scholarly journals Pull-out Behaviour of Extended Hollobolts for Hollow Beam-Column Connections

2018 ◽  
Author(s):  
Mohd Fazaulnizam Bin Shamsudin ◽  
Walid Tizani
Keyword(s):  
Concrete Strength ◽  
Weight Ratio ◽  
High Strength ◽  
Element Model ◽  
Embedment Depth ◽  
Gusset Plates ◽  
Hollow Section ◽  
Hollow Beam ◽  
Pull Out ◽  
Joint Behaviour

The use of structural hollow sections (SHS) as columns in single-storey and multi-storey results in better compression strength, low surface area, architectural attractiveness and high strength to weight ratio. One major constraint when connecting to hollow sections is in accessing and tightening the bolt from the inside of the hollow section. To resolve this issue, full welding is usually applied. But this may suffer from high labour cost, and the potential of low quality welding due to workmanship and varied environmental conditions. Connecting using additional components, such as gusset plates and brackets, helps to ease this problem but lowers aesthetic appeal. To avoid the need to access to the inner face of the column section, new type of fasteners known as blind bolts were introduced. In this paper, experimental and numerical studies were conducted using a new anchored blind bolt known as the Extended HolloBolt (EHB), with the objective of using the component method for predicting joint behaviour within the tensile region. The behaviour of EHB in a group with different connection topologies and configurations was investigated using a total of 36 tests with one row of M16 Grade 8.8 and 10.9 bolts subjected to pull-out loading in tension. The experimental work covers a range of parameters such as bolt gauge, concrete strength, concrete type, bolt embedment depth and bolt class. A finite element model was implemented with good agreement between experimental and simulated load-deflection results, which have a maximum difference of 2.5%, shows that the model is suitable to be used for parametric studies or analytical work in further research on the EHB.

Bond behavior of high strength concrete under reversed pull-out cyclic loading

2002 ◽  
Vol 29 (2) ◽  
pp. 191-200 ◽  
Author(s):  
M Alavi-Fard ◽  
H Marzouk
Keyword(s):  
Cyclic Loading ◽  
Bond Strength ◽  
High Strength Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Displacement Curve ◽  
Bond Slip ◽  
Strength Concrete ◽  
Pull Out ◽  
Normal Strength

Structures located in seismic zones require significant ductility. It is necessary to examine the bond slip characteristics of high strength concrete under cyclic loading. The cyclic bond of high strength concrete is investigated under different parameters, including load history, confining reinforcement, bar diameter, concrete strength, and the rate of pull out. The bond strength, cracking, and deformation are highly dependent on the bond slip behavior between the rebar and the concrete under cyclic loading. The results of cyclic testing indicate that an increase in cyclic displacement will lead to more severe bond damage. The slope of the bond stress – displacement curve can describe the influence of the rate of loading on the bond strength in a cyclic test. Specimens with steel confinement sustained a greater number of cycles than the specimens without steel confinement. It has been found that the maximum bond strength increases with an increase in concrete strength. Cyclic loading does not affect the bond strength of high strength concrete as long as the cyclic slip is less than the maximum slip for monotonic loading. The behavior of high strength concrete under a cyclic load is slightly different from that of normal strength concrete.Key words: bond, high strength, cyclic loading, bar spacing, loading rate, failure mechanism.

scholarly journals Experimental Study of Friction Resistance between Steel and Concrete in Prefabricated Composite Beam with High-Strength Frictional Bolt

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Qi Guo ◽  
Qing-wei Chen ◽  
Ying Xing ◽  
Ya-ning Xu ◽  
Yi Zhu
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
Finite Element Model ◽  
Bearing Capacity ◽  
Concrete Strength ◽  
High Strength ◽  
Element Model ◽  
Construction Time ◽  
Friction Behavior ◽  
Friction Resistance

