Horizontal Stiffeners Research Articles

Numerical investigation on effects of steel I-section beams on the blast resistance of a stiffened steel tank under blast loading

The hazardous chemical storage tank faces a vital explosion risk, making reliability a critical concern. This study investigates the horizontal stiffening ring as an effective anti-blast measure to enhance the reliability of steel tanks under explosive conditions. Through numerical examination based on CONWEP model, we assessed the impact of vertical spacing between adjacent horizontal stiffening rings and their dimensions on the tank's blast resistance and overall structural integrity. The results suggest that a marked improvement in the tank's reliability and blast resistance with the addition of stiffening rings as horizontal stiffeners. The deformation shapes of the stiffened steel tank were less pronounced, and the radial displacements were smaller compared to an unstiffened steel tank. Additionally, the addition of horizontal stiffening rings enhanced the overall stiffness and stability of the steel tank. Furthermore, larger beam dimensions contribute to increased bending and shear stiffness, resulting in smaller deformations and better blast resistance of the steel tank.

Finite element analysis on composite steel-concrete shear walls with centered and staggered openings

Present paper presents a comparative study made on the seismic performance of composite steel-concrete shear walls with rectangular openings, by performing numerical analyses using ATENA 3D software. Two specimens were designed at a reduced scale 1:3 having similar arrangements in the cross-section and the same geometry. First element was conceived with centered openings while the second one was designed with staggered openings. Steel connectors disposed as horizontal stiffeners were used to design and to assure the full connection between the structural steel profiles embedded in the edges and the concrete core. The openings that were considered on each story of the walls, were having the dimension of a common architectural door. A part of the results recorded from the experimental tests were used to calibrate the numerical models. This study aims to establish the seismic performance and to investigate the influence of the openings and the geometric position on the overall seismic behavior of the composite shear walls. Key parameters which describe the seismic performance of structural elements such: bearing capacity, deformation capacity, stiffness degradation, cracks and strain development are compared between the specimens and discussed. The results showed that different arrangements of the openings could significantly modify or increase the seismic performance of the composite structural walls.

Design of precast UHPFRC retaining walls – Experimental and numerical validations

This paper focuses on the design as well as on the experimental and numerical validations of the mechanical behavior of a precast ultra-high performance fibre reinforced concrete (UHPFRC) retaining walls. The design, made in accordance with the Canadian Highway Bridge Design Code ( CSA S6, 2019 ), led to the fabrication of a full-scale UHPFRC retaining wall with 3% fibre content which had dimensions of 3 m in height, 2 m in length, 2 m in width, with two vertical and horizontal stiffeners, and very thin vertical and horizontal panels of 40 and 65 mm, respectively. The experimental tests showed that the UHPFRC retaining wall exceeded by 42% the ultimate limit state (ULS) design factored bending moment and showed a very ductile behavior under flexural loading. At service limit state (SLS), the retaining wall had maximum crack opening between 0.15 and 0.28 mm, and a maximum lateral displacement of 4 mm. The finite-element model developed for the application captured accurately the flexural behavior of the UHPFRC retaining wall and was used later in parametric studies to optimize the design. The retaining wall optimal design includes UHPFRC with 3% fibre content and stiffeners with variable cross-section which allows volume reductions of 73% for concrete and 86% for rebars in comparison to the conventional reinforced concrete design.

Axial compressive behavior of high-strength concrete-filled steel tube with multiple confinement effects

To study the axial compressive behavior and the confinement mechanism of high-strength concrete-filled circular steel tube with multiple confinement effects, five large size samples with horizontal stiffeners, longitudinal stiffeners, multilayer reinforcement cages, inner steel tube and separation steel plates were designed. The influences of these structures on the bearing capacity, ductility, stiffness, and residual deformation were then analyzed. Combining the strain analyses and finite element model analysis, the confinement mechanism of different structures and the coupling mechanism of different confinement effects were investigated. The results showed that the confinement effect of the horizontal stiffeners was similar to that of the stirrups. The longitudinal stiffeners did not provide a significant confinement effect on the concrete. The multilayer reinforcement cages had an effective confinement effect on the concrete, where the confinement effect increased from the outside to the inside, while the reinforcement cages had a slight influence on the concrete outside the reinforcement cages. The inner steel tube had an effective confinement effect on the core concrete and had a slight influence on the concrete outside the inner steel tube. The multicell steel tube showed the best confinement effect compared to the other structures and showed the best axial compressive behavior. In the confinement mechanism analyses, the calculation method of the stress–strain relationship of concrete with multiple confinement effects was proposed. The calculated F-Δ curves showed a good agreement with the test results.

