Types Of Stiffeners Research Articles

Effect of vertical stiffeners on the seismic performance of T‐shaped CFST column to steel beam joint

SummarySpecial‐shaped concrete‐filled steel tubular (SCFST) columns have recently been developed for efficient steel‐concrete composite construction. In this study, a novel vertical stiffener joint for the SCFST column and steel beam frame structure is proposed. Five SCFST columns with H‐section beam joints were investigated under cycling loading. The test parameters mainly consider the column stiffening form, vertical stiffener type, and the column axial load. The failure pattern, hysteretic curves, and strain development of specimens are analyzed. Experimental results demonstrate the proposed joint with vertical stiffeners can develop the steel beam's full plastic flexural capacity and exhibit favorable seismic performance. In addition, a finite element (FE) model is developed to explore the effects of the following parameters on the hysteretic performance: vertical stiffener sizes, width‐to‐thickness ratio of column steel tube, and the column axial load. Based on the experimental and FE analyses, a stress and deformation model of the joint steel tube was established. To facilitate the practical applications, a calculation formula for joint strength was also put forward, considering the contribution of vertical stiffener, and front and side steel plates of the joint steel tube.

Low Velocity Impact Behavior of Curved Composite Panels Reinforced with Different Types of Stiffeners Used in Air Vehicle

This study aims to investigate the low-velocity impact behavior of curved composite plates commonly employed in aviation fuselage and wing surfaces using numerical methods. Layered plates fabricated from E-Glass Epoxy were reinforced with various types of stiffeners and subjected to impacts whit a 12 mm diameter impactor at a velocity of 2.5 m/s. The time-dependent variation of force and displacement on the stiffened curved plates resulting from the impact was analyzed. Furthermore, the temporal variation in the amount of energy absorbed by the plate was observed. The results indicate that plates reinforced with I, T, and blade-type stiffeners absorbed 35.78%, 38.11%, and 37.78% of the impact energy, respectively. Among these, plates with T-type reinforcements exhibited the least post-impact deformation. Particularly noteworthy is the permanent deformation of 3.7 mm experienced by the plate reinforced with blade-type stiffeners.

A review on buckling of the laminated composite panel under in-plane load

Abstract The review paper deals with a literature review on buckling analysis by different methods of laminated plates with different types of stiffeners which has been conducted in recent years. Analytical studies, experimental studies, finite element analysis, and other computational methods have been implemented by researchers on the stiffened panels under compression and shear for determination of the buckling behavior of the panel with I-type, blade-type, T-type, and hat-stiffeners. Some literature has been found on the panel with the influence of variation of the stiffener depth for the determination of buckling capacity. Very few literatures, non-linear finite element (FE) have been implemented for the determination of the effect of debonding damage between plate-stiffener of the panel but have not been reported parametric data about the effect of cohesive parameters of plate-stiffener and delamination of plies of the composites stiffened panel for post-buckling analysis. This paper also provides a literature survey based on the buckling performance of the plates with the application of different shapes of stiffeners.

Flexural Behavior of Pultruded GFRP–Concrete Composite Beams Strengthened with GFRP Stiffeners

