Perforated Section Research Articles

Investigation of sectional capacities of cold‐formed perforated steel channel sections

AbstractWeb holes are commonly seen in cold‐formed steel channel sections to accommodate the technical services. The presence of the web holes has resulted in the reduction of the sectional capacities of the cold‐formed steel sections and has been considered in the design according to the American Specification AISI S100‐16 using a new approach in the design called the Direct Strength Method (DSM). This article, therefore, will use this design method to investigate the sectional capacities of perforated channel sections under compression or bending with the variation of hole sizes in relation to those of gross channel sections. Elastic buckling analysis – a compulsory requirement for application of the DSM – can be conducted using a module CUFSM software program recently developed by the American Iron and Steel Institute. The investigated channel sections are taken from the availably commercial sections. The obtained sectional capacities are seen as the opposite trends for local and distortional buckling modes, although a downtrend of the sectional capacities is found in general with the increase of hole dimensions. It was found that perforated channel sections with smaller hole height and longer hole lengths were recommended to obtain the optimum section capacities in terms of the same web hole area, but the opposite trend was seen for these sections under bending with long hole lengths.

Experimental Investigations of the Behavior of Stiffened Perforated Cold-Formed Steel Sections Subjected to Axial Compression

Cold-formed steel sections are becoming popular for different steel structures, because they have a high resistance against different straining actions, with a minimal weight compared with hard steel sections. Recently, perforated cold-formed steel (PCFS) sections have been used in many applications, such as perforated upright storage racks. Experimental research into the behavior of steel storage rack uprights subjected to axial compression is presented in this paper. First, tensile tests determined the material qualities of the cold-formed steel uprights. Then, seventeen perforated specimens were examined under axial compression, with five different cross-sections, three different web heights and thicknesses, and varying lengths. The study’s goals were to find out how perforations affect the performance and failure mode of steel storage rack uprights, to discuss the interaction of distortional and global buckling, and to verify the accuracy of using the direct strength method (DSM) for predicting the ultimate strength before failure in buckling interactions for perforated uprights. It was found that the failure modes of perforated specimens with stiffeners generally cannot be well predicted using the direct strength method. However, when the modifications proposed by Xianzhong Zhao et al. are used, the accuracy is acceptable.

Importance of abdominal X-ray to confirm the position of levonorgestrel-releasing intrauterine system: A case report

BACKGROUNDLevonorgestrel-releasing intrauterine systems (LNG-IUSs) gradually release levonorgestrel into the uterus and is effective against hypermenorrhoea and dysmenorrhea. Complications associated with the insertion include expulsion, displacement, and uterine perforation. Ultrasonic identification of copper intrauterine devices (IUDs) is possible due to echogenicity from the copper coils. However, the barium sulfate coatings of LNG-IUSs do not always provide hyperechoic images. Both barium sulfate and copper are radiopaque and clearly identifiable on X-ray. Thus, X-ray imaging is required to locate LNG-IUSs.CASE SUMMARYA 46-year-old woman with hypermenorrhoea due to submucosal myomas was treated with LNG-IUS at another hospital. Three LNG-IUS insertions had apparently been followed by spontaneous expulsion, although objective confirmation using imaging was not performed. The patient was referred to our institution for surgery. At the first visit, there appeared to be no device in the uterus, and none was observed on transvaginal ultrasound. However, two LNG-IUSs were observed in the pelvis on abdominal plain X-rays prior to surgery. Hysteroscopic myomectomy was performed, and the two LNG-IUSs were found to have perforated the myometrium. The devices were safely removed during surgery, and the submucosal myomas were also removed. The perforated section of the myometrium was minimal+ADs- therefore, a repair operation was not required.CONCLUSIONPlain abdominal X-rays facilitate the determination of whether an LNG-IUS is in the uterine cavity. Therefore, it is important to confirm a device’s location, regardless of whether spontaneous expulsion is suspected, prior to inserting another device.

Elastic Buckling Loads of Cold-Formed Steel Channel Sections with Perforations

Cold-formed perforated steel sections have been commonly applied to meet the demands for technical installations, leading to the reduction of capacities of these such sections. The capacities of these sectional types have been considered in the American Specification AISI S100-16 using the Direct Strength Method (DSM). This method known as the innovative method for the design of cold-formed steel sections allows predicting the sectional capacities of perforated sections based on elastic bucking loads. Elastic buckling analyses are compulsory for the application of the DSM in the design. The determination of elastic buckling loads of perforated sections is cumbersome with the usage of current buckling analysis software programs. The paper, therefore, presents a simple method for the determination of elastic buckling loads of cold-formed perforated channel sections, especially the paper is aimed to introduce a module software program used for elastic buckling analyses of these such channel sections based on this simple method. This program is convenient for buckling analysis, and it becomes a key program for the application of DSM in the design of cold-formed perforated steel channel sections. This software program is subsequently utilized to investigate the effects of web hole dimensions on the elastic buckling loads of cold-formed steel channel sections with perforations under compression or bending. The investigated results provide fundamental understandings of the buckling behaviors of perforated channel sections due to the effects of the web holes.

