Local Buckling Coefficient of Thin-Walled Pultruded FRP Compression Members

2007 ◽  
Vol 334-335 ◽  
pp. 377-380 ◽  
Author(s):  
Joo Hyung Joo ◽  
Soon Jong Yoon ◽  
Ju Kyung Park ◽  
Sun Kyu Cho
Keyword(s):  
Civil Engineering ◽  
Plate Theory ◽  
Low Cost ◽  
Local Buckling ◽  
Approximate Equation ◽  
Material Strength ◽  
Structural Members ◽  
Engineering Structures ◽  
Buckling Coefficient ◽  
Thin Walled

Recently there has been an increased demand in the use of FRP materials as load-bearing structural elements for the civil engineering applications, since FRP composite materials offer superior properties to conventional structural materials used in civil engineering structures. Among various production techniques, the pultrusion process has enabled the production of structural profiles with large cross sections at relatively low cost. Pultruded structural members are generally manufactured in the form of thin-walled member composed of plate elements and material properties can often be assumed as orthotropic. Due to the relatively low geometrical stiffness, often combined with low elastic modulus, the design of pultruded profiles is governed by the deflection or buckling rather than the material strength. In this paper, the elastic local buckling coefficient of the pultruded structural member having L-, T- and box-shape under the uniform in-plane compression was investigated and approximate equation to find the local buckling strength was proposed by using the classical orthotropic plate theory and energy method. The suggested equation can be used in the development of the design criteria and local buckling analysis of pultruded structural members.

On the Vibration of Layered Sandwich Elastic Plates

2008 ◽  
Author(s):  
Vincent O. S. Olunloyo ◽  
Charles A. Osheku
Keyword(s):  
Plate Theory ◽  
Impact Damage ◽  
Local Buckling ◽  
Recent Analysis ◽  
Sandwich Plates ◽  
Elastic Plates ◽  
Interface Pressure ◽  
Engineering Structures ◽  
Thin Plate Theory ◽  
Operational Methods

Sandwich elastic plates have found increasing applications in civil, aerospace, military and offshore industries to enhance superior resistance to fatigue crack propagation, impact damage, local buckling and are very effective for vibration damping and noise reduction. Such structural application has significantly led to reduction in vulnerability of warships to blasts, ballistics, bomb and fire attacks. In engineering structures, one of the effective ways of damping vibration and noise attenuation, is to exploit the occurrence of slip at the interface of structural laminates where such members are held together in a pressurised environment. Recent analysis and experimental investigation of vibration characteristics and damping properties of layered sandwich structures, are mostly limited to elastic beams. This paper is an attempt to extend such analytical investigations to layered sandwich plates. By employing contact mechanics and laminated thin plate theory, the generalised equation governing the vibration of two layered sandwich plates that are held together in pressurised environment is presented. In particular, by invoking operational methods for the case of linear interface pressure distribution, closed form analytical results for the system natural frequency and dynamic response under external excitation are reported for design analysis and applications.

Optical Measuring Technique for the Investigation of Built-Up Cold-Formed Steel Structural Members

2011 ◽  
Vol 473 ◽  
pp. 343-351 ◽  
Author(s):  
Iveta Georgieva ◽  
Luc Schueremans ◽  
Guido De Roeck ◽  
Lincy Pyl
Keyword(s):  
Local Buckling ◽  
Structural Members ◽  
Distortional Buckling ◽  
Residential Housing ◽  
3D Motion Analysis ◽  
Vertical Displacements ◽  
Global Buckling ◽  
Cold Formed Steel ◽  
Thin Walled ◽  
Displacement Transducers

