Perforated Section Research Articles

Research and application of migration and plugging mechanism of temporary plugging balls in multicluster fracturing of horizontal wells

Plugging and diverting stimulation technology using temporary plugging balls (PDSTB) in horizontal wells is one of the effective measures to enhance production in heterogeneous carbonate reservoirs. However, the migration and plugging mechanism of temporary plugging balls in horizontal wells remain unclear, leading to suboptimal field application. Based on the Lagrangian method, the migration and plugging models of temporary plugging balls were established. The study investigated the migration and plugging mechanism of temporary plugging balls. It analyzed the effects of parameters such as displacement on the plugging efficiency. The results show that the flow field in the perforation section is significantly affected by the displacement. Temporary plugging balls show three states of plugging: one ball plugging one shot-hole, multiple balls plugging one shot-hole, and balls remaining in the wellbore. The plugging efficiency initially increases, and then, decreases with the increase in displacement and the ball diameter. The plugging efficiency initially increases, and then, stabilizes with the increase in the viscosity of the carrying fluid and the usage ratio of balls. Plugging efficiency decreases with increasing density of balls. The greater the pressure difference at the outlet of the perforation section, the higher the plugging efficiency in the advantageous inlet section. Based on these results, the field construction of Well M was guided. The gas production was 142.66 × 104 m3/d after stimulation, and the production increase was significant. This study provides a theoretical basis for optimizing and designing the parameters of PDSTB in carbonate long horizontal wells.

Research and Application of Intelligent Well Completion Technology in Offshore Oilfield

Abstract The reservoirs in Bohai oilfield were mainly composed of unconsolidated sandstone. A single multi-layer gravel packing operation could greatly reduce the packing operation time and improve the operation efficiency. However, the conventional tools were limited by the double-layer central tube structure, which resulted in large packing friction and high pressure consumption due to its small annular area, which limited the limit operation length and displacement. In order to solve this problem, we independently developed a double-layer screen tube one-time multi-layer fracturing packing tool, innovatively set up production interlayer in the screen pipe, formed a bypass diversion screen pipe system, so as to reduce the downward entry of one layer of central pipe during filling, simplify the structure of the filling string, and greatly reduce the friction of the string. The results showed that the limit packing length and displacement were 1200m and 45bpm respectively, which were 300% and 50% higher than the traditional packing tools, and the operation range of the tools was improved. The safety and efficiency of double screen fracturing and filling operation were ensured by innovating the quick connection method of double screen pipe, fast pressure test tool and expanding switch tool of oil pipe. The application in well LX has realized the purpose of sand control by five layers filling in one time. The packing length was more than 400 m. Combined with the problems in field operation, it had been applied in 5 areas The improvement suggestions of the tool are put forward. The double screen pipe one-time multi-layer fracturing packing tool and its supporting technology realized the ideal packing parameter requirements of low pump pressure and high return velocity. It could be widely used in sand control operation of multi-layer gravel packing fracturing in large-span perforation section in the future, which greatly improved the operation efficiency and has good economic benefits and promotion value.

A comparison of micromorphic gradient‐extensions for anisotropic damage

AbstractThe modeling of inelastic phenomena with tensor‐valued internal variables requires a regularization to counteract mesh dependence. Here, we consider the regularization of anisotropic damage at finite strains and seek for an efficient formulation based on a reduced number of nonlocal degrees of freedom. We, thus, equip the brittle version of an anisotropic model with different gradient‐extensions in the micromorphic framework using a full and a reduced regularization of the damage tensor. The models are compared in the structural simulation of an asymmetrically notched specimen with a perforated shear band section. High agreement is observed between the full and the reduced regularization with two nonlocal degrees of freedom. Furthermore, we present a novel study of the evolution of the reduced micromorphic field variables.