A Horizontal Stiffener Detailing for Shear Links at the Link-to-Column Connection in Eccentrically Braced Frames

This study investigates the performance and viability of a horizontal stiffener detailing (HSD) to (1) be used at the link-to-column connection in a D-braced eccentrically braced frame layout where conventional link-to-column connections show poor performance, (2) minimize the overstrength factor of shear links caused by the hardening of link flanges, and (3) mitigate an undesirable failure mechanism previously observed in shear links fabricated using ASTM A992 steel. HSD and conventional stiffener detailing (CSD) were tested using W460×60 sections under two loading protocols, including one simulating near-collapse excitation. While the flanges of CSD shear links are greatly stiffened by vertical stiffeners, webs of HSD shear links exhibit inelastic buckling at large rotation angles. This allows the flanges to freely deform, thereby reducing the likelihood of brittle fracture at the flange connections, as well as undesirable link overstrength induced by the flange contribution. This study shows that the horizontal stiffener configuration developed a ductile failure mechanism resulting from gradually increasing local buckling in the web. The strength degradation of links with horizontal stiffener detailing was much more gradual due to the ever-increasing web buckling, unlike the sudden brittle fracture at the flange-to-column face of links with CSD. This research shows that the HSD is a viable and economic alternative for shear links, which has the potential to decrease welding in the shear link while exhibiting adequate seismic performance. HSD also maintains a low overstrength factor and utilizes a simplistic design approach. Finally, the bolted extended end-plate connection and its details at the link ends used in the test experiment provided a viable solution for replaceable links.

Performance of vertically-placed stiffened corrugated panels in steel plate shear walls: Shear elastic buckling analysis

Adding horizontal stiffeners to vertically-placed corrugated panels is an effective way to improve their shear buckling strength. Since the shear elastic buckling loads (Ncr) of vertically-placed stiffened corrugated steel walls (VSCSWs) are related to their practical design, this study investigates the VSCSWs' shear elastic buckling behaviors and aims to determine the formulas for predicting the Ncr of VSCSWs. Firstly, the number of horizontal stiffeners required by VSCSWs is discussed utilizing the calculation model of VSCSWs’ shear elastic buckling load established based on the minimum potential energy and the Ritz method. Then, the shear elastic buckling behaviors of VSCSWs with one pair and two pairs of horizontal stiffeners are analyzed, and formulas for predicting their shear elastic buckling coefficients are proposed. Lastly, finite element shear elastic buckling analyses are conducted to verify the accuracy of the proposed formulas. It is found that the shear elastic buckling coefficient of VSCSWs first grows and then almost remains unchanged with the increased rigidity ratio of the stiffening system. It has been observed that the equations proposed are in good agreement with the numerical results and can be applied to the design of the VSCSWs.

Behaviour and Design of Innovative Connections of Prefabricated CFST Columns under Tension

This paper investigates the tensile behaviour of prefabricated concrete-filled steel tube (PCFST) columns with bolted connections. Innovative bolted column-column (BCC) connections are developed using standard structural bolts to simplify the construction process for the connection of two PCFST columns, especially for the corner, edge, and interior columns. The behaviour of BCC connections in PCFST columns under tension has been investigated, adopting the finite element (FE) modelling approach. Parametric studies are carried out to understand the influence of bolt arrangements (TB = 4, 6, 7, 8), base plate thickness (tbp = 8, 10, 14, and 18 mm), bolt diameters (db = 16, 18, 20, 24 mm), vertical stiffeners (ths = 4, 6, 8, 10 mm), horizontal stiffeners (ths = 10, 12, 13, 15 mm), and yield strength of steel tube (fy,t = 380, 450, and 550 MPa) on the behaviour of PCFST columns with developed BCC connections. The results show that the PCFST columns with the developed BCC connections can attain sufficient tensile strength and satisfy the tensile strength requirements recommended in AS5100 and the robustness requirements in AS1170. The outcome of this paper will be useful to practising structural engineers to design prefabricated CFST columns with BCC connections under tension.

