Experimental cyclic loading of concentric HSS braces

2011 ◽  
Vol 38 (1) ◽  
pp. 110-123 ◽  
Author(s):  
Madhar Haddad ◽  
Tom Brown ◽  
Nigel Shrive
Keyword(s):  
Energy Dissipation ◽  
Material Properties ◽  
Slenderness Ratio ◽  
Plate Thickness ◽  
Earthquake Ground Motion ◽  
Braced Frames ◽  
Gusset Plate ◽  
Plate Size ◽  
Tension And Compression ◽  
Hysteresis Behaviour

During earthquake ground motion, diagonal braces in braced frames are subject to a series of cyclic loadings, alternately tension and compression. The brace can buckle and deform plastically, dissipating energy with damage accumulating in the steel. Eventually a crack may form and the brace fractures. To optimize energy dissipation, the effects of brace and gusset plate dimensions (thickness and length of the gusset plate, size of the brace, length of the brace), and material properties, on brace behaviour, need to be understood. Ten concentric bracing members, designed according to the weak brace – strong gusset concept, were tested. The objective was to investigate the effects of displacement history, brace effective slenderness ratio, and brace width/thickness ratio, on the hysteresis behaviour of bracing members. Displacement history was found to affect energy dissipation and fracture life. The effects of increasing the gusset plate thickness on the energy dissipation and the fracture life is not the same as reducing the effective slenderness ratio of the bracing member resulted from reducing the length of the HSS. New fracture life and energy life equations are proposed.

Critical Plate Thickness for Energy Dissipation During Sphere–Plate Elastoplastic Impact Involving Flexural Vibrations

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Deepak Patil ◽  
C. Fred Higgs
Keyword(s):  
Energy Dissipation ◽  
Thin Plate ◽  
Material Properties ◽  
Input Parameter ◽  
Plate Thickness ◽  
Practical Importance ◽  
Sphere Diameter ◽  
Impact Parameters ◽  
Flexural Vibrations ◽  
The Impact

Solid processing storage and conveying units (e.g., hoppers, silos, tumblers, etc.) often involve the collision of granular media with relatively thin walls. Therefore, the impact of a sphere with a thin plate is a problem with both fundamental and practical importance. In the present work, the normal elastoplastic impact between a sphere and a thin plate is analyzed using an explicit finite element method (FEM). The impact involves plastic deformation and flexural vibrations, which when combined results in significant energy dissipation. One way to quantify the energy dissipation is to employ the coefficient of restitution (COR), which is also a key input parameter needed in various granular flow models. The results were validated against the available experimental data. It is observed that, in addition to material properties and impact parameters, the energy dissipation is strongly dependent on the ratio of plate thickness to sphere diameter. A comprehensive parametric study is conducted to evaluate the effect of material properties, geometry, and impact parameters on the energy dissipation. For the impact velocities commonly observed in granular systems (V = 5 m/s or less), it was determined that the energy lost to flexural vibrations can be neglected if the plate thickness is more than twice the sphere diameter, i.e., tcr > 2d. In this scenario, the mode of energy dissipated is primarily due to the plasticity effects.

Behaviour of square hollow structural steel braces with end connections under reversed cyclic axial loading

2003 ◽  
Vol 30 (4) ◽  
pp. 745-753 ◽  
Author(s):  
Brad Shaback ◽  
Tom Brown
Keyword(s):  
Energy Dissipation ◽  
Structural Steel ◽  
Slenderness Ratio ◽  
Axial Loading ◽  
Geometrical Model ◽  
Thickness Ratio ◽  
Gusset Plates ◽  
Gusset Plate ◽  
Hysteretic Behaviour ◽  
Specific Loading

The hysteretic behaviour of nine square hollow structural steel (HSS) sections with gusset plate end con nections subject to inelastic cyclic loading has been examined by an experimental investigation. Brace slenderness ratio, width to thickness ratio, and to a lesser extent, the end connection were identified as the key parameters in the tests. It was shown that the effective slenderness ratio is the most important parameter governing the hysteretic behaviour. The out-of-plane deflection of the brace can be accurately calculated using a simplified geometrical model or a model calibrated against the test results. Reduced compressive capacity as specified by the current Canadian Standards Asso ciation (CSA) standard was nonconservative for the specific loading sequence employed in this series of tests. Quantification of the energy dissipation proved that the gusset plates account for a small percentage of the total energy dissipated. The experimental fracture life of the specimens proved to be most affected by the width to thickness ratio and the effective slenderness ratio. An empirical equation is proposed to more accurately determine the theoretical fracture life of an HSS brace.Key words: brace, hysteresis, steel, hollow structural section, cyclic, end connection, fracture, energy dissipation, compressive capacity, effective slenderness ratio.

Analysis on Bearing Capacity of Double Back-to-Back Cold-Formed Thin-Walled C Steel Composite Column with Gusset Plate

2013 ◽  
Vol 351-352 ◽  
pp. 821-824
Author(s):  
Ming Chen ◽  
Wen Wen Lu ◽  
Kai Liu
Keyword(s):  
Bearing Capacity ◽  
Failure Modes ◽  
Slenderness Ratio ◽  
Plate Thickness ◽  
Correction Coefficient ◽  
Element Analysis ◽  
Gusset Plate ◽  
Composite Column ◽  
Plate Spacing ◽  
Thin Walled

According to the composite column of double back to back cold-formed thin-walled C steel connected with gusset plate, the experiment and finite element analysis were carried out to study the stability bearing capacity and failure modes of columns under eccentric loading. The factors such as slenderness ratio, eccentricity, gusset plate thickness and spacing were discussed, which produced the impacts to bearing capacity, and the relationship between stiffness and axial load. The results revealed that the failure modes belonged to the in-plane-flexural buckling and local-buckling of the pressurized flanges and webs of the columns. Slenderness ratio, eccentricity and gusset plate spacing are the major factors that affected the mechanical behavior, while the gusset plate thickness has no obvious impact. In the end, compared with the calculation of the bearing capacity of the cold-formed thin-walled column and GB50018-2002, some suggestions based on this composite column calculation were put forward, and the correction coefficient of bearing capacity of the composite columns were given.