Effect of web perforation on the performance of pultruded GFRP wide-flange section profile in web crippling under end-two-flange loading configuration

The present study extensively investigates the performance of GFRP pultruded members in web crippling subjected to end-two-flange (ETF) loading configuration considering wide-flange (WF) section profile with circular perforation. Investigation comprised material characterization experiments as well as web crippling tests conducted on 15 specimens with unperforated and web perforated sections. In order to investigate the influence of perforation size, perforation dimensions were varied in the range of 0.2h to 0.8h (h is the height of web). In comparison to unperforated specimen, the ultimate crippling capacity of perforated specimens with diameters of perforation 0.2h, 0.4h, 0.6h and 0.8h were decreased by 26.0%, 43.2%, 61.6% and 78.3%, respectively. Finite element (FE) studies were also conducted and parametric investigation was performed by utilizing the validated FE models, to assess the influence of N/h and a/h ratios (N is length of bearing and a is perforation diameter) on the ultimate crippling load. Using the results of parametric investigation, strength reduction factor equation was developed for perforated GFRP WF-section profiles under ETF loading and suitability of the equation was examined with reliability analysis.

Web crippling behavior of perforated cold-formed Z-sections under end-two-flange loading

This paper aims to evaluate the web crippling behavior of the perforated cold-formed Z-sections subjected to web crippling under end-two-flange (ETF) loading. Perforated cold-formed sections are commonly used in the modern construction industry. North American Specification provides web crippling capacity for perforated C-sections under one flange load case only. Hence, a web crippling investigation for perforated Z-sections is conducted in this study. The nonlinear finite element models were developed for perforated Z-sections having centred beneath the web opening. Available experimental results from the literature are used to validate the nonlinear finite element model. Finite element models are validated for both solid web sections and perforated sections. The validated nonlinear finite element (FE) models are used to investigate the effect of web opening on the web crippling behavior of Z-sections with various web opening sizes varies from 20 to 80% of web height. The web crippling capacity of the perforated Z-sections obtained from the nonlinear finite element analysis is compared with the web crippling capacity of solid web sections. After the comparison, a suitable reduction factor equation is suggested for the perforated Z-section under end-two-flange loading.

Finite Element Analysis of Perforated Cold-Formed Steel Section: Effects of Shear Behaviour

This paper presents a numerical study on the shear behaviour of the steel framing system using a perforated section. The perforated steel section has a lower volume of steel, which causes the weight to decrease and lead to lower construction costs. However, perforation insteel will decrease the shear resistance of the steel framing system. The objective of this study was to investigate the shear behaviour of the perforated steel section comparing to the unperforated section in the steel framing system. Critical shear loading from a common steel framing system was obtained using Staad Pro software according to Eurocode Standard. Finite element analysis was performed and the structure capacity results were compared by using eigenvalue. Comparison were made between perforatedsections and unperforatedsection in term of shear capacity and percentage of volume reduction. Perforation steel section with 8 diamond openings was selected with the percentage of shear buckling capacity difference from an unperforated section about 33.02% and 48.18% with circleopenings. Shear buckling capacity reduced with the increasing number of web openings. Edge distance also affected the shear behaviour of plain channel section with web openings.

Flow control by distributed suction behind three-dimensional roughness element on the straight wing model

The paper is devoted to the close investigation of the flow over perforated suction section in the presence of the three-dimensional roughness element. Measurements were conducted over the surface of the straight wing with and without suction. It was shown that distributed suction allows diminishing the intensity of longitudinal structure. Also the boundaries of the effective suction usage were found.

