat flux. The moving heat source produces the non-uniform temperature gradient and the non-uniform effective thermal stress, and when it arrives at the ends of the pipe, the temperature and effective thermal stress ratio profiles rise more excessively. The tangential component is more dominant in the effective thermal stress than the radial component.

A Constitutive Model for Circular Steel Pipe by Spatial Hysteretic Test

As a rapid developing structure form in late thirty years, space structures are widely used in all kinds of large-scale public building. However, this structure form usually appears an obvious deformation and serious material plastic under severe earthquakes event. Under this circumstance, the material will be experienced cyclic and accumulated damage which have an important effect on the structural behavior and should be considered in the constitutive model. Tests of thirty circular steel tubes were thus conducted under constant axial and cyclic horizontal loads to derive the rational constitutive model with consideration of material damage accumulation. Further, finite-element model were developed using ABAQUS to simulate tube behavior under load. And then the material damage accumulation was dealt with by a user-defined subroutine encoded with ABAQUS. The parameters in the constitutive model are evaluated by experimental results using the least square method fitting between experimental curve and numerical curve. The comparison between the theory and the experiment with the interface program shows that theoretical curves are in good agreement with experimental curves, which proves not only the constitutive equation is accurate but also the finite element program is applicable for theoretical analysis.

Test Research on Spatial Hysteretic Behavior of Circular Steel Pipe

A test to study the spatial hysteretic behavior of circular steel pipe subjected to cyclic load was designed. The test setup and data acquisition system were applicable for three-dimension load. A total of 30 specimens were selected by cross section and height of the circular steel pipe to cover different slenderness ratios, different load modes. The specimens were divided into five groups by different load modes. The hysteretic curves changing with different slenderness ratios and different load modes were got after completing the experiment. These lay the foundation of the subsequent research on constitutive model about steel.

Propane–air pipe explosion experiments. Data for estimation of 1-D burning velocity in slow regimes

Flame propagation in circular steel pipes with inner diameter of 22 mm and lengths of 1, 2 and 5 m has been studied experimentally. The combustible gas mixtures used were propane–air mixtures at various equivalence ratios, which sustain flame propagation in a slow regime in this pipe geometry. The results obtained are in agreement with comparable reported experiments. Initial flame propagation is governed by the laminar flame velocity, but the flame propagation in a slow regime will depend strongly on the acoustic oscillations in the pipe from the time when the first rarefaction wave, which was reflected at the pipe outlet, reaches the flame front. The main purpose of performing the experiments was to obtain a set of data for the numerical simulations. A quasi 1-D burning velocity is determined numerically with a Matlab version of the random choice method (RCMLAB) on the basis of the experimental pressure records. This estimated burning velocity is used as input to the combustion model in the RCMLAB code. It seems to be good agreement between the numerical results and experiments, except for some variance probably caused by the pipe outlet. The expansion at the pipe outlet is important for the acoustic oscillations and our results show the importance of the modelling of the outlet.