Research on the Law of Crack Propagation in Oil Well Fracturing Process

In the field of oilfield fracturing development, a profound understanding of the evolution and propagation of damage during the fracturing process is crucial for preventing well water coning and channeling. This study aimed to unravel the complexity of damage evolution during fracturing and elucidate the causes of well water flooding phenomena. To accurately describe the damage propagation laws, a damage constitutive model considering compaction and post-peak correction parameters was established in this research. The model, through parameter adjustment, enhances the precision of stress calculation during the rock compaction phase and accounts for the stress degradation pattern subsequent to damage. This model was applied to simulate the damage evolution under various conditions in oil layer profiles and wellbore cross-sections, including the impact of different perforation angles, natural fracture patterns, and the ratio of longitudinal to transverse boundary pressures. The research concludes that well water channeling and flooding are primarily caused by damage propagation and the connectivity with adjacent water-bearing formations. The proposed rock damage constitutive model demonstrated an accuracy improvement of more than 3% compared to previous studies. Additionally, the study discovered that when the angle between the perforation section and the formation exceeds 30°, the risk of fracture propagation into adjacent layers increases, leading to an elevated risk of post-fracturing water flooding. The presence of natural fractures in the oil layer provides a conduit for damage propagation, accelerating the process of damage in the oil layer. Furthermore, the perforation angle and the ratio of boundary pressure loads during the fracturing process were identified as the main factors influencing the direction change of fracture propagation. The conclusions drawn from this study provide a scientific basis for preventing post-fracturing water channeling and flooding issues and offer new perspectives for the development of well fracturing technology, aiding in the resolution of water flooding problems associated with well fracturing.

Transportation and sealing pattern of the temporary plugging ball at the spiral perforation in the horizontal well section

Multistage fracturing of horizontal wells is a critical technology for unconventional oil and gas reservoir stimulation. Ball-throwing temporary plugging fracturing is a new method for realizing uniform fracturing along horizontal wells and plays an important role in increasing oil and gas production. However, the transportation and sealing law of temporary plugging balls (TPBs) in the perforation section of horizontal wells is still unclear. Using COMSOL computational fluid dynamics and a particle tracking module, we simulate the transportation process of TPBs in a horizontal wellbore and analyse the effects of the ball density, ball diameter, ball number, fracturing fluid injection rate, and viscosity on the plugging efficiency of TPB transportation. This study reveals that when the density of TPBs is close to that of the fracturing fluid and a moderate diameter of the TPB is used, the plugging efficiency can be substantially enhanced. The plugging efficiency is greater when the TPB number is close to twice the number of perforations and is lower when the number of TPBs is three times the number of perforations. Adjusting the fracturing fluid injection rate from low to high can control the position of the TPBs, improving plugging efficiency. As the viscosity of the fracturing fluid increases, the plugging efficiency of the perforations decreases near the borehole heel and increases near the borehole toe. In contrast, the plugging efficiency of the central perforation is almost unaffected by the fracturing fluid viscosity. This study can serve as a valuable reference for establishing the parameters for temporary plugging and fracturing.

Parametric study on the assessment of the local buckling behavior of perforated square hollow sections with non-uniform wall thickness under axial compression

The aim of this rigorous parametric study is to explore the influence of perforations on the local buckling behavior of square hollow sections (SHSs) possessing non-uniform wall thickness. A finite element procedure followed in the current study has been first validated against existing test results documented for the local buckling behavior of the perforated SHS with uniform web and flange segment thickness under axial compression. The linear elastic eigenvalue buckling and elastoplastic buckling analyses have been implemented using the Abaqus engineering finite element code. The verification of the numerical procedure has been achieved by favorably comparing the finite element results with the existing test results in terms of the first local buckling mode shape and load-end shortening curves of the perforated SHS with uniform wall thickness. . The verified numerical procedure has been applied to the problem of finding the perforation effect on the local buckling response of the SHS with non-uniform thickness. Finite element analyses have been performed for four various web width-to-perforation diameter ratios ranging from 0.3 to 0.9. Finite element analysis results have revealed that the presence of perforations does not influence the local buckling mode shape of the SHS but considerably affects the critical local buckling loads. The results have put forth that increasing perforation diameter leads to a more pronounced and drastic decrease in the critical local buckling load. The outcomes of the study have also shown that the critical post-buckling load of the SHS with non-uniform wall thickness is less susceptible to perforations compared to the SHS with uniform wall thickness. The results obtained in the context of this parametric study have been made available to practical engineering for use in actual design of the perforated SHSs.