Hydraulic fracturing fracture propagation in tight sandstone reservoir

The tight sandstone reservoir of Shaximiao Formation of Middle Jurassic in Qiulin block of central Sichuan Basin, with a burial depth about 2200 to 2300 m, is characterized by undeveloped natural fractures. It is difficult to form complex fracture network during the implementation of traditional volume fracturing technology, affecting the benefit of tight sandstone gas development. A series of true triaxial hydraulic fracturing tests were conducted on the sandstone outcrop (dimensions: 300 mm × 300 mm × 300 mm), collected from this block, to investigate the initiation and propagation law of hydraulic fracture in tight sandstone reservoir under different conditions. Experimental results indicate that the peak value disturbance and increasing stress shadow in the back section of the pump pressure curve of staged multi-cluster fracturing in horizontal wells of sandstone reservoir will dominate the fracture morphology. The small interval leads to the increase in dynamic hydrostatic pressure on the fracture wall and increase in the deflection angle and degree of multi-cluster fractures, and it is easy to form crosscut fractures. The symmetrical middle segment perforation cluster inhibits the initiation and expansion of fractures, and the fractures will extend perpendicular to the maximum horizontal in situ stress direction and gradually approach the fractures on both sides and finally stop expanding. High-viscosity fracturing fluid is easy to form high hydrostatic pressure in the perforated section, reducing the difficulty of fracture initiation. The angle between the borehole and the minimum horizontal in situ stress ( σ h) will affect the propagation direction of hydraulic fractures. When the angle is large, the propagation direction of fractures is easily affected by the natural weak surface and induced stress field, resulting in fracture diversion. This study has mastered the initiation and propagation mechanism of artificial hydraulic fractures in tight sandstone reservoir, established the optimization chart of fracturing parameters in sandstone reservoir, and has certain guiding significance for the establishment of on-site fine optimization fracturing scheme design.

Optimization of Gravel Pack Design in Long Perforation Section of Offshore Oil Field

Optimization of Gravel Pack Design in Long Perforation Section of Offshore Oil Field

Web crippling behaviour of web perforated GFRP wide-flange sections subjected to interior-two-flange loading condition

In this paper, an extensive study on the web crippling behaviour of GFRP wide-flange (WF) section profiles with centred web perforation under interior-two-flange (ITF) loading is reported. Experimental investigation included material characterization tests and full scale web crippling experiments performed on 14 specimens with and without web perforations under ITF loading configuration. To examine the effect of web perforation, perforation sizes were varied between 0.2h and 0.8h (h being the web height). Compared to the intact specimens, the average web crippling strength for perforated specimens with web perforation sizes 0.2h, 0.4h 0.6h and 0.8h was reduced by 14.7%, 22.2%, 24.2% and 41.1%, respectively. Numerical investigations were carried out using the finite element (FE) software, Abaqus and based on validated FE models, parametric studies were performed to study the effects of perforation diameter to web height ratio (a/h) and bearing plate length to web height ratio (N/h) on the web crippling strength. Based on the parametric study, web crippling strength reduction factor was proposed and its suitability was checked with reliability analysis.

The impact of closed perforation zones and damaged sections on flow dynamics and pressure behaviors of horizontal wells

Horizontal wells with multiple completion parts have become a common completion technique in the oil and gas industry. Sand and asphalt production problems, damaged zones and water cresting or gas coning are the main reasons for using this technique to sustain or improve oil and gas recovery. However, using such completion technique introduces negative effects on pressure behavior of horizontal wells.This paper introduces new mathematical models for horizontal well containing several closed completed sections acting in finite and infinite reservoirs. These models can be used to evaluate the impact of the completion techniques on both pressure behaviors and flow regimes either in the vicinity of wellbore or at the outer boundary of reservoirs. They can be used also to investigate the change in productivity index that would result due to the usage of certain type of completion technique. In this research, the completed sections (cemented or isolated parts) and the places where packers are installed are considered as no-flow sections. These sections are expected to increase pressure drop required for flowing reservoir fluid toward wellbore. They are also expected to change flow regimes mainly in the vicinity of wellbore.Several models have been developed and solved in this study for different completion techniques, wellbore conditions and reservoir configuration. It has been found that the great impact of completion techniques is observed on flow regimes that commonly develop in the drainage area close to wellbore. This impact shows similar trends to the skin factor. Several new flow regimes have been observed, one of them has been developed due to the existence of closed completed sections which is intermediate or second radial flow regime. This flow regime can be found for some cases of long wellbore having multi-short perforated sections. The study will introduce the mathematical models for known and newly developed flow regimes for horizontal well including the completion technique.

A numerical study on structural behaviour of lean duplex stainless steel tubular beams with rectangular web openings

This paper investigates the flexural behaviour of Lean Duplex Stainless Steel (LDSS) rectangular tubular beams with rectangular web openings located centrally. The analysis procedures for the FE models were verified by validating with test results conducted by different authors for the perforated open sections as well as unperforated tubular sections. In order to study the effect of perforation on the structural response of Rectangular Hollow Sections (RHS), rectangular perforation is chosen with steel tube thicknesses ranging from 0.8 mm to 3.0 mm. It is observed that there is a linear decrease in moment capacities of the section with increase in the size of openings with local buckling being more predominant in the case of slender sections as compared to the stocky sections. The section capacities obtained were compared with the design strength calculated against the EN1993-1–4 (2006), ASCE8-02, the direct strength method (DSM) and the continuous strength method (CSM). The design strength calculated for perforated beams with respect to the CSM method gave the best predictions for strength calculation.