Influence of Outrigger Systems on the Spatial Rigidity of an Object of Parametric Architecture

Introduction. In the existing building industry standards and regulations there are currently put into effect the requirements for the spatial rigidity of buildings and structures. For fulfillment of the set requirements various design solutions are used: outrigger systems, edge beams, subrafter constructions etc. Currently the most common design solution for high-rise buildings is integration of the outrigger systems into a building frame.Materials and methods. The evolution of forming the epicycloid cylindrical surface in the SAPPHIRE software was investigated. Based on the results of the study, the optimal form of a parametric architecture object was determined. Five versions of an object design solutions were developed. Modeling of the elaborated building frames was performed in the LIRA-SAPR software based on the slab-beam design model by the finite element method.Results. The analysis of static and dynamic calculations results enables to choose the rational version of a parametric architecture object frame and to provide the necessary strength attributed with maximum possible lean consumption of the materials for the outrigger storey. In the course of experiment the efficiency of a building frame dynamic properties regulation is defined, the technical and economic indicators of the proposed versions and design solutions aimed at increasing the overall rigidity of the building are compared.Discussion and conclusion. A comparative analysis of the dynamic properties regulation efficiency was carried out for each structural scheme. The most rational scheme for a high-rise building was selected, the one meeting the strength and rigidity requirements and proving to be the most material saving. In addition to the efficient dynamic properties regulation, the horizontal stiffening rings were implemented as a constructive solution to prevent and protect a high-rise building from progressing impact which accounts for complete or partial collapse of the building.

Loading test of full-scale composite plate girder with partial encasing

Plate girders have been extensively studied to propose improved or updated configurations for coping with instability as well as constructability problems. Yet, this study introduces a new configuration of the composite plate girder which encases the upper part of the steel plate girder in the concrete slab and the trimming of the upper outer corner of the vertical stiffeners to accommodate temporary cross-beams during the erection and ease the installation of forms without the need of propping. Rather than using corrugated webs, the proposed girder utilizes only flat plates to simplify its fabrication and allow camber to be provided through an automated manufacturing process so that high quality standards can be achieved. The proposed configuration has enough flexural buckling strength with minimum horizontal stiffeners and only 2 plate thicknesses, which promotes purchase efficiency of the steel plate and accelerates production of the girder. A 51 m-long full-scale composite plate girder was fabricated and subjected to fatigue test up to 2 million cycles followed by ultimate strength test. The prototype remained sound beyond the ultimate limit state and did not suffer any noticeable damage or loss of flexural rigidity until the end of the test. A finite element model was also established to overcome the limitations of the test facility and validate the design of the composite girder. The comparison of the experimental and analytical results revealed good agreement and demonstrated remarkable fatigue resistance. The proposed composite plate girder satisfied sufficiently the relevant design requirements.

Investigation on in-plane structural behavior of steel arches with rectangular web-openings

This study presents an experimental study and a finite element analysis of the in-plane structural properties of steel arches with rectangular web openings under static loading. The failure mode, deflection, section stress distribution, and other mechanical properties of three steel arch specimens with equidistant rectangular web openings are investigated. It is found that the ultimate load capacity, ductility, and stiffness of the steel arch decrease owing to large-scale openings compared with small-scale openings. The ultimate loading capacity and stiffness of the web-opening steel arches can be improved by welding stiffeners on the edge of the opening. In addition, 52 finite element models are established for parametric analysis to investigate the influence of the steel arch and stiffener geometries on the structural performance. The results show that increasing the rise-span ratio and web and flange thickness increase the ultimate loading capacity of the steel arch. A larger opening will cause the ultimate loading capacity and ductility to decrease significantly. The ultimate loading capacity of the steel arch is affected by horizontal stiffeners, whereas ductility is affected by both horizontal and vertical stiffeners. Finally, this study provides design recommendations to serve as engineering design references.

