scholarly journals On the Limit Behaviour of Moment Resisting Connections Under Uncertainties

2021 ◽  
Vol 1203 (3) ◽  
pp. 032081
Author(s):  
Salvatore Benfratello ◽  
Santo Vazzano
Keyword(s):  
Bending Strength ◽  
Structural Member ◽  
Material Strength ◽  
Special Device ◽  
Structural Behaviour ◽  
Design Strength ◽  
Moment Capacity ◽  
Full Strength ◽  
Moment Resisting ◽  
Geometrical Dimensions

Abstract Moment resisting connections are mainly designed to transfer bending moments and shear forces. Generally speaking, the design strength of a moment resisting connection can be classified as full-strength (moment capacity of the connection equal to or greater than that of the connected member) or partial-strength (the moment capacity of the connection less than that of the connected member). Similar remarks can be made regarding the stiffness defining connection rigid or semi-rigid if compared to the stiffness of the connected member. In the past, full-strength connections have been widely adopted especially in moment resisting frames and their structural performance relied on the proper behaviour of welding. However, the research following the 1994 Northridge and 1995 Kobe earthquakes demonstrated the lower than expected performance of welded connections, stimulating the onset and development of pre-qualified connections to be adopted especially in seismic areas. Among these connections the most studied ones are those belonging to the Reduced Beam Section (RBS) typology, being the so-called “dogbone” connection the most adopted. The dogbone presents a bending strength and a flexural stiffness lesser than the ones of the original structural member. Recently, the authors proposed a special device suitably designed to realize an innovative moment resisting connection for steel beam elements belonging to the RBS typology. Such a device, called Limited Resistance Plastic Device (LRPD), is constituted by three different portions: the central one is devoted to the onset and development of plastic deformations and presents geometrical dimensions reduced with respect to those of the original structural member; the external ones are devoted to recover the stiffness of beam-device system to that of the original structural member and present greater geometrical dimensions. This latter remark allows to affirm that, from a connectivity point of view, the stiffness of LRPD at the column-beam interface, is greater than the one of the original structural member. Another fundamental remark is that the structural connections are intrinsically characterized by uncertainties related either to geometrical or to material ones. Usually, the effect of uncertainties is covered by the use of safety coefficients and the analyses are performed referring only to the nominal values of the geometrical and mechanical characteristics. However, in order to perform a more complete interpretation of the mechanical behaviour of the studied connections, a non-deterministic analysis approach can be used. Aim of the paper is the characterization of the structural behaviour of the referenced connections (“dogbone” and LRPD) taking into account the main geometrical uncertainties and that related to the material strength by performing suitably Monte Carlo simulations and by determining the relevant M-N domains. Starting from the described characterization, different commercial steel profiles will be considered in order to build a series of M-N domains useful to quantify the safety level and the range of usability of the two different RBS approaches. Finally, the implemented applications will lead to demonstrate the greater reliability of LRPD compared to the classical dogbone.

scholarly journals Iterative Optimal Design of Special Moment Resisting Devices for Steel Frames

2021 ◽  
Vol 1203 (3) ◽  
pp. 032079
Author(s):  
Luigi Palizzolo ◽  
Santo Vazzano
Keyword(s):  
Optimal Design ◽  
Iterative Procedure ◽  
Bending Strength ◽  
Bending Moment ◽  
Elastic Stiffness ◽  
Steel Frame ◽  
Special Device ◽  
Structural Behaviour ◽  
Good Reliability ◽  
Moment Resisting

Abstract The present paper proposes an iterative procedure devoted to reaching the optimal design of an innovative, recently proposed, moment resisting device. This special device, called Limited Resistance Plastic Device (LRPD), can be utilized, as an example, to equip a steel frame when it is required that the frame must be designed to substitute a masonry panel, i.e., it must be characterized by a structural behaviour as close as possible to the one of the replaced masonry wall. This purpose can be reached by designing the relevant frame imposing appropriate constraints on the elastic stiffness and on the limit resistance. The result can be obtained just by ensuring that the elastic stiffness and the limit resistance be independent of each other. To this aim it is necessary to suitably equip the steel frame by the previously cited LRPD. In particular, these moment resisting connections ensure that in a prefixed portion of the given beam element, the limit bending moment reduces without any variation of the global elastic stiffness. In order to reach this goal, the LRPD is substantially constituted by an inner portion, devoted to exhibit the desired reduced limit bending strength and to receive the plastic deformations, and two outer portions, devoted to guarantee the invariance of the elastic bending stiffness. The proposed iterative procedure allows to design a device respecting all the required features avoiding the presence of any dangerous local instability phenomenon. To this aim, the design will contain appropriate constraints ensuring that the device cross sections appertain to class 1 or class 2 I-cross section, as prescribed in the more recent standard codes. Some examples, validated by 3D solid tetrahedral elements analysis in ABAQUS environment, prove the good reliability of the proposed procedure and show the easy applicability of the computational approach.

