Stiffening Ribs Research Articles

Seismic performance of square concrete-filled steel tubular column-composite beam single-side bolted joints: An experimental and numerical study

The seismic behavior of square concrete-filled steel tubular (SCFST) column-composite beam single-side bolted joints has not been fully investigated. To address this gap, both experimental and numerical studies were conducted, focusing on the impact of various parameters. This research entailed constructing and testing nine prototypes of SCFST column-composite beam single-side bolted joints, scaled to a 1/2 zoom ratio, under conditions simulating seismic loads. Variables considered in these tests included the presence of stiffener ribs, bidirectional stirrups, the section height of the steel beam, and the axial compression ratio. A finite element model was developed and its accuracy was affirmed through comparison with the experimental outcomes. The analysis encompassed several aspects: the hysteretic response, skeleton curves, strain, ductility, stiffness degradation, and energy dissipation. The findings revealed that the design of bidirectional stirrups is crucial, especially under high axial compression ratios (n = 0.8), in preventing compression-flexure failures at the column ends. The hysteresis curves of the specimens manifested in two distinct shapes: spindle-shaped with bidirectional stirrups and bow-shaped without them. Enhancements such as the addition of stiffener ribs or an increase in the steel beam’s height resulted in a more comprehensive hysteresis curve, and improvements in the initial rotational stiffness, flexural bearing capacity, and energy dissipation capability of the specimens were observed. Notably, even when the beam-column bending capacity ratio in the SCFST column-composite beam single-side bolted joint reached 1.5, the joint’s energy absorption was predominantly governed by the beam’s energy dissipation.

Effect of process parameters on the mechanical performance of fusion-joined additively manufactured segments

PurposeHerein, the authors report the effects of printing parameters, joining method, and annealing conditions on the structural performance of fusion-joined short-beam sections produced by additive manufacturing.Design/methodology/approachThe authors first identified appropriate printing parameters for joining segmented short beams and then used those parameters to print and fusion-join segments with different configurations of stiffeners to form a longer section of a wing or small wind turbine blade structure.FindingsIt was found that the beams with three lateral and three base stiffening ribs give the highest flexural strength among the three beams investigated. Results on joined beams annealed at different conditions showed that annealing at 70 °C for 0.5 h yields higher performance than annealing at the same temperature for longer times. It is also found that in the case of the hot-plate-welded three-dimensional (3D)-printed structures, no annealing is needed for reaching a high strength-to-weight ratio, but annealing is helpful for maximizing the modulus-to-weight ratio. Both thermal buckling and edge wrapping were observed under annealing at 70°C for 0.5 h for 3D-printed beams comprising two lateral and four base stiffening plates.Originality/valueFusion-joining of additively manufactured segments is needed owing to the constraint in building volume of a typical commercial 3D-printer. However, study of the effect of process parameters is needed to quantify their effect on mechanical performance. This investigation has therefore identified key printing parameters and annealing conditions for fusion-joining short segments to form larger structures, from multiple 3D-printed sections, such as wind blade structures.

Numerical analysis of soil–steel composite structure performance at ultimate load: impact of stiffening ribs and geotextile reinforcement

This study investigates soil–steel composite structures, emphasizing the role of stiffening ribs and geotextile reinforcement through comprehensive numerical modeling. This study presents a two-dimensional finite element analysis (FEA) and compares the influence of stiffening rib and geotextile on the ultimate bearing capacity of the soil–steel composite structures. The results of this study demonstrate a significant enhancement in load capacity. Specifically, a notable 47% improvement was observed with a stiffening rib, and a 26% increase was noted with the use of a single layer of geotextile. Under peak load, the vertical displacement at the crown exceeds the permissible standard for all models except for one model, while bending moments reach their limits, marking a failure mode of composite system considered. Structures with stiffened ribs reach their load capacity due to the creation of a plastic hinge around the shoulder and haunch of the shell. On the other hand, in structures without stiffening ribs, the crown and haunch section of the shell becomes fully plastic under peak load. The maximum axial thrust is shown in geotextile-reinforced structure, reaching 78% of the shell maximum capacity due to compression. Eventually, stiffening rib substantially improves overall load-bearing capacity of the soil–steel composite structures, and geotextile placement in the upper part of the backfill reduces shell deflection due to bending.