Hysteretic behavior of cold-formed steel reinforced concrete shear walls with steel meshes

To satisfy the requirements of hysteretic behavior of cold-formed steel (CFS) shear walls in mid-high buildings, a new type of cold-formed steel reinforced concrete (CSRC) shear wall with steel meshes on both sides is proposed in this study. Steel mesh is made of galvanized steel sheet by pressing holes, and there are horizontal ribbed stiffeners and rectangular grids arranged at equal intervals. Five full-scale specimens with different configurations were tested subjected to reversed cyclic loading to assess the failure mode, load-bearing capacity, ductility, lateral stiffness, energy dissipation and strain. The effects of the aspect ratio, the presence of horizontal reinforcing bars, the presence of X-shaped bracing, and the horizontal reinforcement ratio were analyzed. The results showed that the shear wall shows more pronounced flexural failure characteristics with the increase of the aspect ratio. Horizontal reinforcing bars could reduce the concentration of crack distribution and improve the shear capacity of the shear wall, whereas the increase of the horizontal reinforcement ratio from 0.35% to 0.65% had little effect on the hysteretic behavior of the wall in bending failure. The X-shaped bracing significantly improved the load-bearing capacity and moderated the pinching effect of the hysteresis curve before peak load, but reduced the ductility of the wall. Finally, the restoring force model based on the experimental data and theoretical analysis was established, and the hysteretic behavior of CSRC shear walls was well predicted.

Experimental and numerical study of concrete frames with steel plate shear walls

Steel plate shear wall systems have appropriate behavior in high seismic zones. They could be combined with concrete or precast concrete structures to compensate susceptibility of these structures to strong earthquakes. This article presents an experimental and numerical study on seismic behavior of various types of steel plate shear walls installed in simple and rigid concrete frames. These frames were subjected to quasi-static cycling loading in accordance with ACI T1.1–01. Compared to the bare moment frame, erection of the steel plate in simple concrete frame by bearing bolted connection led to an increase in lateral load capacity, initial stiffness, energy dissipation and equivalent hysteretic damping up to 1.7, 2.2, 3.5 and 3 times, respectively. These ratios for the steel plate shear wall with moment frame, and connected by friction bolted connections were 3, 7.2, 7.7 and 3.2 times. The horizontal and vertical stiffeners in the steel plate shear wall with the openings over the main diameters contributed to 13% and 27% increase in energy dissipation and equivalent damping, respectively, while the load bearing capacity and initial stiffness did not decrease significantly. At the bearing bolted connections, crippling and tearing of the steel plate was observed, but no any damage occurred at the friction bolted connections. Whereas, all the steel connecting components embedded in concrete were in the elastic range and also, equations governing the angle of inclination of the tensile field, were valid. Finally, the samples were simulated in Abaqus finite element software, and the pushover curves of experimental load-displacements diagrams were predicted.

Finite element modeling and behavior of dissipative embedded column base connections under cyclic loading

This paper explores, by means of continuum finite element (CFE) analysis, a recently developed concept that promotes controlled inelastic energy dissipation within the embedded portion of column base connections rather than in steel columns of conventional embedded column bases. As such, dissipative embedded column base connections become resilient to local buckling. Several loading and geometric parameters are interrogated through parametric simulations with a high-fidelity CFE model, which is thoroughly validated with available experimental data. The simulation results suggest that steel columns in conventional embedded bases are prone to local buckling even at modest lateral drift demands (i.e., 2% rad), thereby exhibiting 10 to 30 mm of axial shortening in the presence of constant compressive axial load. On the other hand, dissipative bases are resilient to local buckling till at least 4% rad lateral drift demands regardless of the column cross-sectional characteristics and loading parameters. At larger lateral drift demands, the use of horizontal stiffeners in dissipative bases alleviates localized flange deformations attributable to bearing of the embedded column flange with the reinforced concrete foundation. Axial shortening in dissipative base connections is only attributable to inelastic cyclic straining within the dissipative zone and is up to 60% less than that of steel columns in conventional bases at lateral drift demands of 2% rad. The CFE simulations reveal that the hysteretic response of dissipative bases is insensitive to bidirectional loading.

