Pipe Sleeve Research Articles

Estimation of Failure Mode of Mortar-Filled Sleeve Rebar Splices

In order to establish a more rational structural design method for mortar-filled sleeve rebar splices, it is necessary to analyze and evaluate structural factors affecting the structural performance of these rebar splices. It is very desirable to be able to quantitatively estimate the failure mode of the splices at the design stage. A method for estimating the failure mode of mortar-filled sleeve rebar splices presented from the existing research is not clear because the boundary of failure mode is not expressed in formulas. There are also limitations using the methods because the research is based on limited number of test variables, insufficient number of test specimens, and the fact that only steel pipe sleeves were used. Therefore, to establish a more general and comprehensive failure mode estimation method, it needs to be presented in a more quantitative and explicit fashion and evaluated using more diverse variables. In this study, as part of an effort to generate basic data for the establishment of a more rational and quantitative structural design method for mortar-filled sleeve rebar splices, the failure mode estimation method is presented based on the existing bond strength equations of sleeve rebar splices. In addition, to examine the suitability of this failure mode estimation method, the failure modes of 303 sleeve rebar splices were evaluated. The evaluation results indicated that the failure mode estimation method for mortar-filled sleeve rebar splices proposed by this study would yield a failure mode estimation with a sufficiently practical accuracy.

Design and application of an extension tube for ventilator pipeline

At present, the extension tube of the ventilator, a long corrugated tube used in clinical practice, needs to be disconnected from the endotracheal tube when performing open sputum suction. Under positive pressure, the condensed water containing pathogenic microorganisms in the ventilator will be splashed. Some will form aerosol suspended in the air, pollute the air, increase the risk of cross-infection and operator pollution, while the ventilator will emit a corresponding alarm sound, resulting in noise pollution. Based on the above factors, a ventilator pipeline extension tube was designed by the medical staff of department of critical care medicine of the Eighth Medical Center of People's Liberation Army General Hospital and department of critical care medicine of Beijing Friendship Hospital of Capital Medical University, and was obtained the National Utility Model Patent of China (ZL 2020 2 1476518.X). The device consists of the main pipe, first pipe sleeve, second pipe sleeve, valve body, joystick, axial sleeve, etc., which can not only effectively avoid air pollution and reduce the risk of cross-infection, but also reduce noise pollution and the negative impact of loud noise on patients and medical staff.

UHPC grout-filled pipe sleeve with bolts for large-diameter deformed bars: Analytical model on the tensile resistance and design method

A novel UHPC grout-filled pipe sleeve with bolts was put forward for connecting large-diameter deformed bars and its feasibility was experimentally verified in a previous study. But it is not easy to rapidly broaden its application partly due to the lack of relevant calculation and design knowledge. This study aims to establish an analytical model on the tensile resistance that is dependent on the deformed bar-UHPC grout and UHPC grout-steel pipe interfaces, and develop a design method for the proposed pipe sleeve. In the model, the former interface resistance was analytically calculated considering the friction resistance, bearing of ribs against UHPC grout, and steel pipe's confinement. A dimensionless index ηb-g was defined to measure the relationship of the bond stress and pressure at the interface, and calibrated based on the experimental results. The latter interface resistance was analytically calculated considering the interface bond strength and resistance of bolts. Experimental results were adopted to verify the analytical model. A design method was developed for the pipe sleeve based on the verified analytical model, and a design case was given to illustrate how to use it. Results show that the analytical model can accurately predict the two interface resistances. ηb-g is respectively recommended for three categories of pipe sleeves, that are distinguished by the existence of bolts and grout type. The design method is convenient to provide a feasible design scheme of the pipe sleeve for a specified large-diameter deformed bar, of which the embedded length can be reduced to be 6 ~ 7 times bar diameter.

Modeling of mechanical behavior of corroded X80 steel pipeline reinforced with type-B repair sleeve