The construction industry uses cold-formed steel (CFS) sheets in the form of galvanised thin-walled profiles and corrugated sheets. In the past decade, CFS profiles have been competing with their hot-rolled counterparts as primary structural members of industrial halls, office buildings and residential housing of up to 3-4 storeys. The spans and column heights achieved with CFS profiles are ever larger. Due to the large slenderness of these members, adequate strength and stability are necessary, as well as reliability in design. Thin-walled members go through buckling during all stages of their working life. Local buckling appears at loads sometimes much lower than the design load. Distortional buckling seriously reduces the member resistance. It interacts with warping and lateral-torsional buckling, being significant for these asymmetric open sections. To restrict these effects, builders employ double sections - usually two standard cold-formed shapes bolted together to form a built-up section. These sections have the advantages of symmetry, higher stability and strength. The design of built-up members involves many uncertainties - although the European standard includes guidelines on the prediction of local, distortional and global buckling, the partial integrity and interaction between the parts of the composed members is still not studied. To study the actual behaviour, built-up members are tested in bending. An optical device for 3D motion analysis measures the displacement of points of interest on the specimen. Two interacting cameras use parallax to obtain the position of an arbitrary number of reflective markers glued to the specimen. The device tracks the movement of the markers in a 3D coordinate system without any contact with the specimen. Standard displacement transducers measure vertical displacements to validate the results. The paper gives an appraisal of the applicability of the method, a summary of the difficulties faced and the outcome of the test campaign.

scholarly journals Vibration Monitoring of Civil Engineering Structures Using Contactless Vision-Based Low-Cost IATS Prototype

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 7952
Author(s):  
Rinaldo Paar ◽  
Ante Marendić ◽  
Ivan Jakopec ◽  
Igor Grgac
Keyword(s):  
Natural Frequencies ◽  
Civil Engineering ◽  
Low Cost ◽  
Deformation Monitoring ◽  
Vibration Monitoring ◽  
Monitoring Systems ◽  
Load Testing ◽  
Engineering Structures ◽  
Civil Engineering Structures

The role and importance of geodesists in the planning and building of civil engineering constructions are well known. However, the importance and benefits of collected data during maintenance in exploitation have arisen in the last thirty years due primarily to the development of Global Positioning Systems (GPS) and Global Navigation Satellite System (GNSS) instruments, sensors and systems, which can receive signals from multiple GPS systems. In the last fifteen years, the development of Terrestrial Laser Scanners (TLS) and Image-Assisted Total Stations (IATS) has enabled much wider integration of these types of geodetic instruments with their sensors into monitoring systems for the displacement and deformation monitoring of structures, as well as for regular structure inspections. While GNSS sensors have certain limitations regarding their accuracy, their suitability in monitoring systems, and the need for a clean horizon, IATS do not have these limitations. The latest development of Total Stations (TS) called IATS is a theodolite that consists of a Robotic Total Station (RTS) with integrated image sensors. Today, IATS can be used for structural and geo-monitoring, i.e., for the determination of static and dynamic displacements and deformations, as well as for the determination of civil engineering structures’ natural frequencies. In this way, IATS can provide essential information about the current condition of structures. However, like all instruments and sensors, they have their advantages and disadvantages. IATS’s biggest advantage is their high level of accuracy and precision and the fact that they do not need to be set up on the structure, while their biggest disadvantage is that they are expensive. In this paper, the developed low-cost IATS prototype, which consists of an RTS Leica TPS1201 instrument and GoPro Hero5 camera, is presented. At first, the IATS prototype was tested in the laboratory where simulated dynamic displacements were determined. After the experiment, the IATS prototype was used in the field for the purpose of static and dynamic load testing of the railway bridge Kloštar, after its reconstruction according to HRN ISO NORM U.M1.046—Testing of bridges by load test. In this article, the determination of bridge dynamic displacements and results of the computation of natural frequencies using FFT from the measurement data obtained by means of IATS are presented. During the load testing of the bridge, the frequencies were also determined by accelerometers, and these data were used as a reference for the assessment of IATS accuracy and suitability for dynamic testing. From the conducted measurements, we successfully determined natural bridge frequencies as they match the results gained by accelerometers.