The utilization and incorporation of glass fiber-reinforced plastics (GFRP) in structural applications and architectural constructions are progressively gaining prominence. Therefore, this paper experimentally and numerically investigates the use of GFRP I-beams in conjunction with concrete slabs to form composite beams. The experimental design incorporated 2600 mm long GFRP I-beams which were connected compositely to concrete slabs with a 500 mm width and 80 mm thickness. The concrete slabs are categorized into two groups: concrete slabs cast using normal-strength concrete (NSC), and concrete slabs prepared using high-strength concrete (HSC). Various parameters like the type of concrete (normal and high-strength concrete), type of stiffeners bonded to the composite section (bolt–epoxy or bolt only), and inclusion of corrugated metal sheets were investigated. To obtain the full shear connection between the GFRP I-sections and concrete slabs, two rows of shear connectors in the form of bolts were utilized. These shear connectors were erected to the top flange of the GFRP I-sections to compositely connect between the GFRP I-beams and the concrete slabs as well as the corrugated metal sheets. The strengthening of the shear webs of GFRP I-beams with GFRP T-section stiffeners resulted in an enhancement in the flexural and shear strength. The failure loads in the case of the bolt–epoxy connection for the stiffeners were 8.2% and 10.0% higher than those in the case of bolt only when the concrete compressive strengths were 20.1 MPa and 52.3 MPa, respectively. Moreover, the effect of the concrete compressive strength was vital where the failure loads increased by 79.9% and 77.1% when HSC was used instead of NSC for the cases of bolt–epoxy and bolt only, respectively. The epoxy adhesive used in conjunction with mechanical connectors, specifically bolts, resulted in sufficient composite action and delayed shear failure within the web of the GFRP beam. For the specimens with bolt–epoxy connection, strain levels in the concrete slabs were consistently higher than in the other specimens with bolts alone at the same loading level. The concrete slabs integrated with HSC registered strain levels that were 20.0% and 21.8% greater for bolt–epoxy and bolt-only connections, respectively, when compared to those using normal-strength concrete (NSC). This discrepancy can likely be credited to the enhanced composite interaction between the concrete slabs and the GFRP I-beams. In addition, ABAQUS software (version 6.2) was used to develop FE models to analyze the tested composite beams and provide a parametric study using the verified models.

The cyclic performance of column base plate connections using different types of stiffeners

Column base connections represent the support system of a structure, and they should be strong enough to sustain the transmitted demands between the columns and foundation. This study describes numerically the performance of strengthened column base plate connections under cyclic loading. Four types of stiffeners were considered in the analysis: bracket plates, angles, channels with vertical stiffeners, and built-up stiffeners. The efficiency of used stiffeners, the cyclic performance of the strengthened connections, and along with the failure modes were investigated. The numerical results showed that all the proposed strengthening methods have sufficient flexural strength and stiffness higher than the column. A pinched hysteretic response was observed for all strengthened connections under the applied cyclic loading. The built-up stiffener presented the maximum moment capacity and rotational stiffness among the other configurations. Using strengthened connections with more stiffeners made the anchor rods the fuse elements in the connection.

On the Optimal Shape and Placement of Longitudinal Stiffeners in Longitudinally Stiffened Plates

AbstractLongitudinal stiffeners are widely used in plated structures to prevent buckling of the slender plate elements and, therefore, to increase the load bearing capacity of these structures. There has been extensive research in the past regarding the shapes, sizes, and placement of these longitudinal stiffeners, however, there has been little research to make comparison between the different stiffener shapes across different numbers of stiffeners. The presented study compares the use of a single open stiffener, single closed stiffener, as well as the use of two open stiffeners. A numerical parametric study was conducted, considering different stiffener types, rigidities, and aspect ratios of the plates, for the cases of pure bending and compressions. The results of the study confirm that using a single closed stiffener or two open stiffeners is almost always more advantageous than the use of a single open stiffener. Furthermore, the study highlighted that it might be more advantageous to use two open stiffeners instead a single closed one.

Mechanical Behaviour of the Rotating Target SORGENTINA-RF

The SORGENTINA-RF project aims at developing a 14 MeV neutron source based on a deuterium/tritium ion accelerator and a rotating target where fusion reactions take place. Among the different research fields, the most interesting and promising is medical radioisotope production. In this framework, intense research work on the design of the rotating target has been carried out. More in detail, to define the optimal design configuration, a sensitivity analysis on the mechanical performance of the rotating target considering the influence of some relevant parameters, such as material type, thickness, and presence of internal stiffeners, was carried out. Among the materials analyzed, aluminium alloy represents the best compromise to efficiently address all the critical requirements in the design phase. One of the most demanding project requirements that the conceptual design must fulfill is the ability of the target to dissipate a thermal power of 250 kW without precluding its mechanical properties and resistance. To investigate the performance of the rotating target, some thermo-mechanical analyses were undertaken with finite element method under some thermal transients and mechanical loads able to simulate the working conditions of the system. The numerical results emphasise the target’s ability to withstand operating conditions. The main outcomes of the present study have been implemented as engineering solutions in the project design.