This work investigated stress response of a corroded X80 steel pipeline repaired by a type-B sleeve to internal pressure by finite element modeling. Firstly, a three-dimensional numerical model of corroded pipeline reinforced with type-B sleeve was developed, and its accuracy and reliability were verified by the burst test results and the theoretical analytical solution, respectively. Second, the von Mises stress of the pipe body, sleeve and fillet weld was simulated under various affecting factors, i.e., internal pressure, corrosion defect dimension (depth, length and width) and sleeve length. Finally, a parameter sensitivity study was conducted to determine the effects of corrosion geometry and sleeve length on the repair efficiency. The main investigation results show that the type-B sleeve repair method is effective to restore the pressure-bearing capacity of the pipeline at the corrosion defect, and the burst failure of repaired pipeline always occurs at the region far away from the defect and sleeve. At the limit state of burst, the local defective region shows the highest stress, followed by the fillet weld, and the repair sleeve has the smallest stress, thus the maximum equivalent stress of the corroded zone is suggested to be used for measuring the repair efficiency of the repaired pipe by type-B sleeve. The sleeve-repair effectiveness is affected by depth of the corrosion defect, a deep corrosion defect reduces the performance of the sleeve repair compared with a shallow defect. The effect of the corrosion defect length on sleeve repair depends on the defect depth. Furthermore, there exist a critical length of the defect that affect the repair efficiency. The corrosion defect width shows limited effect on stress level at the defect of the repaired pipe. At last, a new method based on stress analysis is proposed to optimize the sleeve length for repairing a corroded pipeline.

Experimental study on a novel UHPC grout-filled pipe sleeve with mechanical interlocking for large-diameter deformed bars

Grouted sleeve splice is a competitive alternative to reinforcement connections of accelerated bridge construction (ABC). When it is used to connect large-diameter deformed bars, overlong development length is required, although the decreased amount of connected bars and increased construction tolerance can accelerate construction speed. This paper aims to develop a novel ultra-high performance concrete (UHPC) grout-filled pipe sleeve with bolts for large-diameter deformed bars. It is expected to shorten the embedded length and delay grout crushing and splitting caused by bolts using UHPC's high material properties. A direct tensile test was conducted on 21 specimens to validate the feasibility, investigate the design parameters' effects, and explore the working mechanism of the pipe sleeve. Results show that the proposed pipe sleeve is feasible to connect large-diameter deformed bars with an embedded length of 5db. There are four failure modes including grout bond failure without/with bolts as well as bar bond failure without/with bolts in this test. UHPC without steel fiber is a preferred grout for the pipe sleeve because steel fiber can weaken grout fluidity and reduce bar-grout bond strength as well as grout-pipe bond strength. The existence of bolts can significantly enhance bar-grout bond strength as well as grout-pipe bond strength. The grout-pipe bond performance is sensitive to the depth of bolts in grout, amount of bolts, and distance of bolts to the end. When the pipe sleeve is used for deformed bars with higher strength, bearing capacity is slightly increased and deformation capacity is markedly weakened for bar-grout bond behavior. A greater cross dimension of the steel pipe is a good choice to avoid grout bond failure.

Alternative design of pipe sleeve for liquid removal mechanism in mortar slab layer

Porosity is one of the mortar’s characteristics that can cause problems, especially in the room space that used high amount of water, such as bathrooms. Waterproofing is one of the technology that normally used to minimize this problem which is preventing deep penetration of liquid water or moisture into underlying concrete layers. However, without the proper mechanism to remove liquid water and moisture from mortar system, waterproofing layer tends to be damaged after a long period of time by the static formation of liquid water and moisture at mortar layer. Thus, a solution has been proposed to drain out water that penetrated into the mortar layer. This paper introduces a new solution using a Modified Pipe Sleeve (MPS) that installed at the mortar layer. The MPS has been designed considering the percentage surface area of the pipe sleeve that having contact with mortar layer (2%, 4%, 6%, 8% and 10%) with angle of holes of 60°. Infiltration test and flow rate test have been conducted to identify the effectiveness of the MPS in order to drain out liquid water or moisture from the mortar layer. In this study shows that, MPS surface area 10%, angled 60°, function effectively as a water removal compared to other design.

Design of Multi Hole Machining Equipment for Flange Parts Based on CAD/CAM

According to the situation of multi hole machining with linear circular flange flange parts, a device is analyzed and designed, which can process multiple flange holes at the same time, and the design of the device including fixture design and multi spindle box design. the three - dimensional modeling and analysis software is used, make a study on the design and manufacture of the flange hole of the 96 pipe sleeve, through the selection of hardware, such as drill bits, machine tools, gears, shafts, and the simulation of Ansysworkbench force of main parts, obtain the design device and the processing method suitable for mass production of linear round flange parts with seat. It also can achieve drilling, reaming and tapping function conversion by adjusting the speed and dril.

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.

