Experimental Tests on Extended Stiffened End-Plate Joints within Equal Joints Project

2018 ◽  
Vol 763 ◽  
pp. 406-413 ◽  
Author(s):  
Mario D'Aniello ◽  
Roberto Tartaglia ◽  
Silvia Costanzo ◽  
Giuseppe Campanella ◽  
Raffaele Landolfo ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Experimental Tests ◽  
The Other ◽  
Analytical Models ◽  
Project Design ◽  
Design Rules ◽  
Steel Moment Resisting Frames ◽  
End Plate ◽  
Other Hand ◽  
Moment Resisting

Bolted extended stiffened end-plate beam-to-column joints are commonly used for steel moment resisting frames in seismic areas. In the framework of European codes, EN 1993:1-8 provides the design rules and the analytical models to predict the mechanical behavior of the joints. On the other hand, EN 1998-1 specifies the required performance for seismic resistant joints. Within EQUALJOINTS project design rules have been developed and experimental tests were carried out to seismically prequalify extended stiffened end-plate joints. In this paper the proposed design rules are discussed and results of the experimental tests are described.

Effect of Specimen Geometry on the Predicted Mechanical Behavior of Polyethylene Pipe Material

2014 ◽  
Author(s):  
Tarek M. A. A. El-Bagory ◽  
Tawfeeq A. R. Alkanhal ◽  
Maher Y. A. Younan
Keyword(s):  
Mechanical Behavior ◽  
Longitudinal Direction ◽  
Primary Objective ◽  
The Other ◽  
Pipe Material ◽  
Ring Specimen ◽  
Design Data ◽  
Practical Applications ◽  
Other Hand ◽  
Gauge Section

The primary objective of the present paper is to depict the mechanical behavior of high density polyethylene, (HDPE), pipes under different loading conditions with different specimen geometries to provide the designer with reliable design data relevant to practical applications. Therefore, it is necessary to study the effect of strain rate, ring configuration, and grip or fixture type on the mechanical behavior of dumb-bell-shaped, (DBS), and ring specimens made from HDPE pipe material. DBS and ring specimens are cut from the pipe in longitudinally, and circumferential (transverse) direction respectively. On the other hand, the ring specimen configuration is classified into two types; full ring, (FR), and notched ring, (NR) (equal double notch from two sides of notched ring specimen) specimens according to ASTM D 2290-12 standard. Tensile tests are conducted on specimens cut out from the pipe with thickness 10 mm at different crosshead speeds (10–1000 mm/min), and ambient temperature, Ta = 20 °C to investigate the mechanical properties of DBS, and ring specimens. In the case of test specimens taken from longitudinal direction from the pipe a necking phenomenon before failure appears at different locations along the gauge section. On the other hand, the fracture of NR specimens occurs at one notched side. The results demonstrated that the NR specimen has higher yield stress than DBS, and FR specimens at all crosshead speeds. The present experimental work reveals that the crosshead speed has a significant effect on the mechanical behavior of both DBS, and ring specimens. The fixture type plays an important role in the mechanical behavior for both FR and NR specimens at all crosshead speeds.

Influence of seismic design rules on the robustness of steel moment resisting frames

2016 ◽  
Vol 21 (3) ◽  
pp. 479-500 ◽  
Author(s):  
David Cassiano ◽  
Mario D'Aniello ◽  
Carlos Rebelo ◽  
Raffaele Landolfo ◽  
Luis S. da Silva
Keyword(s):  
Seismic Design ◽  
Design Rules ◽  
Steel Moment Resisting Frames ◽  
Moment Resisting Frames ◽  
Moment Resisting

scholarly journals Verification of prying effect in prestressed end-plate connection

2013 ◽  
Vol 12 (2) ◽  
pp. 251-258
Author(s):  
Krzysztof Ostrowski ◽  
Jan Łaguna ◽  
Aleksander Kozłowski
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
High Strength ◽  
Experimental Tests ◽  
Analytical Models ◽  
End Plate ◽  
Plate Connections ◽  
Plate Connection ◽  
Element Method

End-plate connections are very often used is steelwork, as tension and bending connections. As a result of deflection of end plate, additional forces, known as prying forces arise and consequently increase stresses in bolts. Eurocode 1993-1-8 do not distinguish end-plate connections prestressed by high strength bolts from non-prestressed. The aim of the paper is to perform the comparison of previous analytical models and code regulations for coefficient of prying forces to the experimental tests and modelling by finite element method. Results of the analysis show that the behaviour of prestressed connection is essentially different with comparison to non-prestressed.