Progressive collapse analysis and ultimate strength estimation of continuous stiffened panel under longitudinal extreme cyclic load and lateral pressure

Stiffened panel is a fundamental member of hull structures which is designed to withstand multiple loads such as revered cyclic load and lateral pressure. At present the ultimate strength of stiffened panel is conventionally determined by the monotonic compression criterion, ignoring the real progressive collapse of ship in rough sea conditions. To provide useful insights for improving the ship design, the present study focuses on dealing with the structural collapse characteristics and ultimate strength estimation of continuous stiffened panel under combined longitudinal extreme cyclic load and lateral pressure. A large number of nonlinear finite element analyses (FEA) are conducted to identify the influences of various factors on the failure mode and ultimate strength including the slenderness ratio of local panel, stiffener type, size and number, sequence and amplitude of the cyclic load, cycle number and lateral pressure. It is found that the ultimate limit state behaviours are governed by the coupling effects of several influential parameters. Based on artificial neural networks (ANN), a prediction model with high accuracy is proposed to evaluate the ultimate strength in different cycles.

Applications of bond-based cohesive peridynamics method (CPDM) to simulate inelastic fracture of stiffened plates in ship hull structures

In this work, we utilize a non-local bond-based cohesive peridynamics method (CPDM) that is recently developed in Han et al. (2022) to model and simulate crack growth and crack propagation in stiffened plates, and to predict inelastic fracture processes in extensively-used stiffened plates in ship hull structures.The bond-based cohesive peridynamics method has both normal and tangential components in the bond force density, which allow for capturing of inelastic fracture processes under large deformation, and it is capable of the description of complex nonlinear material constitutive behaviors.By doing so, we have systematically simulated the fracture of stiffened plates with different types of stiffeners, such as rectangular, I-shaped, and L-shaped. Moreover, we also studied the strength effects of different sizes, layouts, and shapes of stiffeners on the fracture of plates. In specific, we calculated the structure stress intensity factors for various stiffened plate structures and study the crack arrest effect for various types of stiffeners on the hull structures. The numerical results demonstrate that bond-based cohesive peridynamics provides an accurate and reliable modeling and simulation tool for studying the structural failure mechanism of ship hull structures and predicting crack growth in stiffened plates.

Bending properties of carbon fiber reinforced composite multilayer damping structures with different types of stiffeners

Carbon fiber reinforced composite multilayer damping structures with different types of stiffeners demonstrate excellent mechanical properties. This paper deals with the bending properties analysis of carbon fiber reinforced composite multilayer damping structures with different types of stiffeners for the first time. A theoretical model was constructed to investigate the bending performance of the structure under static loading based on structural stress transfer mechanism between stiffener and composite plate. Moreover, the theoretical solution was compared with the numerical simulation results to confirm their validity. Finally, structural parameters were considered to discuss the change law of the structural center deflection.

Structural Performance of Internally Stiffened Double-Skinned Profiled Composite Walls with Openings

The double-skin profiled composite wall (DSPCW) system, filled with concrete material, is favorable in modern structures due to its high strength and ductility. Openings may be required within this composite wall (DSPCW) for various reasons, similar to a conventional bearing wall, which can lead to a reduction in bearing capacity. Therefore, to avoid changes in the geometry, materials, and thickness of this DSPCW wall, a new internally stiffening concept has been suggested by providing embedded cold-formed steel tube (CFST) columns. For this purpose, two full-scale DSPCW specimens were tested under static axial load, one of which was fabricated with a large opening size and stiffened with two octagonal CFST columns, while the other was designed without an opening and served as a control wall specimen. The results showed that the stiffened DSPCW with an opening achieved a slightly lower ultimate bearing strength (−9.4%) than the control wall specimen, with no reduction in the ductility behavior. Furthermore, several finite element models of DSPCW have been analyzed and designed to investigate additional parameters that were not experimentally tested, including the effects of the embedded CFST column’s shape and different types of internal stiffeners longitudinally provided inside these columns. The numerical investigation confirmed that the embedded CFST column with an octagonal cross-section was more efficient compared to the hexagonal and rectangular shapes by about 11% and 18.4%, respectively. Furthermore, using internal steel stiffeners for embedded tubes with a T-shape improved the axial bearing capacity of the DSPCW with an opening slightly higher than the corresponding stiffened walls with other investigated stiffener shapes (V-shaped, U-shaped, and L-shaped).