Bond Strength of Mortar-filled Steel Pipe Splices Reflecting Confining Effect

This study purposed to evaluate the adequacy of existing equations proposed for calculating the bond strength of reinforcing bar splices in a mortar-filled steel pipe sleeve, and to propose a method for estimating the bond strength of bar splices that quantitatively reflects the confining effect of a steel pipe sleeve. For this purpose, we analyzed a total of 40 experimental mortar-filled steel pipe splices in which bond failure occurred, and examined how the confinement effect of steel pipe affects the bond performance of these splices.The study results showed that existing methods of estimating the bond strength of the bar splices did not adequately estimate the bond strength of reinforcement splices in a mortar-filled steel pipe sleeve. In addition, based on the results of the tests on the 40 analyzed specimens, we performed multiple regression analysis with independent variables such as sleeve shape and the development length of a bar, and proposed the confining pressure of mortar-filled steel pipe splices. By applying the proposed confining pressure to Untrauer and Henry's bond strength equation reflecting the lateral confining pressure, we computed the bond strength of mortar-filled steel pipe splices more accurately than existing bond strength estimation methods.

파괴모드 추정방법을 이용한 모르타르 충전식 슬리브 철근이음의 강성 평가

본 연구에서는 기존의 모르타르 충전식 슬리브 철근이음에 대한 부착강도식으로부터 유도한 이 철근이음의 파괴모드 추정방법을 이용하여, AIJ 규준에 의하여 평가한 이 슬리브 철근이음의 강성을 검토하였다. 이것을 위하여 261개 모르타르 충전식 슬리브 철근이음의 기존 실험자료를 채택하여 실험의 결과를 분석한 결과에 의하면 모르타르 충전식 철근이음의 파괴모드 추정방법은 돌기가 없는 강관 슬리브에 SD500 철근을 사용한 철근이음을 제외한 모르타르 충전식 슬리브 철근이음에 대한 강성을 효과적으로 평가할 수 있었다. 그리고 이 슬리브 철근이음의 파괴모드 추정방법에 적용하여 철근의 인장파단 영역에 있는 실험체 중에 주물 슬리브와 돌기가 있는 강관 슬리브를 사용한 실험체에서 SD400 철근을 사용한 경우는 98%, SD500 철근을 사용한 경우는 모든 실험체가 단조가력 시의 강성이 AIJ 규준의 A급 이상인 것으로 나타났고, 철근의 인장파단 영역에 있는 모든 실험체는 슬리브의 종류와 슬리브에 매입한 철근 종류에 관계없이 반복가력 시의 강성이 AIJ 규준의 A급 이상인 것으로 나타났다. The objective of this study is to evaluate the stiffness of mortar-filled sleeve bar splice using estimation method of failure mode in the sleeve reinforcement splice. To attain this goal, we analyzed the test results of 261 actual-sized mortar-filled sleeve splice specimens. The study results showed that the estimation method of the failure mode in mortar-filled sleeve bar splice made an effective estimate of the stiffness in this bar splice with the exception of specimens with SD500 bars and smooth pipe sleeve. Especially, of the specimens with cast sleeve or uneven pipe sleeve in the range of reinforcement fracture using the estimation method of the failure mode in mortar-filled sleeve splice, specimens over 98% with SD400 bars and all specimens with SD500 bars had the stiffness capacity of higher than "A" class of AIJ code in monotonic loading. In addition, of the specimens in the range of reinforcement fracture using the estimation method of the failure mode in mortar-filled sleeve splice, all specimens with SD400 bars and SD500 bars had the stiffness capacity of higher than "A" class of AIJ code in cyclic loading.

Material Factors Analysis of the Cracking in 0Cr12Mn5Ni4Mo3Al Stainless Steel Pipe Sleeve on Aircraft Flare-Less Pipe Joints

It is shown that the discreteness of the chemical compositions of 0Cr12Mn5Ni4Mo3Al steel is large and the range of the Cr/Ni equivalent ratio is wide, which has big impact on the content and morphology of ferrite and easy to occur cracking phenomenon when bearing, based on the chemical compositions analysis of pipe sleeve on aircraft flare-less pipe joints. It can be found that the chemical compositions of cracked pipe sleeve are almost meeting the requirements, but the Cr/Ni equivalent ratio is on the high side. So it can be concluded that the fracture failure of pipe sleeve is closely related to the content, shape and distribution of δ-ferrite. Thus, the available solution of the cracking in 0Cr12Mn5Ni4Mo3Al stainless steel pipe sleeve is to reduce the Cr/Ni equivalent ratio within the permissive of nominal chemical compositions and adjust the hot working process to form the reasonable morphology and distribution of δ-ferrite.