Effect of Size-Dependent Cavitation on Micro- to Macroscopic Mechanical Behavior of Rubber-Blended Polymer

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Isamu Riku ◽  
Koji Mimura ◽  
Yoshihiro Tomita
Keyword(s):  
Surface Tension ◽  
Plastic Deformation ◽  
Mechanical Behavior ◽  
Volumetric Strain ◽  
Critical Value ◽  
The Other ◽  
Size Dependent ◽  
Other Hand ◽  
Blended Polymer ◽  
Onset Of Cavitation

In rubber-blended polymer, the onset of cavitation in the particles relaxes the high triaxiality stress state and suppresses the onset of crazing in the polymer. As a result, large plastic deformation is substantially promoted compared with single-phase polymer. On the other hand, it is also well known that the onset of cavitation depends on the size of particle. To investigate the size dependence of cavitation behavior in the particle, a theoretical analysis is done employing a void model under plane strain condition, which takes into account the surface tension and the limiting stretch of the void. Continuously, to study the effect of the size-dependent cavitation on the micro- to macroscopic mechanical behavior of the blend, a computational model is proposed for the blend consisting of irregularly distributed heterogeneous particles containing the void with surface force. The results indicate that when the size of the particle decreases to a critical value that depends on both the initial shear modulus of particle and the surface tension on the surface of void, the increase of the critical stress for the onset of cavitation becomes remarkable and consequently, the onset of cavitation is eliminated. When the particle is embedded in polymer, the relation between average normal stress, which is acting on the interface of particle and matrix, and volumetric strain of particle shows dependence on the size of particle but no dependence on the triaxiality of macroscopic loading condition. For the blend consisting of particles smaller than the critical value, the onset of cavitation is eliminated in particles and as a result, the conformation of the shape of particle to the localized shear band in matrix becomes difficult and the shear deformation behavior tends to occur all over the matrix. Furthermore, in this case, the area of the maximum mean stress is confined to the area adjacent to the particle and the value of it increases almost linearly throughout the whole deformation process, which would lead to the onset of crazing in matrix. On the other hand, it is clarified that the onset of cavitation is predominant in the localized microscopic region containing heterogeneous particles and therefore, the plastic deformation is promoted in this region.

Damage Avoidance Self-Centering Steel Moment Resisting Frames (MRFs) Using Innovative Resilient Slip Friction Joints (RSFJs)

2018 ◽  
Vol 763 ◽  
pp. 726-734 ◽  
Author(s):  
Ashkan Hashemi ◽  
Pouyan Zarnani ◽  
Farhad Mohammadi Darani ◽  
Armin Valadbeigi ◽  
George Charles Clifton ◽  
...  
Keyword(s):  
Experimental Tests ◽  
Steel Moment Resisting Frames ◽  
Residual Drift ◽  
Moment Resisting Frames ◽  
Moment Resisting ◽  
Gap Opening ◽  
Ductile Behavior ◽  
Design Earthquake ◽  
Determining Factor ◽  
Damage Avoidance

Higher seismic performance can be achieved by localizing the inelastic deformation in the connections (fuses) and minimizing the residual drift that are often a determining factor in whether a structure can be repaired or re-occupied after an earthquake. This paper introduces the self-centering damage avoidance steel Moment Resisting Frames (MRFs) using innovative Resilient Slip Friction Joints (RSFJs). The RSFJ provides self-centering and energy dissipation in one compact package requiring no post-event maintenance. In this concept, the beam is connected to the column through a pinned joint at the top, an RSFJ at the bottom and a slotted web plate for transferring the shear forces, when required. The RSFJ allows for gap opening in the connection upon loading and then re-centers the system when unloading. Furthermore, a secondary fuse within the RSFJ is considered to keep maintaining a ductile behavior in the system in case of an earthquake larger than the design earthquake. The conducted experimental tests confirmed the outcomes of this study.