Seismic performance of thread-fixed one-side bolts bolted extended endplate connection to HSST column with internal strengthening components

This paper presents experimental results of the seismic performance of the Thread-fixed One-side Bolts bolted Endplate Connection to Hollow Square Steel Tube column (TOBEC-HSST) with internal strengthening components. Five specimens were tested under cyclic loading. The main variable parameters affecting the seismic behavior of specimens were the internal strengthening structure types (i.e. the polygonal steel tube without inner stiffener, or with the horizontal or vertical stiffener) and the extended endplate types (i.e. with or without the endplate stiffeners). The failure modes of connections were observed, the moment-rotation hysteretic response and the strain distribution of connections were obtained. Besides, the rotation ability and ductility, the degradation of strength and rigidity, and the energy dissipation capacity were analyzed and compared, which were affected by the strengthening measures. The introduction of the endplate stiffeners can improve the overall rigidity of the joint region and sufficiently develop the energy dissipation capacity and ductility of the connections, and the contribution from the inner stiffener in the internal strengthening polygonal steel tube can also enhance the seismic performance of the connections. In addition, the rotations at the failure of the connection were larger than 30 mrad, which satisfied the ductility limitation requirement in reference to FEMA-350, revealing a potential to the application in seismic steel structures.

Behaviour and design of prefabricated CFST stub columns with PCC connections under compression

This paper investigates the compressive behaviour of prefabricated concrete-filled steel tube (CFST) columns with prefabricated column–column (PCC) connections. The innovative PCC connections are designed using conventional structural bolts instead of expensive blind bolts to connect two prefabricated CFST columns, simplifying the construction process and rendering the construction cost-effective. The compressive behaviour of prefabricated CFST columns with or without PCC connections has been investigated numerically. Parametric studies have been conducted to investigate the effect of different parameters of PCC connections, including connection configurations, horizontal and vertical stiffeners of connections, diameter of the coupling bolt, steel tube thickness, yield strength of steel tube, and compression strength of concrete, on the compressive behaviour of CFST columns with PCC connections. The prefabricated CSFT columns with the developed PCC connections are able to achieve similar compressive strengths that are achieved by the CFST columns without connections. Therefore, the developed PCC connections can be used to construct prefabricated CFST columns for the prefabricated steel–concrete composite structures.

Use of Fine-Grained Heat-Strengthened Steels to Increase the Operation Qualities of Bunker Capacities from Thin-Walled Galvanized Profiles

Purpose. The work is aimed to study the use efficiency of fine-grained heat-strengthened steels (mainly 10G2FB) for steel bunker capacities. At the same time, the structural scheme of such a structure using corrugated steel sheets is considered as the main variant. Methodology. To achieve this purpose, a series of numerical calculations was carried out for a steel bunker capacity of a pyramidal-prismatic type with overall dimensions in plan view of 6×5.2 m and a total height of 4.5 m. The capacity was designed for complicated working conditions, in particular, increased loads, including long-term dynamic ones. The potential possibility of operating the container under conditions of high or low temperatures was also taken into account. At the same time, both the traditional structural scheme of a bunker capacity with horizontal stiffening ribs and the developed structural scheme based on corrugated steel sheets were analyzed. The calculations were carried out by the finite element method based on the SCAD for Windows project complex. Findings. Based on the results of the analysis and comparison of the data obtained in numerical calculations, it was found that the use of fine-grained heat-strengthened high-strength steels (for example, steel 10G2FB) for bunker capacities, both the traditional structural scheme with stiffening ribs and the developed structural scheme based on corrugated sheets, allows reducing material consumption by about 30% in both cases. At the same time, due to the good performance of fine-grained heat-strengthened steel 10G2FB, both at high and at low temperatures, it can be effectively used for steel bunker capacities that work in difficult conditions. Originality. The possibility and efficiency of the use of fine-grained, heat-strengthened high-strength steels for the construction of a steel bunker capacity is estimated. At the same time, such an estimation was given not only for structures of the traditional structural scheme with horizontal stiffening ribs, but also for bunkers with a developed structural scheme based on corrugated sheets. Practical value. From a practical point of view, quantitative parameters of the stress-strain state were obtained during investigations of various design variants for a steel bunker capacity. The data are presented in a compact form that is easy to evaluate and compare. They allow us to state about the improvement of the operation characteristics of capacities and the potential reduction of the risks of their failures and accidents during operation.