An extension of composite bending strain κMITC3+ scheme in analysis of shell structures reinforced with rib stiffeners

In this paper, the composite bending strain κMITC3+ approach is extended for analyzing the shell structural domain in the rib-stiffened shell problems. Developed to achieve enhanced performance and emphasize a softer bending behavior, this novel element employs a polynomial projection technique to construct an assumed composite bending strain field. This technique originates from the Hu-Washizu three-filed principle and the orthogonality condition. In the membrane component context, an improved Allman-like triangular element is utilized to remove the spurious energy mode commonly associated with classical Allman's theory. To address the shear-locking phenomenon within Timoshenko's beam model for the rib stiffeners, a selective/reduced integration approach is adopted. This involves using a standard two-point Gaussian rule for accurate bending strain computation and a one-point Gaussian rule for shear strain computation. The numerical examples showcased in our study unequivocally highlight the distinct superiority of the κMITC3+ element.

Study of Pullout Tests on Plastic Geogrids with Vertical Stiffener Ribs of Aluminum Angles

Study of Pullout Tests on Plastic Geogrids with Vertical Stiffener Ribs of Aluminum Angles

Finite Element Analysis on the Seismic Performance of Concrete-Filled Steel Tube Columns with a Multiple-Chamber Round-Ended Cross-Section

This study proposes a form of concrete-filled steel tube column with a multiple-chamber round-ended cross-section (M-CFST). Longitudinal and transverse stiffening ribs divide the circular-ended section into different chambers, strengthening the steel tube’s confinement effect on the core concrete and improving the component’s seismic performance. A three-dimensional finite element (FE) solid model of the M-CFST is created by employing the FE software ABAQUS. Quasi-static analysis is conducted to investigate the influence of parameters, such as chamber arrangement, aspect ratio, and axial compression ratio, on flexural hysteresis performance. Moreover, the failure modes, hysteresis curves, skeleton curves, strain development, and energy dissipation of the components are analyzed. The results show the following: (1) The FE model presented in this study can simulate the quasi-static behavior of CFST columns accurately, and the calculated results are in good agreement with the measured values. (2) The seismic performance of the composite column is excellent, with a large number of chambers leading to a robust hysteresis curve for the composite columns, resulting in increased bearing capacity and energy dissipation capacity. However, the energy dissipation performance of the specimen with a two-chamber arrangement is slightly lower than that with a single-chamber arrangement. (3) The results of the finite element analysis suggest that the long and short sides of the CFST columns with a large length–width ratio should be arranged to be relatively close in length.

Experimental Investigation of Load-Bearing Capacity in EN AW-2024-T3 Aluminum Alloy Sheets Strengthened by SPIF-Fabricated Stiffening Rib.

The aluminum strength-to-weight ratio has become a highly significant factor in industrial applications. Placing stiffening ribs along the surface can significantly improve the panel's resistance to bending and compression in aluminum alloys. This study used single-point incremental forming (SPIF) to fabricate stiffening ribs for 1 mm and 3 mm thick aluminum alloy EN AW-2024-T3 sheets. A universal compression machine was used to investigate sheet deformation. The resulting deformation was examined using non-contact digital image correlation (DIC) based on several high-resolution cameras. The results showed that deformation progressively escalated from the edges toward the center, and the highest buckling values were confined within the non-strengthened area. Specimens with a larger thickness (3 mm) showed better effectiveness against buckling and bending for each applied load: 8 kN or 10 kN. Additionally, the displacement from the sheet surface decreased by 60% for sheets 3 mm thick and by half for sheets 1 mm thick, which indicated that thicker sheets could resist deformation better.