Load-Carrying Capacity Estimation Methods for Cold-Formed Steel Lipped Channel Member Using Effective Width Method

2010 ◽  
Vol 163-167 ◽  
pp. 90-101 ◽  
Author(s):  
Xing You Yao ◽  
Yuan Qi Li ◽  
Zu Yan Shen
Keyword(s):  
Steel Structures ◽  
Channel Member ◽  
Effective Width ◽  
Structural Members ◽  
Distortional Buckling ◽  
Plate Buckling ◽  
Load Carrying ◽  
Cold Formed Steel ◽  
Buckling Coefficient ◽  
Thin Walled

Distortional buckling may occur for Cold-formed thin-walled steel lipped channel member except local buckling and overall buckling. The buckling of flange and lip are the important factor for the occurrence the distortional buckling. The different design codes have different design method for calculating plate buckling coefficient of flange and lip using the effective width method. So the effective width method in different codes are introduced and the load-carrying capacities of 100 lipped channel section compressive members collected from reference are computed using ‘Cold-formed steel structures (AS/NZS 4600:2005)’, ‘Supplementary rules for cold-formed members and sheeting(EN1993-1-3:2006)’, ‘North American specification for the design of cold-formed steel Structural Members(AISI-S100:2007)’, ‘Specification for the design of cold-formed steel structural members (AISI:1996)’ and ‘Technical code of cold-formed thin-walled steel structures’(GB50018-2002). The calculated results show that ‘Technical code of cold-formed thin-walled steel structures (GB50018-2002)’ and ‘Supplementary rules for cold-formed members and sheeting (EN1993-1-3:2006)’ are conservative and ‘Cold-formed steel structures (AS/NZS 4600:2005)’, ‘North American specification for the design of cold-formed steel Structural Members (AISI-S100:2007)’ and ‘Specification for the design of cold-formed steel structural members (AISI:1996)’ are unsafe. The elastic buckling stress of different lipped channel sections are predicted by finite strip program (CUFSM) and get the suggested calculation formula of plate buckling coefficient of flange according to regression Analysis. The calculated results using suggested plate buckling coefficient of flange are agree to test results.

ELASTIC BUCKLING OF THIN-WALLED CIRCULAR TUBES CONTAINING AN ELASTIC INFILL

2006 ◽  
Vol 06 (04) ◽  
pp. 457-474 ◽  
Author(s):  
M. A. BRADFORD ◽  
A. ROUFEGARINEJAD ◽  
Z. VRCELJ
Keyword(s):  
Axial Compression ◽  
A Priori ◽  
Local Buckling ◽  
Steel Tube ◽  
Transcendental Equation ◽  
Buckling Mode ◽  
Buckling Stress ◽  
Elastic Tubes ◽  
Thin Walled ◽  
Energy Formulation

Circular thin-walled elastic tubes under concentric axial loading usually fail by shell buckling, and in practical design procedures the buckling load can be determined by modifying the local buckling stress to account empirically for the imperfection sensitive response that is typical in Donnell shell theory. While the local buckling stress of a hollow thin-walled tube under concentric axial compression has a solution in closed form, that of a thin-walled circular tube with an elastic infill, which restrains the local buckling mode, has received far less attention. This paper addresses the local buckling of a tubular member subjected to axial compression, and formulates an energy-based technique for determining the local buckling stress as a function of the stiffness of the elastic infill by recourse to a transcendental equation. This simple energy formulation, with one degree of buckling freedom, shows that the elastic local buckling stress increases from 1 to [Formula: see text] times that of a hollow tube as the stiffness of the elastic infill increases from zero to infinity; the latter case being typical of that of a concrete-filled steel tube. The energy formulation is then recast into a multi-degree of freedom matrix stiffness format, in which the function for the buckling mode is a Fourier representation satisfying, a priori, the necessary kinematic condition that the buckling deformation vanishes at the point where it enters the elastic medium. The solution is shown to converge rapidly, and demonstrates that the simple transcendental formulation provides a sufficiently accurate representation of the buckling problem.

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