Numerical Analysis of Casing Damage in Heavy Oil Thermal Recovery Wells

With the decrease in the world’s thin oil resources, heavy oil resources gradually become the main resources in the current and coming period. However, the casing damage of thermal recovery wells seriously restricts the development and exploitation of heavy oil. By investigating geological conditions, production status, and casing damage from in Liaohe Oilfield, the mechanism of casing damage in heavy oil thermal recovery wells was analyzed. Through establishing a casing-cement sheath-formation model and using a thermosetting coupling model of transient heat transfer, the temperature field and stress field of casing in the perforation section were simulated and studied, and the influence law of thermal stress generated by high temperature on the casing was analyzed. The damage of perforated casing is mainly caused by thermal stress, making the casing bear the alternating load of high temperature and high pressure, research shows. After multiple rounds of steam huff and puff, the residual stress of casing increases with the period, resulting in casing fatigue failure. Meanwhile, sand production seriously abrades casing, causing stress concentration of casing and then accelerating casing damage. By studying the casing optimization design, the occurrence of casing damage in heavy oil thermal recovery wells can be reduced and even prevented.

ANALYTICAL STUDY OF FLEXURAL BEHAVIOR OF COLD FORMED STEEL SECTIONS WITH AND WITHOUT PERFORATION

This work is about the investigation of flexural behavior cold formed steel member of different cross sections with and without perforation under similar cross sectional area. This work gives idea about the performance of different sections under same loading condition among selected sections and highlights the increasing the flexural strength of member by using stiffener arrangement. In this work three different cross sectional shapes are selected which are C – section, Z – section and Hat shaped section of same cross sectional area analyzed with and without lip under same loading and end condition as well as with perforation. The selected specimens were analyzed analytically using ANSYS Workbench software which shown better comparison among analyzed different geometries of members. Effectiveness of providing edge stiffener to different perforated sections also determined in this work.

Circular perforated steel yielding demountable shear connector for sustainable precast composite floors

A circular steel-yielding demountable shear connector is proposed. The connector consists of a short perforated circular hollow section (CHS) welded on a base plate which in turn is bolted on the top flange of a steel section. The connector provides longitudinal shear resistance in all directions through yielding of steel and is used in conjunction with precast hollow core slab units. The mechanical behaviour is first studied using a previously validated detailed finite element model simulating horizontal pushout tests, by conducting a series of parametric studies to identify all failure modes of the novel connector. Based on the results of the numerical pushout tests, design equations to predict the strength of the connector are proposed. A composite beam using hollow core slabs and various degrees of shear connection is then simulated to verify the applicability of the circular connector and the implications in the design of composite beams.

Перфорація стравоходу у тварин та методи їх лікування (клінічний випадок)

The purpose of the work was to research the etiological factors of perforation of esophagus, the clinical condition of animals, and also to perform a technique for surgical intervention to restore the function of the esophagus. The technique of operative access and the imposition of strong, airtight sutures was developed to contribute to the restoration of the esophagus function. The investigation object was three goats with bitten lacerations complicated by perforation of the esophagus in the cranioventral part of the neck, a horse with perforation of the esophagus in the middle part of the neck. The operating field in animals with damage of esophagus was prepared taking into account mechanical and chemical antiseptics, and local infiltration anesthesia was performed. The necrotic edges of the wounds excised, the skin dissected by 12-15 cm, and the neck muscles moved and separated in relation to each other, fixed with wound hooks and provided access to the perforated section of the esophagus. On the detected defects of the esophagus a polymer tube inserted into the cavity of the esophageal tube through the wound openings in the cranial direction until it exited the oral cavity by 10-15 cm, and then along the esophagus, than shifted towards the stomach. Thus, we obtained such a configuration and clear contours of the esophagus, which would facilitate the possibility of controlling the layer-by-layer application of surgical sutures and closing the perforation of the esophageal walls. The first level of Schmiden sutures applied to the mucous and muscle layers. Subsequently, for reliability three intermittent knotted seams imposed on the same layers. The second floor of the sutures – intermittent knotty was placed on the muscles and the adventitious layer of the esophagus (polymer suture material No. 4-6). Thus, a hermetic closure of the perforated defects of the esophagus was achieved. The wound was treated with antibacterial drugs and, first, an interrupted knotted suture was placed on the muscles and then on the muscles and skin. The resin tube removed through the oral cavity. In the postoperative period the neck was restricted in movement by applying wooden corsets for 5-6 days. The wound was treated with antibacterial drugs for 7 days. Feeding was carried out with chopped food, watering in small doses for two weeks. Regeneration of the operating wounds took place without complications due to primary intention. In 6-8 weeks after surgery the clinical condition of the animals was within normal limits, the animals were fed normally.