Prefabrication of composites beam reduces the construction time and makes them easily to be assembled, deconstructed, and partially repaired. The use of high-strength frictional bolt shear connectors can greatly enhance the sustainability of infrastructure. However, researches about the concrete-steel friction behavior are very limited. To provide a contribution to this area, 21 tests were conducted to measure the friction coefficient and slip stiffness with different concrete strength, steel strength, and surface treatment of steel. An effective finite element model was developed to investigate the ultimate bearing capacity and load-slip characteristics of bolt shear connection. The accuracy of the proposed finite element model is validated by the tests in this paper. The results demonstrate a positive correlation between concrete strength and friction coefficient and better performance of shot-blasted steel. It is also proved that high-strength frictional bolt has a 30% lower bearing capacity but better strength reserve and antiuplifting than the headed stud.

scholarly journals The Structural Diagnosis of Existing RC Buildings: The Role of Nondestructive Tests in the Case of Low Concrete Strength

2020 ◽  
Vol 5 (11) ◽  
pp. 100
Author(s):  
Silvia Santini ◽  
Angelo Forte ◽  
Lorena Sguerri
Keyword(s):  
Mechanical Properties ◽  
Concrete Strength ◽  
High Strength ◽  
Ultrasonic Pulse ◽  
Assessment Process ◽  
Structural Safety ◽  
Existing Structures ◽  
Nondestructive Tests ◽  
Compression Properties ◽  
Pull Out

In the structural safety assessment process of existing structures, knowledge of the mechanical properties of the materials is key. Different experimental activities carried out on materials extracted from existing reinforced concrete buildings show a high strength variability, especially concrete. In the past, the lack of standardized quality control for materials and workmanship caused nonuniform and homogeneous properties within the same structure. The most accurate and reliable experimental technique consists of performing direct tests on the materials, but these are considerably expensive and invasive. In this paper, alternative indirect methods that estimate material properties by correlating different physical measures were proved to reduce invasive inspections on existing buildings and infrastructures, especially in built heritage. A complete experimental activity concerning destructive and nondestructive tests was conducted on elements (four portions of a column and a beam portion) removed from an Italian school building built in 1940. Destructive and nondestructive methods were compared and appropriate correlation laws developed to predict the main mechanical properties of the studied material. Reliable correlations were identified considering the pull-out test, Sonic–Rebound (SonReb) combined method and ultrasonic pulse velocities (UPVs). The latter were mapped by tomography, which highlighted the compression properties of concrete in the different structural sections.

Compressive strengths of concrete-filled double-skin (circular hollow section outer and square hollow section inner) aluminium tubular sections

2019 ◽  
Vol 22 (11) ◽  
pp. 2418-2434 ◽  
Author(s):  
Feng Zhou ◽  
Ben Young
Keyword(s):  
Concrete Strength ◽  
Element Model ◽  
Numerical Results ◽  
Outer Skin ◽  
Hollow Section ◽  
Composite Columns ◽  
Double Skin ◽  
Stub Column ◽  
Circular Hollow Section ◽  
Stub Columns

Experimental and numerical investigations of concrete-filled double-skin aluminium stub column with a circular hollow section as the outer skin and a square hollow section as the inner skin are presented in this article. A test program was carried out to study the influences of aluminium tube geometric dimensions and concrete strength on structural performance and strength of composite columns. A series of composite columns was tested on outer circular hollow section tubes and inner square hollow section tubes; the spaces between them had been filled with concrete of different nominal cylinder strengths of 40, 70 and 100 MPa. The tubes were fabricated by extrusion using 6061T6 heat-treated aluminium alloy having a nominal 0.2% proof stress of 240 MPa. A non-linear finite element model was developed and verified against experimental results. The test and numerical results were compared with the design strengths to evaluate the applicability of the design rules in the American specifications for aluminium and concrete structures. In addition, the proposed design equations, developed by the authors for concrete-filled double-skin aluminium tubular stub columns with circular hollow section as both outer and inner skins, were used to calculate the design strengths and compared with the experimental and numerical results obtained in this study. The proposed design equations also predicted the ultimate strengths of the concrete-filled double-skin aluminium tubular stub columns accurately with circular hollow section as the outer skin and square hollow section as the inner skin.

scholarly journals Experimental Investigation of Fatigue Debonding Growth in FRP–Concrete Interface