Structural Behaviour of Blind Bolted Connection to Concrete-Filled Steel Tubular Columns

2010 ◽  
Vol 163-167 ◽  
pp. 591-595
Author(s):  
Jing Feng Wang ◽  
Xin Yi Chen ◽  
Lin Hai Han
Keyword(s):  
Analysis Model ◽  
Bolted Connections ◽  
Structural Behaviour ◽  
Tubular Columns ◽  
End Plate ◽  
Moment Resisting ◽  
Strength And Stiffness ◽  
Plate Connections ◽  
The Moment ◽  
Plate Connection

This paper studies structural behaviour of the blind bolted connections to concrete-filled steel tubular columns by a serial of experimental programs, which conducted involving eight sub-assemblages of cruciform beam-to-column joints subjected to monotonic loading and cyclic loading. The moment-rotation hysteretic relationships and failure models of the end plate connections have been measured and analyzed. A simplified analysis model for the blind bolted connections is proposed based on the component method. It is concluded that the blind bolted end plate connection has reasonable strength and stiffness, whilst the rotation capacity of the connection satisfies the ductility requirements for earthquake-resistance in most aseismic regions. This typed joint has excellent seismic performance, so it can be used in the moment-resisting composite frame.

Elastic Strength of Defective Steel Bolt Group under Eccentric Load Design

2018 ◽  
Vol 773 ◽  
pp. 299-304
Author(s):  
Jen Jen Yang ◽  
Kun Ze He ◽  
Wei Ting Hsu
Keyword(s):  
Geometric Distribution ◽  
Design Method ◽  
Group Analysis ◽  
Steel Structure ◽  
Steel Structures ◽  
Strength Analysis ◽  
Material Strength ◽  
Eccentric Load ◽  
Critical Position ◽  
Design Strength

Steel bolt groups are often used for joining steel structures. The design strength of the steel bolt group is related to the geometric distribution, the eccentric load distance, the material strength and the load angle, thus making the analysis complicated and not easy for the user. The existing analysis methods are two kinds of elasticity and ultimate analysis. Both methods consider the stress distribution of each steel bolt and find the steel bolt at the critical position is obtained, the design load analysis is deduced. This study will consider the geometric distribution of steel bolting group affected, for a row, two rows, three rows and four rows of bolt group, considering different eccentric distance and angle of influence. Using a simple elastic analysis method to Studied the strength analysis results produced when a corner bolt is damaged due to a defect. The results show that the greater the eccentric load distance, the lower the design strength, and the load change on the vertical is more obvious than the horizontal. When the corner of the steel bolt group is removed, its design strength is likely to decrease, but at low eccentricity distance and large angles, the strength of the complete bolt is higher. This study organizes the design method of steel bolts and reviews the geometric rules of the bolt group analysis. It founded that the regular geometry needs to be reviewed in the case of large eccentric loads with small eccentricities. This study for the bolt connections strength of a certain understanding and awareness, expect the future for the safety of steel structure contribute.

scholarly journals CALCULATING THE CARRYING CAPACITY OF FLEXURAL PRESTRESSED CONCRETE BEAMS WITH NON-METALLIC REINFORCEMENT

2010 ◽  
Vol 2 (6) ◽  
pp. 5-13
Author(s):  
Mantas Atutis
Keyword(s):  
Prestressed Concrete ◽  
Concrete Beams ◽  
Steel Reinforcement ◽  
Elastic Response ◽  
Structural Behaviour ◽  
Moment Capacity ◽  
Calculation Results ◽  
Fibre Reinforced Polymer ◽  
Frp Reinforcement ◽  
Metallic Reinforcement

The article reviews moment resistance design methods of prestressed concrete beams with fibre-reinforced polymer (FRP) reinforcement. FRP tendons exhibit linear elastic response to rupture without yielding and thus failure is expected to be brittle. The structural behaviour of beams prestressed with FRP tendons is different from beams with traditional steel reinforcement. Depending on the reinforcement ratio, the flexural behaviour of the beam can be divided into several groups. The numerical results show that depending on the nature of the element failure, moment resistance calculation results are different by using reviewed methods. It was found, that the use of non-metallic reinforcement in prestressed concrete structures is effective: moment capacity is about 5% higher than that of the beams with conventional steel reinforcement.

scholarly journals Strength Reliability of Micro Polycrystalline Silicon Structure