Analytical study on the effect of horizontal stiffeners on the ultimate capacity of steel box girder bridges

Analytical study on the effect of horizontal stiffeners on the ultimate capacity of steel box girder bridges

Shear strength of stiffened steel shear walls with considering the gravity load effect through a three-segment distribution

Former investigations have shown that the gravity load will significantly reduce the shear strength of the steel shear walls (SSW), especially in the case of a stocky wall that has high buckling stress under heavy compression load. However, only a few have been carried out on stiffened SSW, even though it has high compression buckling stress. The present study aims to narrow the knowledge gap by conducting a theoretical analysis and a numerical evaluation. The stiffened SSW is divided into several sub-walls by vertical and horizontal stiffeners. For each sub-wall, a three-segment vertical stress distribution under the gravity load is proposed. The tension field stress of inclination tension strips of each sub-wall, with considering the effect of the gravity load through the proposed three-segment vertical stress distribution, is determined through the Von Mises yield criterion. Shear strength of the wall is calculated as the sum of the shear strength of each sub-wall, while that of the boundary frame is determined according to a wall-frame model. To evaluate the proposed approach, an experimentally verified finite element model using the software ANSYS/LS-DYNA is developed. The results show that the proposed approach is able to accurately consider the gravity load effect of the stiffened SSWs of different stiffeners configurations.

Shear behavior of stiffened single perforated lean duplex stainless steel (LDSS) rectangular hollow beams

This paper presents the study on shear behavior of stiffened single perforated LDSS rectangular hollow beam, considering various orientations / patterns viz., inclined (IS), vertical (VS), horizontal (HS) and ring (RS); and effect of various cross-sections i.e. flat, angular and semi-circular (considering same material consumption). Based on the study, it has been found that in general, inclined stiffener (with flat cross-section) is relatively most effective in enhancing the shear capacity of perforated beams. For the inclined stiffeners, it is observed that the rate of increase in shear capacity (Vu/Vy) increases (in a non linear trend) with increasing stiffener length for higher stiffener thicknesses. In the case of vertical and horizontal stiffeners, there appears to have no/little significant improvement in shear capacity for both the variation in length, width and thickness. For the ring stiffeners, it is found that, shear capacity increases with increase in both breadth and thickness of the stiffeners. Comparison made between angular and semi-circular sections (keeping the same cross sectional area) showed that both the sections predicted similar behavior of shear capacity.

Experimental verification of seismic performance of built-up beam-to-column connections with ductile detail

The sections of hot-rolled H-beams produced by steel manufacturers in South Korea do not fully meet the requirements of recent buildings. Although custom-made built-up H-beams meet field requirements, they require a highly reliable manufacturing process through batch production and quality control. To this end, a steel manufacturer in South Korea recently constructed a production line for manufacturing built-up H-beams with uniform quality, and has attempted to address the problems of inefficient sections of hot-rolled members and the lack of large sections with a beam depth of 900 mm or greater. Furthermore, the steel manufacturer has attempted to produce highly ductile connection details that can be applied to large H-beam sections with a maximum depth exceeding that of existing hot-rolled H-beams to ensure seismic performance. In this study, real-scale structural performance tests were conducted on the beam-to-column connections of large built-up H-beams with ductile connection details suitable for site conditions. Built-up H-beams with a beam depth of 1000 mm were selected as specimens. The authors used a beam-end seismic welding detail and horizontal stiffener reinforcement detail, which were verified in a previous experimental study on beams with conventional depths. The test results were described in accordance with the connection performance verification process presented in the AISC standard and the seismic design code adopted in South Korea. The structural stability of the applied connection details was analyzed.