Assessment of the tolerance angle for pedicle screw insertion.

Cannulation process intervenes before implantation of pedicle screw and depends on the surgeon's experience. A reliable experimental protocol has been developed for the characterization of the slipping behavior of the surgical tool on the cortical shell simulated by synthetic materials. Three types of synthetic foam samples with three different densities were tested using an MTS Acumen 3 A/T electrodynamic device with a tri-axis 3 kN Kistler load cell mounted on a surgical tool, moving at a constant rotational speed of 10° mm-1 and performing a three-step cannulation test. Cannulation angle varied between 10° and 30°. Synthetic samples were scanned after each tests, and cannulation coefficient associated to each perforation section was computed. Reproducibility tests resulted in an ICC for Sawbone samples of 0.979 (p < 0.001) and of 0.909 (p < 0.001) for Creaplast and Sawbone samples. Cannulation coefficient and maximum force in Z-axis are found the best descriptors of the perforation. Angular threshold for perforation prediction was found to be 17.5° with an area under the curve of the Receiver Operating Characteristic of 89.5%. This protocol characterizes the cannulation process before pedicle screw insertion and identifies the perforation tool angle until which the surgical tool slips on the cortical shell depending on bone quality.

A New Experimental Method for Acid Pretreatment in Perforated Horizontal Wells: A Case Study of Mahu Conglomerate Reservoir

The Mahu Oilfield in Xinjiang, China, is the world’s largest conglomerate oilfield, with a daily output of more than 8000 tons. In the fracturing of perforated horizontal wells, the breakdown pressure is high, resulting in difficulties in their treatment. Acid pretreatment has been applied to reduce the breakdown pressure in the field, but with poor performance. Few studies have been conducted on how acid pretreatment affects the breakdown pressure under perforation conditions in the Mahu conglomerate reservoir. Also, existing fracturing or acid pretreatment experiments cannot simulate perforation well. Therefore, a new method was developed to make perforations by hydro jetting the fracturing specimens (300 mm × 300 mm × 300 mm) first. It can achieve specified perforation parameters, including the perforation angle, position, and length. Subsequently, true triaxial hydraulic fracturing experiments were conducted on the conglomerate specimens obtained from the Mahu area. The effects of the acid pretreatment on the fracture initiation and breakdown pressure were investigated by injecting the perforation section of the conglomerate using various acid systems. The study results showed that the perforation made by the new apparatus was extremely close to the perforation on-site. The acid pretreatment effectively dissolved minerals and could decrease the breakdown pressure down to 7.7 MPa. A combination of 6%HF + 10%HCl was recommended for the acid pretreatment in the Mahu conglomerate reservoir. A total of 60 min acid–rock contact time is necessary for sufficient rock dissolution. The mechanism of the acid pretreatment to decrease the breakdown pressure is that the rock dissolution by the acid reduces the rock tensile strength and increases the permeability. The raised permeability increases the fluid pressure of the reservoir near the wellbore so as to reduce the breakdown pressure of the formation. The research results provide technical support for reducing construction difficulty and optimizing parameters in the Mahu Oilfield.

A Hybrid Data-Physics Framework for Reservoir Performance Prediction with Application to H2S Production