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1459 ◽  
Author(s):  
Xinzhe Min ◽  
Jiwen Zhang ◽  
Chao Wang ◽  
Shoutan Song ◽  
Dong Yang
Keyword(s):  
Growth Rate ◽  
Weight Ratio ◽  
High Strength ◽  
Load Level ◽  
Experimental Results ◽  
Fatigue Load ◽  
Load Range ◽  
Pull Out ◽  
Reinforced Polymer ◽  
Externally Bonded

An externally bonded fiber reinforced polymer (FRP) plate (or sheet) is now widely used in strengthening bending members due to its outstanding properties, such as a high strength to weight ratio, easy operating, corrosion and fatigue resistance. However, the concrete member strengthened by this technology may have a problem with the adhesion between FRP and concrete. This kind of debonding failure can be broadly classified into two modes: (a) plate end debonding at or near the plate end, and (b) intermediate crack-induced debonding (intermediate crack-induced (IC) debonding) near the loading point. The IC debonding, unlike the plate end debonding, still needs a large amount of investigation work, especially for the interface under fatigue load. In this paper, ten single shear pull-out tests were carried out under a static or fatigue load. Different load ranges and load levels were considered, and the debonding growth process was carefully recorded. The experimental results indicate that the load range is one of the main parameters, which determines the debonding growth rate. Moreover, the load level can also play an important role when loaded with the same load range. Finally, a new prediction model of the fatigue debonding growth rate was proposed, and has an excellent agreement with the experimental results.

Stretch Formability Behaviour of Glass Fibre Reinforced Nanoclay on Fiber Metal Laminated Composites

2018 ◽  
Vol 10 (2) ◽  
Author(s):  
K. Logesh ◽  
V.K Bupesh Raja ◽  
C. Krishnaraj
Keyword(s):  
Ductile Fracture ◽  
Epoxy Resin ◽  
Glass Fibre ◽  
Weight Ratio ◽  
High Strength ◽  
Core Material ◽  
Fibre Metal Laminates ◽  
Sem Image ◽  
Pull Out ◽  
Fibre Metal

Innovations and research in material processing have brought forward new and improvised materials that are applied in body panels of automobiles, aircraft cabins and railway wagons. These materials are used widely is because of their good mechanical properties and their high strength to weight ratio. In this paper Fibre Metal Laminates (FMLs) were added with organo modified montmorillonite (MMT) commonly known as nanoclay along with epoxy resin. The homogeneous dispersion of nanoclay in epoxy resin is accomplished by a hand stirrer dispersion method in ethanol. The FML material was processed by hand layup method. In this study the aluminium alloy 5052-H32 was used as a skin material and glass fibre (woven roving) used as core material which is bounded by epoxy with 5 wt.% nano clay (closet 30B). The fabricated sandwich material was cut by using water jet machine as per IS standards for testing. The fabricated material subjected to erichsen cupping test and was observed under Scanning Electron Microscope (SEM). The results from SEM image analysis indicated that the FML had fibre pull out and surface cracks were obtained in the skin material. Progressive loading resulted in ductile fracture which is absorbed in the specimen. Fibres came across brittle failure and the skin through ductile fracture. Non-uniform distribution of reinforcement is observed in the material, SEM micrographs revealed fibre cracks which were oriented in line to the direction of crack growth on the skin material. This study shows that these fibre metal laminates can be safely applied in automotive field.

Validation of Macroscopic Forming Simulations of a Unidirectional Pre-Impregnated Material through Optical Measurements

2013 ◽  
Vol 554-557 ◽  
pp. 465-471 ◽  
Author(s):  
Alexane Margossian ◽  
François Dumont ◽  
Uwe Beier
Keyword(s):  
Finite Element ◽  
Carbon Fibre ◽  
Weight Ratio ◽  
High Strength ◽  
Element Model ◽  
Optical Measurements ◽  
Woven Fabric ◽  
Measuring System ◽  
Finite Element Software ◽  
Carbon Fibre Reinforced Plastic