scholarly journals Confinement of Masonry Columns with the FRCM-System: Theoretical and Experimental Investigation

2020 ◽  
Vol 5 (11) ◽  
pp. 101
Author(s):  
Maria Antonietta Aiello ◽  
Alessio Cascardi ◽  
Luciano Ombres ◽  
Salvatore Verre
Keyword(s):  
Experimental Investigation ◽  
Stress Transfer ◽  
Experimental Results ◽  
The Other ◽  
Analytical Models ◽  
Small Scale ◽  
Structural Element ◽  
Technical Literature ◽  
Number Of Layers ◽  
Other Hand

Fabric Reinforced Cementitious Matrix (FRCM) systems are promising solutions for the confinement of masonry columns because they demonstrate strengthening effectiveness and, at the same time, compatibility with historical substrates. Nevertheless, the matrix is responsible for the stress-transfer from the structural element to the fabric-reinforcement. Therefore, in the case of poor-quality mortar, the effectiveness of the strengthening can be limited or even compromised. On the other hand, the low content of fibers utilized for FRCM systems generally involves the need to apply more layers in order to accomplish design requirements and a continuous configuration of the reinforcement is more often addressed. Few experimental and theoretical investigations have been targeted to the before mentioned aspects in the recent past, namely the influence of the kind of mortar, the number of layers, and the strengthening configuration (continuous, discontinuous) on the effectiveness of confinement. The present paper refers to the results of an experimental investigation on FRCM confined clay brick masonry. A series of small-scale masonry columns were tested under monotonic centered load until collapse. The varied parameters were the number of confining layers (i.e., 1, 2, and 3) and the confinement configuration (i.e., continuous and discontinuous). The performed research aims to contribute in strengthening to the knowledge in the field of FRCM-confinement, mainly focusing on some of the mentioned unexplored aspects (number of layers, strengthening configuration) that could be considered for validation/improvement of analytical design-oriented formulas. In particular, some analytical models, available in the technical literature, were adopted for predicting the herein reported experimental results. Even if based on few experimental results, the outcomes showed that the number of FRCM-layers and the confinement configuration were crucial parameters affecting the confining effectiveness. The compressive strength was satisfactorily predicted in all cases by the two available utilized models. On the other hand, an improvement in the utilized AOM model is suggested in order to include the stress–strain curves of the hardening type.

Unusual Effect of Oxygen on the Mechanical Behavior of a β-Type Titanium Alloy Developed for Biomedical Applications

2012 ◽  
Vol 706-709 ◽  
pp. 135-142 ◽  
Author(s):  
Mitsuo Niinomi ◽  
Masaaki Nakai
Keyword(s):  
Tensile Strength ◽  
Titanium Alloy ◽  
Mechanical Behavior ◽  
Titanium Alloys ◽  
Biomedical Applications ◽  
The Other ◽  
Excess Oxygen ◽  
Ω Phase ◽  
Other Hand ◽  
Effect Of Oxygen

Oxygen enhances the strength of titanium alloys in general; however, excess oxygen can make titanium alloys brittle. On the other hand, oxygen enhances the precipitation of the α phase and suppresses the formation of the ω phase. Thus, using the optimal amount of oxygen is important to improve the mechanical properties of titanium alloys. The role of oxygen in titanium alloys is still not well understood. The effect of oxygen on the mechanical behavior of a β-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (referred to as TNTZ), which is used for biomedical applications, was investigated in this study. Oxygen was found to stabilize the ω phase in TNTZ. This behavior of oxygen is unusual considering the known behavior of oxygen in titanium alloys: oxygen is known to suppress the formation of the ω phase in titanium alloys. A small amount of oxygen increases the tensile strength but decreases the ductility of TNTZ. On the other hand, a large amount of oxygen, of around 0.7 mass%, increases both the tensile strength and the ductility of TNTZ. This phenomenon is unexpected.