Summary Model-based reservoir management workflows rely on the ability to generate predictions for large numbers of model and decision scenarios. When suitable simulators or models are not available or cannot be evaluated in a sufficiently short time frame, surrogate modeling techniques can be used instead. In the first part of this paper, we describe extensions of a recently developed open-source framework for creating and training flow network surrogate models, called FlowNet. In particular, we discuss functionality to reproduce historical well rates for wells with arbitrary trajectories, multiple perforated sections, and changing well type or injection phase, as one may encounter in large and complex fields with a long history. Furthermore, we discuss strategies for the placement of additional network nodes in the presence of flow barriers. Despite their flexibility and speed, the applicability of flow network models is limited to phenomena that can be simulated with available numerical simulators. Prediction of poorly understood physics, such as reservoir souring, may require a more data-driven approach. We discuss an extension of the FlowNet framework with a machine learning (ML) proxy for the purpose of generating predictions of H2S production rates. The combined data-physics proxy is trained on historical liquid volume rates, seawater fractions, and H2S production data from a real North Sea oil and gas field, and is then used to generate predictions of H2S production. Several experiments are presented in which the data source, data type, and length of the history are varied. Results indicate that, given a sufficient number of training data, FlowNet is able to produce reliable predictions of conventional oilfield quantities. An experiment performed with the ML proxy suggests that, at least for some production wells, useful predictions of H2S production can be obtained much faster and at much lower computational cost and complexity than would be possible with high-fidelity models. Finally, we discuss some of the current limitations of the approach and options to address them.

Research on the erosion law of shale gas casing perforation hole during fracturing

During the fracturing process of shale gas wells, the high-speed injection of sand-carrying fluid throttles at the perforation casing hole, resulting in erosion at the hole, increasing the geometric parameters of the orifice and even producing cracks, affecting the fracturing construction effect and safety. Therefore, the flow field, the movement trajectory of particles and the erosion law of the perforated holes under different displacement and pump pressure were analyzed by using numerical simulation software and Euler-Lagrangian particle tracking theory, and the simulation analysis results were verified by the full-size physical erosion test of the perforated orifice of the casing. The analysis results show that with the increase of displacement, the erosion rate of the eyelet continues to increase, and the erosion rate of the eyelet in the direction of the liquid inlet is significantly greater than that of the bottom of the casing, and the degree gradually decreases in all directions. Increasing the fracturing construction displacement not only increases the erosion rate and diffusion area at the borehole, but also increases the erosion rate of the pipe wall near the borehole, which will accelerate the thinning of the wall thickness of the casing and affect the service safety of the perforated section casing.

The productivity segmented calculation model of perforated horizontal wells considering whether to penetrate the contaminated zone

Perforation technology is often used to improve the productivity of horizontal wells in oilfield exploitation. During the perforation process, the formation seepage mode and productivity will change accordingly whether the contaminated zone is shot through. If we continue to use the previous productivity formula, it will cause a large calculation error and bring economic loss to the development of oil and gas fields. Firstly, based on the principle of equivalent seepage resistance, the reservoir-hole inflow profile in these two cases is analyzed in detail, and the reservoir-hole seepage model is constructed in different regions. The perforated horizontal well section is divided into N micro-unit sections, and the pressure drop model in the wellbore is constructed using the fluid mechanics theory. A new perforated horizontal well productivity prediction model is then created by coupling the reservoir-hole seepage model with the pressure drop model in the wellbore as a whole to accurately reflect the production performance of the perforated horizontal well. Through comparison and verification, it is concluded that the calculation results of the model are more precise, which can greatly reduce the productivity error. This method is reasonable and practical. When the oilfield’s actual well data is substituted into this model, it is discussed and analyzed that the reservoir’s physical characteristics, contamination level, and perforation completion parameters all have an impact on the productivity of horizontal wells, with the original formation’s permeability and reservoir contamination thickness having the most pronounced effects. These findings may effectively direct the design of technological processes and performance impact prediction.

Research on the failure analysis and prediction method of casing deformation under the synergistic effect of sand production and corrosion