Design Method for Local Buckling Resistance of Double Steel Plate–Concrete Composite Walls with Stiffening Ribs and Tie Plates

An ordinary double steel plate–concrete composite wall (ODSC wall) is composed of core concrete, the faceplates, and shear connectors such as studs, etc. Based on an ODSC wall, a new type of stiffened double steel plate–concrete composite wall (SDSC wall) is conceived by incorporating additional stiffeners and tie plates on the internal surface, which aims to improve the local stability of the faceplates. In the authors’ previous study, a series of axial compression tests were conducted on the SDSC walls. The SDSC walls in the test showed better mechanical performance, as the presence of stiffeners changed the buckling deformation mode and significantly improved the corresponding local buckling stress and ultimate strength. In this paper, a comprehensive summary of the prior research on SDSC walls is provided, and the effect of the constructive parameters on the local stability is discussed. The results reveal that the modified formula of the critical stress can degrade to the Euler formula when the stiffener-to-stud spacing ratio (i.e., a/B ratio) approaches infinity. What is more, the analysis model is also applicable for DSC walls with enclosed side plates, and the proposed formula can predict the buckling stress of the SDSC walls with different a/B ratios. In addition, according to the analysis of the numerical simulation, a design approach for SDSC walls to prevent local buckling is provided, which is applicable in practical engineering applications.

A metamaterial-assisted coda wave interferometry method with nonlinear guided waves for local incipient damage monitoring in complex structures

Nonlinear guided waves exhibit high sensitivity to material microstructural changes, thus attracting increasing attention for incipient damage monitoring applications. However, conventional nonlinear guided-wave-based methods suffer from two major deficiencies which hinder their applications: (1) mostly relying on the first arrivals of wave signals, they apply to limited inspection areas in simple structures in order to avoid wave reflections from structural discontinuities or boundaries; (2) they are prone to numerous deceptive nonlinear sources in the measurement system which might overwhelm damage-induced signal components. To tackle these challenges, we propose a metamaterial-assisted coda wave interferometry (CWI) method using second harmonic Lamb waves, applicable to the monitoring of local incipient damage in complex structures. Embracing the metamaterial concept, a so-called meta-screen is designed, whose geometry and layout can be flexibly tailored to target specific inspection zones in a structure. Capitalizing on its customized bandgap features, the proposed meta-screen allows for the passing of fundamental waves while preventing the second harmonic components generated by deceptive nonlinear sources from penetrating into the inspection area. Through numerical analyses on a plate with a rib stiffener, the efficacy of the meta-screen and the influence of occasional disturbance and regular pollution are evaluated. Experimental validations on an adhesive structure also confirm the superior sensitivity of the nonlinear coda waves to incipient damage, which is further enhanced by the deployment of the meta-screen alongside improved robustness against deceptive nonlinear sources outside the inspection area. The proposed metamaterial-assisted CWI method with second harmonic Lamb waves holds great promise for local incipient damage monitoring of complex structures.

Study on mechanical properties of wind turbine tower reinforced by ribbed interlayer

In order to avoid the economic loss caused by the demolition and reconstruction of old steel wind turbine towers and to meet the demand of new generating units for tower strength and stiffness, this paper proposes a laminated ribbed structure for strengthening old wind turbine towers based on the concept of hollow laminated steel pipe concrete. The four interlayer ribbed reinforced cylinder specimens were made of two steel cylinders, both round and concentric, with vertical stiffening ribs evenly arranged on the inner surface of the outer cylinder and the outer surface of the inner cylinder, and concrete was poured between the two cylinders. The number of cavities, concrete thickness and shear-to-span ratio were used as the test parameters to conduct compression-bending tests on five specimens. The test results show that: the damage phenomenon of the specimen is obvious, the material performance of each component is fully played, and the stiffening ribs can effectively alleviate the local bulging of the specimen; in terms of ultimate bearing capacity, the most influential is the shear-to-span ratio, the smaller the shear-to-span ratio, the larger the ultimate bearing capacity, increasing the concrete thickness and the number of cavities can effectively improve the ultimate bearing capacity; in terms of initial stiffness and ductility, the increase of the number of cavities will significantly improve the initial stiffness and ductility of the specimen. In terms of initial stiffness and ductility, increasing the number of cavities will significantly improve the initial stiffness and ductility of the specimen. The reinforcement effect of sandwich layer with ribbed structure on the tower structure is remarkable. The finite element analysis software ABAQUS was used to establish a model consistent with the test, and the calculation results were compared with the test results to verify the feasibility and accuracy of the established model and the material intrinsic structure relationship. On this basis, typical members are selected, and the stresses and plastic strains are combined with the longitudinal stresses and plastic strains to analyze the whole process of the stresses in the reinforced barrel of the sandwich ribbed structure in depth. The research results provide the theoretical basis and experimental basis for wind turbine tower reinforcement.