Fracture Analysis of Pipe Sleeve on Extrusion Flare-Less Pipe Joints for Aircraft Hydraulic Pipe

The forming process of aircraft hydraulic pipe joints is investigated through experiments and analyses to solve the cracking problem of pipe sleeve on extrusion flare-less pipe joints. It can be concluded that the internal cause of the fracture failure is connected with the content, shape and distribution of δ-ferrite in 0Cr12Mn5Ni4Mo3Al high strength stainless steel, and the external cause is associated with the bearing behavior in the extrusion-bulging process of pipe sleeve. The crack is formed in the criss-crossing section of δ-ferrite on the function of shear stress in the stress concentration position, which belongs to ductile deformed crack. It eventually induces the intergranular fracture of pipe sleeve along the long axis with the expanding of subsequent crack.

On the acoustical properties of cylindrical shells and pipe sleeves

Acoustical properties of cylindrical shells and pipes differ greatly from plane sound insulation properties. Sometimes opposite results are achieved, especially at low frequencies. The report presents these differences and causes that have been proved theoretically. The sound permeability through sleeves has not been fully investigated as yet. Here analysis and comments of the works performed are presented.

Bolted glass-fibre-reinforced plastic joints

Test results are presented for single fastener glass-fibre-reinforced plastic (GFRP) members connected with GFRP threaded rods, steel threaded rods, and steel bolts. Twenty-eight joints were tested in tension and thirty-five were tested in compression. For some of the tests, a GFRP pipe was used as a protective sleeve for the threads of the steel and GFRP threaded rods. The effect of fastener strength and stiffness on the load carrying capacity of the joints is reported. The major findings for both the tension and compression tests were that joints constructed with a GFRP threaded rod had approximately half the strength of joints constructed with a steel threaded rod. Also, joints constructed with a GFRP threaded rod and GFRP pipe sleeve were at least a third stronger than joints constructed with a GFRP threaded rod alone. The GFRP members used consisted of a pultruded glass fibre sheet, which was composed of symmetrically stacked, alternating layers of identically orientated unidirectional E-glass fibres and randomly orientated E-glass continuous strand mat. The maximum load carrying capacity decreased with increasing angle of loading with respect to the unidirectional fibres, but this was more pronounced for the tension tests than for the compression tests. For the tests performed, it was sufficient to finger tighten end nuts; indeed, tightening end nuts by a half turn-of-the-nut slightly decreased the strength of the joints. Key words: glass-fibre-reinforced plastic, connections, fibreglass bolts, experimental.

Slipforming of Reinforced Concrete Shield Building

The unique design and construction features of slipforming the heavily reinforced concrete cylindrical shield walls at the Satsop nuclear plant site are presented. It proved that, with proper planning, design, and coordination, the slipform construction technique can be successfully applied to large and heavily reinforced concrete structures. The shield walls were designed in compliance with seismic requirements which resulted in the need for reinforcing steel averaging 550 pounds per cubic yard (326 kg/m3). A 25 ft (7.6 m) high, three-deck moving platform was designed to permit easy installation of the reinforcing steel, embedments, and blockouts, and to facilitate concrete placement and finishing. Two circular box trusses, one on each side of the shield wall, were used in combination with a spider truss to meet both the tolerance and strength requirements for the slipform assembly. Use of preassembled, lifted-in-place sleeve tower racks that combined diagonal and vertical bars for the openings with two vertically aligned pipe sleeves greatly eased the installation. Specific recommendations for future slipforming are also presented.

Scale Models for Complex Reinforcement

The use of scale engineering models has provided an effective tool in the development of complex, heavily reinforced concrete structures for the Seabrook Nuclear Power Station. Two large general areas and a number of specific congested areas were scale modeled to facilitate: planning design, placing detail checking and installation of the complex concrete reinforcing and associated anchor bolt, pipe sleeve, conduit and all other embedded plates and anchorages. The early use of these models has resulted in substantially eliminating construction problems by relating interference conditions to the designer at a stage where timely, efficient modifications could be made. These models have also served construction efforts as effective planning and instruction tools.

Plain End Pipe and Specials Versus Bell and Spigot Pipe and Solid Sleeves

Plain End Pipe and Specials Versus Bell and Spigot Pipe and Solid Sleeves