Casing deformation is one of the common problems encountered when developing weakly consolidated sandstone reservoirs. This study analyzes the types, causes, and influencing factors of casing deformation based on oil field production data, downhole operation records, and multi-arm caliper logging results. Based on the natural balance arch theory, the geometric and mathematical models of the sand production cavity were constructed, and the theoretical formulas of casing force, casing critical force, and cavity volume were derived. The casing deformation mechanism under the synergistic effect of multiple factors was explored, and a theoretical prediction method for casing deformation was established. The results indicate that casing deformation is primarily attributed to two factors: the transfer of overlying rock pressure to the casing due to sand production in the reservoir and casing corrosion. The casing force is positively correlated with the span of the cavity and negatively correlated with the height of the cavity. Under the same conditions, the shorter the perforation section, the easier it is for the casing to deform. Due to the characteristics of sand production in the reservoir, a stable cavity will be formed in the early stages of development. At this time, the casing force is not enough to cause deformation. However, as time goes by, corrosion gradually reduces the critical force for casing deformation. When the wall thickness is reduced to a certain extent, the casing will deform. Casings with medium and small flexibility will undergo plastic buckling or strength failure. Increasing the steel grade and wall thickness of the casing can increase the critical deformation force of the casing. Highly flexible casings will undergo elastic buckling, and only increasing the wall thickness of the casing can increase the critical force of casing deformation. Correspondingly, reducing the corrosion rate of casing can indirectly increase the critical force of casing deformation. Finally, thirty sand production wells were randomly selected to evaluate the casing deformation prediction method. The overall prediction accuracy reached 86.6%, and the prediction accuracy for casing deformation wells reached 95%. This study provides strong theoretical support for casing deformation prediction and further optimization of casing design.

Sliding on cortical shell: Biomechanical characterization of the vertebral cannulation for pedicle screw insertion

BackgroundPedicular screws pull-out has been well studied unlike their insertion. A need for characterizing cannulation before pedicle screw implantation is highlighted in literature and offers promising prospects for future intra-operation instrumentation. A reliable cannulation protocol for ex-vivo testing in swine and cadaver vertebrae is presented in this work to predict extra pedicular perforation. MethodsAn MTS Acumen 3 A/T electrodynamic device, with a tri-axis 3 kN Kistler load cell mounted on a surgical tool was used to reproduce surgeon's gesture by moving at a constant rotational speed of 10°/mm and performing a three-section test. Perforation of the pedicle's cortical shell was planned through a design of experiment on the surgical tool angle at the entry point. Samples were scanned before and after mechanical tests and reproducibility of the protocol was tested on synthetic foam. Computation of the angle between cannulation tool and pedicle cortical shell was performed as well as cannulation coefficient of each perforation section. FindingsA total of 68 pedicles were tested: 19 perforated and 21 non-perforated human pedicles, 17 perforated and 16 non-perforated swine pedicles. The reproducibility of the protocol for cannulation coefficient computation resulted in an intraclass correlation coefficient of 0.979. Cannulation coefficients results presented variability within spinal levels as well as between swine and human model. Correlation between bone density and cannulation coefficient was found significant (p < 0.005). Torque measurement was found to be the best predictor of perforation. Threshold of angle for prediction of perforation was found to be 21.7°. InterpretationCharacterizing pedicle cannulation enables to predict extra pedicular perforation. Influence of bone mineral density and patient-specific morphology on pedicle cannulation has been highlighted together with a comparison of swine and cadaver models.

Suppressive effects of geotextiles on soil water evaporation

Geotextiles find wide applications in the field for filtration and drainage. When applied on the soil surface they influence soil evaporation. The objective of this work is twofold: (a) to assess the effectiveness of four different geotextiles as cover materials on soil evaporation, (b) to study the combined effect of geotextile and perforated mechanical barriers on soil evaporation. The first set of experimental programs consisted of three soil samples i.e. kaolin, dredged mud from the port of Brisbane and a locally obtained red mud sample from Queensland, Australia tested with four types of non-woven geotextiles under four controlled climatic conditions. All the 4 geotextiles had suppression effects on soil evaporation to degrees that varied with the type of soil, ratio of pore size to thickness of geotextiles (M*), product of pore size to thickness of the geotextiles (N*) and climatic conditions. Geotextiles with a higher pore size (O95) and M* allowed water vapor to move through relatively easily leading to higher evaporation rates. Geotextile with a higher thickness and N* value provided a higher suppression effect on soil evaporation. In a recently introduced dewatering method involving perforated ventilated well method, evaporation from soil take place through geotextiles and the perforated well. Mimicking this, impacts on soil evaporation with geotextiles sandwiched between soil sample and perforated sections were also studied. Maintaining similar number and arrangement of the perforations, soil evaporation was noted to be higher with rectangular shaped perforation compared to circular shaped perforations.