EXPERIMENTAL AND NUMERICAL INVESTIGATIONS OF STOCHASTIC THICKNESS EFFECTS IN DISCONTINUOUS FIBER COMPOSITES

2021 ◽  
Author(s):  
SEUNGHYUN KO ◽  
TROY NAKAGAWA ◽  
ZHISONG CHEN ◽  
JAMES DAVEY ◽  
TALAL ABDULLAH ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Mechanical Behavior ◽  
Computational Models ◽  
Orientation Distribution ◽  
Fiber Composites ◽  
The Other ◽  
Numerical Investigations ◽  
Aspect Ratios ◽  
Other Hand ◽  
Discontinuous Fiber

Discontinuous fiber composites (DFCs) made of chopped prepreg tapes have recently drawn the attention of the aerospace and automobile industries thanks to their flexible manufacturing capability. Because of the discontinuity in a form of prepreg tapes, the fibers easily follow the mold contours while maintaining comparable stiffness and strength to continuous quasi-isotropic laminates. Furthermore, the high production rates and part complexities enabled by DFCs make them a competitive alternative to the use of metals in several applications. However, one of the current roadblocks for the use of DFCs is the lack of reliable analysis methods to predict their mechanical behavior, which depends on different parameters such as platelet sizes, aspect ratios, and spatial distribution. In this paper, we first experimentally investigated tensile elastic modulus and strength of unnotched coupons made of two different platelet aspect ratios (square and narrow) for varying coupon thicknesses. From the experiments, the square platelets showed significant thickness effects on both elastic modulus and strength. The narrow platelets also had significant thickness effects on strength but relatively constant modulus with varying thicknesses. In both modulus and strength, the narrow platelets had higher average values with larger deviations. Next, we computationally examined the relationship between the platelet distributions and the corresponding thickness effects. To get a thorough understanding of the effects of the platelet distribution on the mechanical behavior, the analysis was performed in two steps. In the first step, computational models were generated utilizing a uniform platelet distribution. In the second step, the models were generated leveraging platelet orientation tensors obtained from X-ray micro-computed tomography characterization. It was found that the assumption of a uniform orientation distribution condition was sufficient to capture the average modulus and strength with varying thicknesses for both platelet sizes. However, the associated Coefficient of Variation (CoV) of the results were significantly underpredicted, especially in the case of narrow platelets. On the other hand, numerical results using the orientation tensor obtained via micro-CT provided significantly improved predictions of the CoVs with varying thicknesses. These numerical investigations suggest that, for parts manufactured in conditions of limited platelet flow, the average mechanical performance can be accurately predicted by stochastic Finite Element models featuring a uniform platelet orientation distribution. On the other hand, the prediction of the CoV of moduli and strengths urges the use of an accurate representation of the real platelet morphology.

scholarly journals Removable friction dampers for low-damage steel beam-to-column joints

2021 ◽  
Author(s):  
Massimo Latour ◽  
Mario D'Aniello ◽  
Gianvittorio Rizzano ◽  
Vincenzo Piluso ◽  
Mariana Zimbru ◽  
...  
Keyword(s):  
Structural Damage ◽  
Vertical Direction ◽  
Experimental Tests ◽  
Steel Plates ◽  
Friction Dampers ◽  
Steel Moment Resisting Frames ◽  
First Case ◽  
Lower Beam ◽  
Moment Resisting ◽  
Design Requirements

Beam-to-column joints equipped with friction dampers are promising solutions to improve the performance of steel moment resisting frames due to the possibility to guarantee large dissipation capacity limiting the structural damage under severe seismic conditions. In this paper, the experimental tests and the numerical simulations of two types of joints are shown and discussed with the aim of developing pre-qualified configurations. The friction dampers are designed to be easily removable from both the lower beam flange and the column face by means of bolted connections. The devices are composed of a stack of steel plates conceived to assure symmetrical friction. The friction surface is set in vertical direction in first case and in horizontal direction in the second type. The experimental tests confirmed the effectiveness of both examined joints and the finite element analyses allowed characterizing their local response, thus providing additional insights to improve the design requirements.

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