Buckling capacity of cold-formed steel structure column member with perforation section in affordable house framing system

PurposeThe purpose of this study is to know the buckling capacity for cold-formed C-column with perforation. Cold-formed C-column have been used in interior wall construction. The concept of web perforation in the column has been introduced to the construction sector to overcome the issue of material cost.Design/methodology/approachInitially, the determination of the suitable spacing for the space column for the affordable house is investigated. Analysis house frame has been done in STAAD Pro. (Staad Pro, 2003) software using cold-formed C-column without perforation. Perforation with circular shape has been used in this study with the size of 0.4, 0.6 and 0.8 D (D = 180 mm). Perforation spacing is 150, 250 and 350 mm are adopted.FindingsFor the specimen with 0.4 D perforation and the edge distance is 539 mm have the highest buckling capacity (26.59 kN). Reduction of buckling capacity is 5.31% from cold-formed C-column without perforation and reduction of the volume is −2.16%. For the same case with 0.8 D perforation, the buckling capacity reduces with 22.52% and volume is −6.85%.Originality/valueThe conclusion of this analysis, C-column without perforation have higher buckling capacity compare to C-column with perforations.

Anti-collapse performance of steel frames with RWS connections under a column removal scenario

The spread of an initial local failure from load-carrying member to other members in system when subjected to abnormal load, eventually resulting the progressive collapse of an entire structure. This paper presents an experimental and parametric study on the anti-collapse performance of moment resisting frames (MRFs) with reduced-web-section (RWS) connections under critical column removal scenario. Factors influencing robustness and rotational capacity in these connections under Vierendeel failure are analyzed. A total of 14 laboratory tests on steel beam-column connections with complete joint penetrations are presented; one test was conducted with solid beam connections, while the others were designed to have RWS connections with different circular web openings geometric parameters. Comprehensive finite models are then implemented to further interpret the obtained test results. The test results demonstrated that vertical resistance against the applied load atop the failed columns was totally composed of flexural action (FA) in the early stages, and it became catenary action (CA) as the vertical displacement of the failed column increased. There are two typical failure modes, continuous failure in the beam-column joint region generated by the weld line fracture and interrupted failure in RWS connections generated by the fracturing of a perforated section, and the different failure modes determine whether the system can develop meaningful catenary action when the initial fracture occurs. Specimens with openings exhibited multiple peak loads because of the repeated occurrence of local damage in the beam-column connection. RWS connections with local failure near the openings were capable of developing deformability and resistance associated with CA when the dimensions and location parameters of the opening are controlled within a suitable range, and the rotational capacities of these connections were larger than the connection with solid beams.

Finite-element modelling and design guidelines for axial compressive capacity of aluminium alloy circular hollow sections with holes

This paper presents a finite-element (FE) investigation on the axial compressive capacity of aluminium alloy circular hollow sections (CHSs) with circular holes. The geometrical and material non-linearities were considered in the finite-element analysis (FEA). Two consecutive steps including an eigenvalue analysis and a load-displacement non-linear analysis were performed in the FEA. The FE models were validated against the test results reported by the first author in a previous study. The validated FE models were used to conduct an extensive parametric study comprising 300 FE models, to investigate the effects of five geometrical parameters on axial compressive capacity: the wall thickness, overall length, the diameter, and the quantity and location of the circular through-holes. In addition, a comparison was performed between the FEA strengths and design strengths calculated using the design formulae of American Design Manual (AA), European Code (EC9), Australian/New Zealand Standard (AS/NZS), Chinese Code for imperforated members, and North American Specification (NAS). Moreover, the FEA strengths were compared against the design strengths calculated from the proposed design guidelines of Dhanalakshmi and Shanmugam, Shanmugam et al., Shanmugam and Dhanalakshmi, and Moen and Schafer for cold-formed steel (CFS) sections with holes. The comparison of design strengths against FEA results showed that the current design formulae for CFS perforated sections are not suitable for aluminium alloy CHSs with circular holes. Therefore, new design equations were proposed based on the current design formulae that use effective area method (EAM) by considering the influences of key geometrical parameters.