The numerical assessment of stress distribution of I-beam with web opening

PurposeCastellated and cellular beams achieved the same strength as solid I-beams with the same depth, resulting in significantly lighter and more economical structures. The purpose of this study is to analyse the bending behaviour of I-beam steel sections with certain web openings by finite element analysis.Design/methodology/approachThe accuracy of finite element results allows extensive numerical analysis of sections with web openings, concentrating on the web opening sizes and web opening positions. These assumptions can increase the induced section load with various shapes of web opening depth and web opening shapes of c-hexagon, hexagon, octagon, circular and square. This also includes spacing distances, with a 50-mm edge and 150-mm centre-to-centre distance and a section with a 100-mm edge and 200-mm centre-to-centre distance. Generally, the adjustment of the opening geometry (by reducing the angle of web pitch or reducing the opening depth depending on analysed parameters) may influence the bending behaviour.FindingsAdditionally, Model 2 was found to be the optimum model compared to Model 1, mainly in terms of bending. Moreover, the I-beam with a c-hexagon shape opening exhibited the lowest displacement compared to other sections with other web opening shapes. Section with a different arrangement of web opening, Type E shows the lower displacement while higher displacement is observed for Type A and also higher displacement considered for Type G. The optimum model is associated with Type E, followed by Type D, compared to other types of certain web opening and I-beam.Originality/valueThe use of sections with different arrangements of web opening improved the performance of the perforated section in terms of structural behaviour, compared to typical I-beam, thus leading to economic design.

Evaluation of the interaction between distortional–global buckling in perforated cold-formed steel rack sections

Storage systems are typically designed using cold-formed profiles, with the columns of the system consisting of rack-type sections perforated along their entire length. These columns are subjected to compression, and their failure can be caused by local, distortional, or global instabilities, which can act individually or in combination, resulting in local–global (L–G), local–distortional (L–D), distortional–global (D–G), and local–distortional–global (L–G–D) interactions. However, the interactions with distortional buckling are not yet fully understood, particularly in the case of rack sections with perforations. Unlike cold-formed profiles without holes, which are covered by standards and can be calculated by analytical methods, rack sections with perforations always require testing, and no analytical procedure is recommended. Therefore, an extensive parametric study developed through numerical simulations via ABAQUS software was performed to evaluate the interactions between D–G-type buckling in perforated rack profile columns. A total of 3055 post-buckling analyses were developed with previously selected columns via buckling analysis, where D–G interactions were verified. Finally, the direct strength method (DSM) was used, and its results were compared with those obtained by non-linear analysis. The DSM presented significant variability in the results, and a new DSM-based equation was proposed for each boundary condition.

Improving production and prediction of the flow regimes, pressure drop, and void fraction in the perforated horizontal wellbore

This study aimed to investigate how oil production could be improved by experimenting with different distribution methods across multiple profiles. The authors tested five different profiles that included uniform radial airflow (explained in profile 1) and variable radial airflow (explained in profiles 2, 3, 4 and 5) in a perforated horizontal wellbore. In addition, the study predicted the behavior of total pressure drop, superficial mixture velocity and void fraction encountered in different flow patterns (bubble, slug, stratum and stratum wave flow). Flow patterns were predicted using ANSYS Fluent R3 with a borehole length of 3 m and an ID of 0.0381 m. This was designed with 12 perforations opening vertically at the wellbore with a phase angle of 180 and a perforation density of 4 shots per foot to simulate the complex flow in a horizontal wellbore. In the perforated section, there was a fluctuation in the behavior of the parameters, while in the non-perforated section, the behavior remained constant. The behavior of the total pressure drop, the superficial velocity mixtures and the void fraction were also reasonably uniform in profile 1 in the perforated section.In contrast, they were irregular in the other profiles. In profiles 2, 3, 4 and 5, the behavior of the mixture superficial velocity and void fraction was inverse to the total pressure drop. Note that all theoretically calculated pressure drop modes increased as the Reynolds number of the mixture increased. The liquid and air product increased with increasing Reynolds number of mixture flow in the profiles. In contrast, in profile 1, lower production was obtained through all flow patterns due to the influence of the mixture pressure and the friction factor. The Vogels method was used to calculate maximum production from the horizontal wellbore. The convergence between experimental and numerical results was good during all cases (flow patterns), with some difference in the static pressure drop behaviuor occurring during flow patterns (bubble, dispersed bubble and slug flow).