Deformation and energy dissipation of steel box girders of cable-stayed bridges subjected to blast loadings

Steel box girders are widely used in cable-stayed bridges, while they are prone to severe damage under explosions. This paper investigates the deformation and energy dissipation of steel box girder of cable-stayed bridges under blast impact, caused by the accidental explosions of tanker trucks and vehicles. In this study, Hypermesh and LS-DYNA are employed to simulate the dynamic responses of a real steel box girder cable-stayed bridge under explosions. The deformation response and energy absorption of the box girder under explosions are investigated. Several failure modes and failure processes are analyzed and summarized. The findings indicate that the failure mode of an orthotropic steel bridge panel under blast impact is primarily local damage, with the damage process being divided into three stages: local plate deformation, fragment formation, and petal formation. For bridge deck explosions, the main energy dissipation components of steel girders are the bridge panel, web, diaphragm and rib stiffeners. The research results can provide the basis for the follow-up study on the anti-explosion safety of bridge structures.

Numerical investigation on seismic performance of reinforced rib-double steel plate concrete combination shear wall

Double steel plate concrete composite shear wall (SCSW) has been widely utilized in nuclear power plants and high-rise structures, and its shear connectors have a substantial impact on the seismic performance of SCSW. Therefore, in this study, the mechanical properties of SCSW with angle stiffening ribs as shear connections were parametrically examined for the reactor containment structure of nuclear power plants. The axial compression ratio of the SCSW, the spacing of the angle stiffening rib arrangement and the thickness of the angle stiffening rib steel plate were selected as the study parameters. Four finite element models were constructed by using the finite element program named ABAQUS to verify the experimental results of our team, and 13 finite element models were established to investigate the selected three parameters. Thus, the shear capacity, deformation capacity, ductility and energy dissipation capacity of SCSW were determined. The research results show that: compared with studs, using stiffened ribs as shear connectors can significantly enhance the mechanical properties of SCSW; When the axial compression ratio is 0.3–0.4, the seismic performance of SCSW can be maximized; with the lowering of stiffener gap, the shear bearing capacity is greatly enhanced, and when the gap is lowered to a specific distance, the shear bearing capacity has no major affect; in addition, increasing the thickness of stiffeners can significantly increase the shear capacity, ductility and energy dissipation capacity of SCSW. With the rise in the thickness of angle stiffening ribs, the improvement rate of each mechanical property index slows down. Finally, the shear bearing capacity calculation formula of SCSW with angle stiffening ribs as shear connectors is derived. The average error between the theoretical calculation formula and the finite element calculation results is 8% demonstrating that the theoretical formula is reliable. This study can provide reference for the design of SCSW.

Investigation of the Bearing Capacity of Transport Constructions Made of Corrugated Metal Structures Reinforced with Transversal Stiffening Ribs

Methods of increasing the bearing capacity of corrugated metal structures of transport constructions using transversal stiffening ribs in the form of additional corrugation and stiffeners are given. Based on the theory of elasticity, a mathematical model for estimating the stress-strain state of transport constructions made of corrugated metal structures reinforced with stiffening ribs in the form of double corrugation was developed. The method of determining equivalent forces during rolling stock passage is offered. It has been established that double corrugation increases the bearing capacity of corrugated metal structures. Therefore, additional corrugation of corrugated metal structures reduces stresses by up to 20% and deflections by 50%. The obtained results show that the increase in rolling stock speed does not lead to a significant increase in stresses and strains in CMS when the railway track corresponds to the design state.