Comparison and design of stiffened rectangular concrete-filled steel tubular members

A stiffened rectangular concrete-filled steel tubular (CFST) member offers improved composite action over the unstiffened counterpart in terms of delaying local buckling of the rectangular steel tube and enhancing confinement to the infilled concrete, and thus various stiffening forms were proposed. Choosing an appropriate stiffener in practical design needs comprehensive understanding and comparison on the efficiency of various stiffeners. However, most studies focused on a single type of stiffener only, no guidance was provided on how to account for the benefits of stiffened rectangular CFST members in mainstream design specifications, and no unified calculation method for load capacity was formed. In this work, finite element models for stiffened rectangular CFST members were established and verified by test results. Then parametric analyses were conducted to compare the axial compressive and flexural behavior of rectangular CFST members with various types of stiffeners. The appropriate arrangement and detailing of stiffeners were proposed, and the diagonal ribs showed the best performance under the same material strength and steel consumption. Finally, mechanics-based models and unified calculation methods were proposed to calculate the axial compression and interaction strength, and were found to well predict the strength of stiffened and unstiffened CFST members. These results will further facilitate the use of stiffened rectangular CFST members in practical engineering projects.

Numerical Study of Castellated Beam with Stiffener – Case on Cantilever Structure

A castellated beam is designed to increase the depth of the beam by slicing the beam web longitudinally in a specified form and re-unite both pieces using welding to obtain a higher flexural capacity of the beam. Due to the increase in cross-sectional height and the presence of openings in the web plate, some potential failures may occur, for example buckling of the web and stress concentration on the opening. Addition of stiffener on the web is useful to prevent those potential failures. This paper presented a numerical study of castellated beam with additional stiffeners which is applied on a cantilever structure using MSC Nastran software. The castellated beam was added by stiffeners placed on three different zones. There were stiffeners on the perimeter of opening, on the web between openings, and on the web of opening. The cantilever beam was subjected by a point load increased monotonically until ultimate condition reached. It was found that applying of the stiffeners on perimeter of opening will increase ultimate load up to 7.48 % comparing to the original castellated beam. On contrary, stiffeners on the web between openings and the web of opening will decrease the ultimate load within the range of 0.40% - 4.86 %. The beam stiffness will slightly increase because of these three types of additional stiffeners. Regarding ductility of the beams, adding of stiffeners on the castellated beam showed vary numbers. Overall, the stiffeners on perimeter of opening become an alternative to increase the performance of the castellated beam in term of the ultimate load, beam stiffness and ductility.

Web Bend-Buckling of Steel Plate Girders Reinforced by Two Longitudinal Stiffeners with Various Cross-Section Shapes

This work performs an investigation into the optimal position of two longitudinal stiffeners with different cross-section shapes such as open section (L-shaped and T-shaped) and closed section (rectangular and triangular shapes) shapes of stiffened plate girders under bending loading through an optimization procedure using a gradient-based interior point (IP) optimization algorithm. The stiffener optimum locations are found by maximizing the bend-buckling coefficient, kb, generated from eigenvalue buckling analyses in Abaqus. The optimization procedure efficiently combines the finite element method and the IP optimization algorithm and is implemented using the Abaqus2Matlab toolbox which allows for the transfer of data between Matlab and Abaqus and vice versa. It is found that the proposed methodology can lead to the optimum design of the steel plate girder for all stiffener cross-section types with an acceptable accuracy and a reduced computational effort. Based on the optimization results, the optimum positions of two longitudinal stiffeners with various cross-section shapes are presented for the first time. It is reported that the optimum locations of two longitudinal stiffeners with open cross-section shapes (T- and L-shaped) are similar to that of flat cross-section, while the optimum positions of two longitudinal stiffeners with closed cross-section types (rectangular and triangular sections) are slightly different. One of the main findings of this study is that the bend-buckling coefficient of the stiffened girder having stiffeners with triangular cross-section shape is highest while that with flat cross-section shape is lowest among all considered stiffener types and this latter case has minimum requirement regarding the web thickness.