2007 ◽  
Vol 345-346 ◽  
pp. 777-780
Author(s):  
Shigeru Hamada ◽  
Kenji Hashizume
Keyword(s):  
Polycrystalline Silicon ◽  
Microelectromechanical Systems ◽  
Bending Strength ◽  
Chemical Vapor ◽  
Material Strength ◽  
Mems Devices ◽  
Bending Tests ◽  
Average Value ◽  
Micron Size ◽  
Mechanical Movement

In order to evaluate strength reliability of micron size polycrystalline silicon (poly-Si) structure, bending tests of cantilever beam and Weibull analysis are performed. Recently, the importance of microelectromechanical systems (MEMS) in society is increasing, and the number of production is also increasing. The MEMS devices, which contain mechanical movement, have to maintain their reliability in face of external shock, thermal stress and residual stress from manufacturing processes. In greeting the mass production era of the MEMS, in case the material strength design of MEMS is performed, required strength data is not average value but the variation, especially minimum value of the material. Micron size poly-Si structure is widely employed in the MEMS such as microsensor, switching device and so on. Then, in order to evaluate strength reliability of micron size poly-Si structure, tests and analysis are performed. The specimen is made by chemical vapor deposition (CVD) process and thickness is 3.5, 6.4 and 8.3 micrometer and the specimen has notch. The test specimen used for the test changed characteristics of (1) film thickness (2) stress concentration, and investigation about the influence each effects of the variation in a bending strength are discussed.

scholarly journals Numerical Evaluation of Structural Safety for Aged Onshore Wind Foundation to Extend Service Life

2020 ◽  
Vol 10 (13) ◽  
pp. 4561
Author(s):  
Youn-Ju Jeong ◽  
Min-Su Park ◽  
Sung-Hoon Song ◽  
Jeongsoo Kim
Keyword(s):  
Fatigue Life ◽  
Service Life ◽  
Safety Evaluation ◽  
Life Extension ◽  
Structural Safety ◽  
Material Strength ◽  
Design Strength ◽  
Onshore Wind ◽  
Service Period ◽  
Service Life Extension

In this paper, for the case of “service life extension” with the same capacity for wind turbines, a structural safety evaluation was carried out to determine whether to extend the service life of the aged foundation. As a result of this study, it was found that the aged foundation satisfies the structural safety of material strength, ultimate strength, fatigue life, and serviceability up to the present. Although the in-service period has been over 16 years, it has been shown that the material properties of concrete have exceeded the design strength, and no significant material deterioration has occurred. Also, structural safety could be evaluated more realistically based on actual concrete properties. In particular, it has been shown that it has a fatigue life of 40 years or more, so service life can be extended. It is expected that the methodology used in this paper will be useful not only for structural safety evaluation of the foundation in service, but also for decision-making for extending the service life. Furthermore, a more technical approach should be explored by many researchers in the future.

BEHAVIOUR OF ECCENTRICALLY LOADED SLENDER CONCRETE FILLED STEEL TUBES COLUMNS

2016 ◽  
Vol 78 (5-4) ◽  
Author(s):  
Clotilda Petrus ◽  
Hanizah Abd Hamid ◽  
Azmi Ibrahim ◽  
Joe Davylyn Nyuin
Keyword(s):  
Applied Load ◽  
Bending Strength ◽  
Structural Behaviour ◽  
Steel Tubes ◽  
Longitudinal Stiffeners ◽  
Different Types ◽  
Thin Walled ◽  
Slender Column ◽  
Overall Buckling ◽  
Concrete Filled Steel Tubes

This paper presents an experimental investigation into the structural behaviour of eccentrically loaded concrete filled, thin walled, steel tubular slender column with tab stiffeners (CFST). The primary parameters studied through the experimental work are load eccentricity and type of stiffeners. Three different types of stiffeners used in this study are longitudinal stiffeners of 10mm height, longitudinal and tab stiffeners of 25mm height and longitudinal and extended tab stiffeners at 40mm. The effects of the stiffeners on the structural behavior were investigated experimentally using 26 specimens of slender CFST, loaded with eccentricity ranging from 0 mm to 60 mm. It was observed that all specimens failed mainly by overall buckling and, the compressive strength and bending strength of the specimens decreases as the applied load eccentricity increases.