The magnitude of stress concentration of I-beam with web opening because of lateral-torsional buckling effects

PurposeIt is generally known that the perforated section such as the castellated section is good to sustain distributed loads but inadequate to sustain highly concentrated loads. Therefore, it is possible to design the opening in a different arrangement of web opening to achieve section efficiency, thus improving the strength and torsional behaviour of the section with web opening. This study aims to focus on the finite element analysis of I-beam with and without openings in steel section dominated to lateral-torsional buckling behaviour.Design/methodology/approachIn this work, the analysis of different sizes, shapes and arrangements of web opening is performed by using LUSAS application to conduct numerical analysis on lateral-torsional buckling behaviour. This involves three diameter sizes of web opening, five types of opening shapes and two criteria of the model.FindingsThe section with c-hexagon web opening was placed about 200-mm centre to centre and 100-mm edge distance, contribute to 7.26% increase of buckling capacity. For the section with 150-mm centre to centre and 50-mm edge distance, the occurrence of local buckling contributes to decrease of lateral buckling section capacity to 19.943 kNm, where pure lateral-torsional buckling mostly occurred because of prevented section. Besides that, the web opening diameter was also analysed. The web crippling was observed because of the increase of opening diameter from 0.67 to 0.80 D.Originality/valueThis contributes to a decrease in buckling capacity as figured in the contour of the deformed shape. For Model 1, an increase of buckling capacity (31.46%) is observed when the opening diameter are changed from 0.67 to 0.80 D.

Sectional capacities of cold-formed perforated steel channel columns

Holes are pre-punched in the web of cold-formed steel channel columns to accommodate the technical systems. Many research studies have considered and illustrated the impacts of web holes on the capacities of such steel channel columns. These impacts have been accounted for in the American Specification AISI S100-16 using a new design method termed as the Direct Strength Method (DSM). This method allows designers to predict the capacities of cold-formed steel members on the basis of elastic buckling analyses. These analyses can be carried out by using a new module software package CUFSM recently developed by The American Iron and Steel Institute to analyse the buckling behaviors of cold-formed steel sections with perforations. This paper is aimed to apply the DSM to investigate the sectional capacities of cold-formed steel channel columns with a variety of hole dimensions. The behaviors and strengths of these perforated steel channel sections are analysed; recommendations are subsequently provided for the optimum of capacities in terms of the same hole areas. It was found that perforated channel columns with smaller heights and longer lengths are more beneficial for sectional capacities in general. .

Nonlinear Seismic Analysis of Perforated cold-formed steel shear wall with Upright Section

During the last few decades, cold-formed steel (CFS) is extensively used in mid- and low-rise housing due to the increasing demand of rapid constructions along with its various advantages in comparison with other structural material. Cold-formed steel framed shear walls (CFSFSW) are most common and primary lateral load resisting system. However, adopting it in the seismic zone is difficult, especially because many design components remain open. In this research an effort has been made to design the shear wall system with both unperforated and perforated upright sections using nonlinear static analysis method. In ABAQUS, a general-purpose finite element analysis software, three-dimensional models using shell elements are used to simulate a shear wall system. A comparative study regarding the lateral load capacities with respect to maximum allowable lateral deflection including different parameters like column sections, thickness and perforation arrangements are presented here. It was found that increasing thickness and including Chanel stiffeners improves the lateral strength of original upright section. The developed modelling protocol helps to estimate its lateral performance under earthquake with reasonable accuracy.