Presenting interesting aspects such as a high strength-to-weight ratio, Carbon Fibre Reinforced Plastic components are frequently used in the aerospace industry. The forming step, which conforms the reinforcement to a specific geometry, is a sensitive phase of the manufacturing process. In order to detect the occurrence of defects prior to any trial, forming methods are often simulated via finite element software. The presented work will detail the simulation validation of a double curved helicopter frame forming out of a unidirectional carbon fibre pre-impregnated material (M21E, Hexcel®). The finite element model was based on an explicit approach at a macroscopic level and developed via the commercially available software Visual-Crash PAM (ESI®) [1]. The validation was carried out on six different preforms. Measurements of the top layers were performed by an enhanced version of a 4D measuring system, originally developed for non-woven fabric [2], able to make reproducible photographic and height measurements (Fig. 1). Experimental results were then compared to simulated ones. Due to material specificities, the photo quality reached for non-crimp fabrics could not be achieved [2]. After hardware and software modifications, measurements and analyses were eventually successfully completed. The validation of the simulation reached an accuracy of 1° to 3° depending on the geometrical features of the preform (Fig. 2).

Behavior of Steel Tube and Confined High Strength Concrete for Concrete-Filled RHS Tubes

2005 ◽  
Vol 8 (2) ◽  
pp. 101-116 ◽  
Author(s):  
Sumei Zhang ◽  
Lanhui Guo ◽  
Zaili Ye ◽  
Yuyin Wang
Keyword(s):  
High Strength Concrete ◽  
Concrete Strength ◽  
Compressive Load ◽  
High Strength ◽  
Steel Tube ◽  
Experimental Results ◽  
Stress Strain ◽  
Hollow Section ◽  
Strength Concrete ◽  
Nonlinear Stress

This paper presents an experimental study of the separated behavior of short ( L/H=3) high strength concrete-filled rectangular hollow section (RHS) tubes concentrically loaded in compression to failure. A total of 50 specimens were tested. Experimental results showed that the concrete strength influenced the failure pattern of the specimen. The height-to-breadth ratio of the rectangular tube (varying from 1.0 to 1.6) had no evident influence on the ultimate bearing capacity of the specimen. Then based on the experimental results, a numerical separation method was successfully used to separate the compressive load carried by the steel tube and the core concrete. The equivalent One-Dimensional nonlinear stress-strain models of the steel and the confined concrete were suggested, which can be used to determine the overall behavior of the high strength concrete-filled RHS tubes. The stress-strain models have been used to numerically analyze the behavior of high strength concrete-filled RHS tubes. The numerical results are compared with the experimental results and they agreed well with each other.

Surface Roughness Study of Milled Carbon Fiber Reinforced Polymer (CFRP) Composite Using 4 mm 2-Flute Titanium Aluminum Nitride (TiAlN) Coated Carbide End Mills

2014 ◽  
Vol 887-888 ◽  
pp. 1101-1106 ◽  
Author(s):  
Mohamed Konneh ◽  
Sudin Izman ◽  
Mirza Emmil Dzahi Padil ◽  
Rosniza Roszat
Keyword(s):  
Surface Roughness ◽  
Weight Ratio ◽  
High Strength ◽  
Milling Process ◽  
Machining Parameters ◽  
Inherent Anisotropy ◽  
Pull Out ◽  
Cfrp Composite ◽  
End Mills ◽  
Coated Carbide

As the goal for aircraft weight reduction and low fuel consumption becomes a dire concern in aerospace industries, there is driving desire for the increasing use of advanced exotic materials such as composites, titanium and Inconels in the aerospace industry because of their high strength to weight ratio. Nevertheless the inherent anisotropy, inhomogeneous properties of CFRP and low bonding strength within the laminates make machining of these composite materials results in several undesirable effects such as delamination, micro-cracking, burr, fiber pull out and breakage. This paper discusses an experimental investigation into the influence of machining parameters on surface roughness when milling CFRP using 4 mm-diameter 2-fluted carbide end-mill coated with Titanium Aluminium Nitride (TiAlN). Relationship between the machining variables and the output variables is established and a mathematical model is predicted for the surface roughness produced during the milling process for the machining conditions investigated.

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