Comparison of steel strength retention models for fire exposed concrete slabs

2021 ◽  
Author(s):  
Thomas Thienpont ◽  
Ruben Van Coile ◽  
Robby Caspeele ◽  
Wouter De Corte
Keyword(s):  
Reinforced Concrete ◽  
Construction Materials ◽  
Structural Response ◽  
Bending Moment ◽  
Concrete Slabs ◽  
Structural Behaviour ◽  
Moment Capacity ◽  
Retention Models ◽  
Reinforced Concrete Slabs ◽  
Strength Retention

<p>In structural fire engineering, there is a growing trend towards the use of performance based approaches to evaluate structural behaviour during or after a fire. Consequently, there is a need for an increased level of confidence in properties of construction materials used in these performance based approaches. Both steel and concrete have been experimentally observed to show a dispersal in the value of their respective structural strengths, at room temperature, but more significantly at high temperatures. In this paper the influence of three temperature dependent strength retention models for reinforcement steel on the bending moment capacity of simply supported reinforced concrete slabs exposed to a standardized fire is analysed. The results show that the structural response of reinforced concrete slabs strongly depends on the chosen probabilistic model, thus highlighting the importance of appropriate model selection.</p>

scholarly journals Influence of Beam-to-Column Linear Stiffness Ratio on Failure Mechanism of Reinforced Concrete Moment-Resisting Frame Structures

2020 ◽  
Vol 2020 ◽  
pp. 1-24
Author(s):  
Jizhi Su ◽  
Boquan Liu ◽  
Guohua Xing ◽  
Yudong Ma ◽  
Jiao Huang
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Numerical Models ◽  
Frame Structures ◽  
Material Strength ◽  
Stiffness Ratio ◽  
Limit Values ◽  
Failure Patterns ◽  
Moment Resisting Frame ◽  
Moment Resisting

The design philosophy of a strong-column weak-beam (SCWB), commonly used in seismic design codes for reinforced concrete (RC) moment-resisting frame structures, permits plastic deformation in beams while keeping columns elastic. SCWB frames are designed according to beam-to-column flexural capacity ratio requirements in order to ensure the beam-hinge mechanism during large earthquakes and without considering the influence of the beam-to-column stiffness ratio on the failure modes of global structures. The beam-to-column linear stiffness ratio is a comprehensive indicator of flexural stiffness, story height, and span. This study proposes limit values for different aseismic grades based on a governing equation deduced from the perspective of member ductility. The mathematical expression shows that the structural yielding mechanism strongly depends on parameters such as material strength, section size, reinforcement ratio, and axial compression ratio. The beam-hinge mechanism can be achieved if the actual beam-to-column linear stiffness ratio is smaller than the recommended limit values. Two 1/3-scale models of 3-bay, 3-story RC frames were constructed and tested under low reversed cyclic loading to verify the theoretical analysis and investigate the influence of the beam-to-column linear stiffness ratio on the structural failure patterns. A series of nonlinear dynamic analyses were conducted on the numerical models, both nonconforming and conforming to the beam-to-column linear stiffness ratio limit values. The test results indicated that seismic damage tends to occur at the columns in structures with larger beam-to-column linear stiffness ratios, which inhibits the energy dissipation. The dynamic analysis suggests that considering the beam-to-column linear stiffness ratio during the design of structures leads to a transition from a column-hinge mechanism to a beam-hinge mechanism.

Response sensitivity of blast-loaded reinforced concrete structures to the number of degrees of freedomThis article is one of a selection of papers published in the Special Issue on Blast Engineering.

2009 ◽  
Vol 36 (8) ◽  
pp. 1305-1320 ◽  
Author(s):  
W. W. El-Dakhakhni ◽  
S. H. Changiz Rezaei ◽  
W. F. Mekky ◽  
A. G. Razaqpur
Keyword(s):  
Reinforced Concrete ◽  
Degrees Of Freedom ◽  
Failure Modes ◽  
Structural Member ◽  
Degree Of Freedom ◽  
Material Strength ◽  
Nonlinear Behaviour ◽  
Structural Members ◽  
Accurate Analysis ◽  
Rc Structures

Accurate analysis of reinforced concrete (RC) structures under blast loading is very complicated due to the nonlinear behaviour of concrete and reinforcement and the various failure modes to be considered. Although blast loads can excite a large number of modes due to their high frequency content, practical computational tools are usually limited to single-degree-of-freedom (SDOF) models. In addition to oversimplification, SDOF models are known to give inaccurate prediction for shear forces and support reactions. This is because accurate shear force prediction typically requires accounting for modes higher than the fundamental mode. In this study, a multi-degree-of-freedom (MDOF) model is developed that takes into account the nonlinear behaviour of RC structures and the material strength and deformation dependency on the strain rate. Using this model, a series of dynamic analyses were carried out for two typical structural members, with different combination of blast pressure and impulse. The effect of varying the number of degrees of freedom (DOF) was investigated through increasing the number of nodes used to descretize each structural member. The results of the developed MDOF model were compared to the results of available SDOF models which demonstrated the deficiencies of the latter. The developed MDOF model, with few DOF, was found to be capable of accurately predicting the dynamic shear of the modeled structural members. The model was also compared to available experimental results and showed good agreement. Changing the number of DOF also affected the pressure–impulse (P–I) diagrams for the structural member significantly, especially in the impulsive regime.

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