STRENGTH AND DUCTILITY EVALUATION OF THIN-WALLED STEEL TUBULAR BRIDGE PIERS UNDER CYCLIC LOADING

Numerical simulations are being conducted on the behavior of thin-walled steel tubular bridge piers under cyclic lateral loading in the presence of constant axial compression loads. The effects of cyclic lateral loading on the behavior of the thin-walled steel tubular bridge piers have been evaluated through analysis of the hysteresis curve, envelope curve, stiffness, and strength degradation characteristics, and energy-dissipating capacity, including interaction effects of local buckling and flexural buckling, and post-buckling regimes. This study also compares the numerical analysis with experimental results available in the literature to validate the accuracy of the proposed finite element model. Based on this model, a range of relevant material and structural parameters will be investigated in future work. Numerous numerical specimens will be designed and analyzed, gaining further information about the influence of width-to-thickness ratio, Rt, column slenderness ratio, , material properties of the embedded shell plate, spacing of transverse stiffening ribs of the shell, height, and properties of partially infill concrete, and axial compression load.

Structural Stability of Tailwater Penstock in Xiamen Pumped Storage Power Station

To study the external water pressure that can be borne by the steel lining of the tailwater penstock of a pumped storage power station, the optimization of the steel lining shape provides the basis for ensuring its normal operation. In this paper, based on the finite element method and finite element analysis software ABAQUS, the calculation and analysis model of different stiffening ring schemes for tailrace penstock is established, structural stability is calculated and the influence of different stiffening schemes is compared and analyzed. The results show that the structural stability can meet the requirements of the code by setting the T-shaped stiffening ring and longitudinal stiffening rib. With the addition of longitudinal stiffeners, the steel lining tends to the stress characteristics of the two-way slab, and the overall stress deformation tends to be balanced, which can improve the external pressure resistance of the steel lining in the gradual change section to a certain extent.

Influence of polymer aggregate reinforcement on the dynamics of three-layer cylindrical structure of elliptical cross-section

The dynamic behavior of a three-layer cylindrical structure of normal elliptical cross-section with a discrete polymer filler under internal non-stationary loading was investigated. A finite element model of the structure was created and calculations of normal deflections and normal stresses of its bearing layers were performed using a software and calculation complex Fimap with NX Nastran. The values of deflections and stresses of the specified layers in the absence and presence of reinforcement of the polymer aggregate structure at the ratio of elasticity of the material of bearing layers and aggregate are given E1,2/Et=500.
 Reinforcement of polymer aggregate with metal stiffening ribs significantly affects the dynamic behavior of the three-layer cylindrical structure. The presence of this factor synchronized the stress-strain layer of the bearing layers of the structure, reduced the values of normal deflections and stresses of the bearing layers of the cylindrical three-layer structure. The effectiveness of reinforcement of polymer aggregate is confirmed by other materials, which indicates the feasibility of the practical use of such a constructive measure.

Robot-assisted conformal additive manufacturing for continuous fibre-reinforced grid-stiffened shell structures

ABSTRACT The advents in continuous fibre-reinforced polymer additive manufacturing (CFRP-AM) present unprecedented opportunities for the rapid development of next-generation high-performance composites with selectively and spatially distributed reinforcement. However, the widely adopted 3-degree-of-freedom motion configuration in current CFRP-AM systems hinders the exploration of composite structures with non-planar fibre layouts. This work presents a novel conformal CFRP-AM system to fabricate grid-stiffened shell structures leveraging its multi-DoF motion to pattern spatial features. The system integrates a 6-axis robot with an optimally designed co-extrusion module and operates through a design-to-manufacturing workflow. The proposed workflow includes three steps: system calibration, conformal toolpath generation, and process implementation. The conformal toolpath generation is a surface-mapping-based method that allows a simultaneous exploration of various geometric designs and their toolpaths. Experimental comparisons were made between parts fabricated by different processes, i.e., planar and conformal based, with different toolpaths, i.e., shells filled with zigzag and arc-offset patterns, and with various geometric designs, i.e., stiffener ribs with different crossline angles. The results manifest that the proposed system can significantly improve the compression strength and stiffness of grid-stiffened shell structures. Meanwhile, the additional design freedom on process and structure opens up a new possibility to customise their mechanical performance.