Finite Element Analysis of a Semi-Rigid Endplate Beam-to-Column Joint with Stiffeners

This article examines the mechanical behavior of steel endplate beam-to-column joints with different stiffeners under bending moment. This type of connection is commonly used in steel frameworks to transmit loads from beams to columns. In frame design procedures, engineers tend to consider beam-to-column joints either ideally pinned or fully rigid. The present study aims to show their semi-rigid behavior by analyzing the characteristics of the relation between the bending moment and the rotation of the studied connection. The analysis is based on the development of a finite element model considering the material, geometrical and contact nonlinearities between the components. Three types of stiffeners are introduced in different positions to investigate their effect on the global behavior of the joints. The moment rotation curve is defined together with the procedure of determination of the initial rotational stiffness, the elastic and plastic moments of the connection. The numerical model is validated by comparing the moment rotation curves with those of similar studies available in the literature and also with the design approach proposed by Eurocode 3. The obtained results have showed that the use of stiffeners in the column web or on the endplate increases significantly the rigidity of the studied connection. The failure modes have been discussed in detail for each configuration with respect to the rotation capacity and the initial stiffness. Finally, the model has been used to show the influence of three bolts classes on the ultimate load of the joints and the deformation of the endplate and bolts at failure.

Assessing Effectiveness of Shape Memory Alloys on the Response of Bolted T-Stub Connections Subjected to Cyclic Loading

This study presents finite element analysis of double split tee (DST) connections with high-strength steel bolts and coupled split tee sections, to evaluate various cyclic response parameters and elements. The investigation included quantifying connection behavior and hysteretic response, damage indexes, and failure modes. Over 40 specimens were simulated in ABAQUS under cyclic loading, including shape memory alloy (SMA)-built specimens. In the post-analysis phase, the T-stub thickness, the T-stub yield strength, the bolt preload and bolt number, and the stiffener type and stiffener material for the most significant parts of the DST connection were calculated. Simulation results showed that a lower ultimate moment yielded fewer needed stem bolts. The energy dissipation (ED) capacity increased as the horizontal distance between the stem bolts decreased. Additionally, increasing the strength of the bolt and T-stub by 15% resulted in a 3.86% increase in residual displacement (RD) for the bolt and a 1.73% decrease in residual displacement for the T-stub. T-stub stiffeners enhanced ED capacity by 31.7%. SMA materials were vulnerable to mode 1 failure when used in T-stubs, bolts, or stiffeners. However, the use of SMA increased the rate of energy dissipation. Adding stiffeners to the T-stubs altered the failure indexes and improved the pattern of failure modes. In addition, stiffeners decreased the rupture and pressure indexes. As a result, the failure index of a T-stub shifted from brittle failure to ductile failure.

New cross-sectional slenderness limits for stiffened rectangular concrete-filled steel tubes

Rectangular concrete-filled steel tubes (RCFST) are efficient structural members that exhibit good strength, stiffness, and ductility. The mechanical properties of RCFST can be further enhanced by the addition of internal stiffeners which delay local buckling of the tube, improve load transfer, and can confine the concrete. Numerous experimental and analytical studies have been performed to characterize the behavior of stiffened RCFST. However, most studies focus on a single type of stiffener. Also, most major design standards do not provide guidance on how to account for the beneficial effects of the stiffeners. The objective of this work was to develop strength design recommendations for short stiffened RCFST columns and beam-columns that are applicable to a variety of stiffener types. A database of previously published experimental tests on stiffened RCFST members was compiled and the experimental results were compared to American, European, and Chinese design standards. Each of these standards employs the plastic stress distribution method for filled composite members that are not susceptible to local buckling as identified using cross-sectional slenderness ratio limits. The results indicate that neglecting the stiffeners is unnecessarily conservative. New cross-sectional slenderness ratio limits are proposed for stiffened RCFST, allowing a greater range of members to be assessed using the plastic stress distribution method. These results provide strong justification for changes to design standards to recognize the benefits of highly efficient stiffened RCFST members.