Response of Seismically Damaged Steel Reduced Beam Section Joints under Fire

The behaviour of seismically damaged steel joints with reduced beam section (RBS) at elevated temperatures has not been widely investigated yet. Therefore, the study summarized in this article aimed to (i) analyse the response of RBS joints at high temperatures and (ii) investigate the influence of plastic damage, due to cyclic loading, on the fire performance of the joints. A set of RBS joints with rib stiffeners on the both lower and upper beam flanges was designed according to European standards and the following parameters were considered: (i) location of the joint (i.e., internal or external joint) and (ii) reduction in the beam flexural resistance (i.e., 65% or 80% of the beam plastic moment). The mechanical response of these joints was simulated by means of finite element models (FEM). The accuracy and effectiveness of the adopted modelling assumptions to mimic the seismic response of the joints were validated against experimental results available from the existing literature. The numerical results highlight that under cyclic loading, all investigated joints exhibit ductile behaviour, allowing the concentration of the plastic deformation within the reduced segment of the beam. The designed reduction in the beam flexural resistance influences the joint fire performance, being impaired in the cases with lower flexural resistance. In contrast, the imposed cyclic pre-damage does not appreciably affect the fire resistance of the investigated joints.

Revisiting the Fibonacci spiral pattern for stiffening rib design

For a long period, phyllotaxis (the arrangement of leaves on a plant stem) has been observed as an interesting morphological property of various plants, and the phyllotactic spirals form a distinctive class of patterns in nature. These days, the unique patterns governed by the Fibonacci sequence, or the golden ratio in a deeper sense, have moved beyond the botanical system and came to be universal, occurring in architectural and structural design. In this work, we develop a design approach for curvilinear stiffening ribs which follow the Fibonacci spiral pattern. The parametric model of the designed ribs is built according to two parameters, one discrete and another continuous. Parametric studies on the two variables are performed to assess the potential mechanical advantages of the Fibonacci spiral pattern in stiffening structures. The deformation-, vibration- and buckling-resisting capacities are investigated for thin-walled stiffening plates with a central cutout. Moreover, an attempt is devoted to clarifying the rationality of curvilinear stiffening ribs’ employment in other designs. Lastly, we demonstrate that the developed protocol does not limit itself to planar structures with cutouts, and it is easy to be extended to stiffening ribs on curved surfaces, where the gain in mechanical property is observed to be even more visible and pronounced.

Universal reposition and fixation ring for surgical treatment of acetabulum fractures: preliminary results of laboratory static tests

BACKGROUND: Several structures are widely used in the surgical treatment of long-standing fractures of the BB, such as support rings of M. Muller, BurchSchneider, rings of PROTEK (Switzerland) implanted in the BB. In traumatology practice, rings are used to strengthen fractured walls. However, these rings are not functionally designed for open reposition and fixation of columns and fractures, followed by TBS endoprosthetics with cement fixation of the components of the endoprosthesis. Recently, primary endoprosthetics of EP TBS became the trend for displaced fractures of the BB, which is considered the best option for surgical treatment of BB fractures. In the literature, no analogs of our ring were available, which provides CHP in the treatment of BB fractures.
 AIM: To study the deformation properties of a repositional fixation ring with an outer diameter of 52 mm with a stiffening rib.
 MATERIALS AND METHODS: A ring has been developed for the surgical treatment of acetabulum fractures (Patent for Invention No. 2692526 dated 26.06.2019 under Application No. 2018133671 dated 25.09.2018.; Bul. No. 18 dated 26.06.2019). For mechanical testing, a ring with an outer diameter of 52 mm with a stiffening rib was manufactured by sequential sintering using additive technologies by Konmet LLC (Moscow). Laboratory mechanical tests were conducted by the Testing Laboratory of Medical Devices and Materials of the FSBI NMIC TO named after N.N. Priorov (Moscow).
 RESULTS: A static testing of a ring with a stiffener for compression, stretching, torsion, joint stretching, and twisting of the edges of the ring connector was performed, and its deformation properties and reaction to external loads during static tests were examined. The load corresponded to the deformation of 2 mm, kN; compression, 0.209; tension, 0.082; torsion (angle of rotation of 5 degrees, Nm), 9.422; and joint stretching with twisting of the edges of the ring connector (load corresponding to the deformation of 10 mm, kN), 0.060.
 CONCLUSION: The results of the initial study of the deformation behaviors of the new ring design clearly show the elastic nature and deformation properties of the ring, which were attributed to the stiffening rib. The positive primary results of studying the deformation behaviors of the ring reinforced with a stiffening rib indicate the possibility for clinical trials and the direction of further refinement of the design..