Effect of The Haunch Angle and Stiffener Types on Column-Beam Connection Behaviour Under Static Loading

The strong column-weak beam principle, one of the earthquake resistant building design theories, require the connection area to be strong enough so that the plastic hinge forms in the beam. One of the proposed solutions is to strengthen the column-beam connection zone in steel connection with haunches. This study aims to look at parametrically behavior of column-beam haunched connections under the 100mm vertical displacement controlled loading using the finite element method. To obtain this, a total number of 21 finite elements model with 15, 30, and 45 degrees angles and 6 various stiffener types has been modeled by ABAQUS software. The research later discussed behavior of underlying components of haunch connections models such as the load-displacement curve, bearing capacity, extended end plate bending, stress distribution, and the position of the plastic hinge's development after finite element analysis. The study found that decrease in haunch angle improve the connection's bearing capacity, while in this case, the failure modes and plastic hinges will occur close to the joints which does not meet the code requirements. The article concludes that the 30-degree haunch angle is the most appropriate one in haunch connection and the three parallel and K-stiffeners is the most suitable reinforcement type for the haunched connections.

Experimental and numerical study of prefabricated steel frame with integrated wall panels

The suitability of external integrated lightweight thermal insulation decorative wall panels as a fully bolted prefabricated steel frame enclosure system was studied. The test on the fully bolted prefabricated steel frame with the external integrated lightweight thermal insulation decorative wall panels was completed under quasi-static cyclic loading, and the impact of the beam-column joint types were investigated. The failure mode, lateral stiffness, bearing capacity, energy dissipation capacity, ductility, and strain distribution were analyzed, and the internal forces of the steel frame were calculated. Experimental results show that the external integrated wall has minimal effect on the stiffness and bearing capacity of the fully bolted prefabricated steel frame. Furthermore, the L-shaped angle joints can increase the bearing capacity, energy dissipation capacity, and lateral stiffness evidently and move the joint plastic hinge outwards. The differences between the experimental bearing capacity and the theoretical value of the steel frame were minimal. Significant buckling deformation was observed at the beam-end, and progressive full-field strain at the plastic hinge were distributed in a band shape. The corresponding improved design was proposed. In addition, the failure mode and hysteretic behavior of the structures were studied by finite element analysis, and the influence of the main parameters, such as the number of horizontal and vertical plate bolts, the types of L-shaped angle stiffeners, and the height-span ratio and axial compression ratio of steel frame were discussed. The finite element analysis results were consistent with those of the test. It provided theoretical evidence for the design and application of fully bolted prefabricated steel frame with external integrated lightweight wall panels.

Preliminary Design of Traditional Fishing Boat (2 GT) With Additional Floating Compartment for Safety Reasons Using BKI Rules

t raditional fishing boats are used by fishermen for finding fish to support their daily lives. Because there are many shortcomings in their boats (design problems) and natural conditions that often change, accidents can occur which cause their boats to easily overturn and sink to the bottom of the sea. Other problems were also encountered, such as the boat's obstacles , and the boat's floating compartment was not well designed. For this reason, the author conducted research on the design of a fishing boat with a floating compartment using the BKI rules. Using one of the existing boats was made as a design reference with boat sizes. The principal dimension of the fishing boat is LOA: 10.15 m, Lwl: 8,996 m, B: 1 m, H: 0.87 m, H: 0.3 m, and 2 GT. The results of the calculations find that the engine specification that suits the fishing boat is 3.5 kW with a speed of 7 knots. The author's research varies the Flo o dable Length of the original boat's floating compartment with a compartment size of 1.365 m AP, 1.325 m FP, and model 2 floating compartment using BKI rules with AP size 2.225 m and FP 2.425 m. The analysis result based on the design of the fishing boat shows that model 2 is the best design. C onstruction in accordance with BKI regulations, a mixed type of construction was chosen. The frame distance is 500 mm with the stiffener type model h = 25 mm, bb = 30 mm, and bc = 36 mm. Meanwhile, the total stringer is 6 stiffeners.