Probabilistic Oblique Impact Analysis of Functionally Graded Plates – A Multivariate Adaptive Regression Splines Approach

2021 ◽  
Author(s):  
P. K. Karsh ◽  
Bindi Thakkar ◽  
R. R. Kumar ◽  
Vaishali ◽  
Sudip Dey
Keyword(s):  
Material Properties ◽  
Mass Density ◽  
Plate Thickness ◽  
Functionally Graded ◽  
Multivariate Adaptive Regression Splines ◽  
Low Velocity Impact ◽  
Fe Model ◽  
Low Velocity ◽  
Velocity Impact ◽  
Mars Model

Purpose: To investigate the probabilistic low-velocity impact of functionally graded (FG) plate using the MARS model, considering uncertain system parameters. Design/methodology/application: The distribution of various material properties throughout FG plate thickness is calculated using power law. For finite element (FE) formulation, isoparametric elements with eight nodes are considered, each component has five degrees of freedom. The combined effect of variability in material properties such as elastic modulus, modulus of rigidity, Poisson’s ratio, and mass density are considered. The surrogate model is validated with the FE model represented by the scatter plot and the probability density function (PDF) plot based on Monte Carlo simulation (MCS). Findings: The outcome of the degree of stochasticity, impact angle, impactor’s velocity, impactor’s mass density, and point of impact on the maximum value of contact force (CFmax ), plate deformation (PDmax), and impactor deformation (IDmax ) are determined. A convergence study is also performed to determine the optimal number of the constructed MARS model’s sample size. Originality/value: The results illustrate the significant effects of uncertain input parameters on FGM plates’ low-velocity impact responses by employing a surrogate-based MARS model.

The Baffle Blocks Effects of Pressure Characteristics on USBR III Basin Floor

2012 ◽  
Vol 212-213 ◽  
pp. 821-825
Author(s):  
Keyvan Nasiri ◽  
Mohammad Reza Kavianpour ◽  
Siavash Haghighi
Keyword(s):  
Energy Dissipation ◽  
Hydraulic Jump ◽  
Pressure Fluctuations ◽  
Power Spectra ◽  
Low Frequency ◽  
Dominant Frequency ◽  
Energy Dissipation Rate ◽  
Tension And Compression ◽  
Basin Floor ◽  
Sequent Depth

The principle of energy dissipation in stilling basin is based on hydraulic jump formation. Due to the inherent fluctuating characteristic of the hydraulic jump, basin floor is subjected to variations of pressure, resulting in unstableness due to uplift forces. To increase the efficiency of the stilling basins and improve the energy dissipation rate, one or two rows of baffle blocks are applied on the basin floor. Causing a forced hydraulic jump, tension and compression forces are exerted by pressure fluctuations of rotating roller zone of hydraulic jump. In this investigation, to observe the impacts of baffle blocks on pressure fluctuations on basin floor, a standard USBR basin model type III was constructed, and then a second row of blocks was added to the basin. A set of pressure tubes was fixed along the axis of the basin to measure the static and dynamic pressures on basin floor. The results were expressed in dimensionless parameters including C-p, C+p, C’p, Cp. Also, power spectra of pressure fluctuations were calculated. The results show a decreasing trend in root mean square of pressure fluctuations as distancing from toe of jump along the basin with and without baffle blocks. Also, mean pressure increases when water jet strokes the basin then decreases under roller zone of jump and increases again after sequent depth. The spectral analysis indicates that the dominant frequency is between 10 rad/s and 35 rad/s and pressure fluctuations have low frequency characteristics.

Damage and Crack Analysis for Reinforced Concrete Energy Dissipation Braced Frame (EDBF) under Low Cyclic Loads

2006 ◽  
Vol 324-325 ◽  
pp. 611-614
Author(s):  
Mei Ling Xiao ◽  
Liao Yuan Ye ◽  
Sheng Miao ◽  
Ben Yu Liu
Keyword(s):  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Ground Motion ◽  
Damage Variable ◽  
Dissipated Energy ◽  
Earthquake Ground Motion ◽  
Displacement Curve ◽  
Cyclic Loads ◽  
Braced Frame ◽  
Factor C

Application of Miner criterion, cumulate damage variable was estimated based on pseudo-static experiment study for reinforced concrete energy dissipation braced frame (EDBF) under low cyclic loads, accordingly, the constitutive relations about damage was established; the linear hook law turned into non-linear stress-strain relations; the dissipated-energy factor c β was determined based on following factors: the cumulate damage variable, hysteretic energy determined by load-displacement curve, maximum deformation and yield force of EDBF; it supplied a quantitative basis of dissipated-energy for EDBF; There were two reasons in energy dissipation for EDBF: one was energy dissipation equipment acting, the other was concrete damaged and cracked or low cycle fatigue failure in this structure, and the latter part of energy was associated with amounts of cracks and crack size; then the forced mechanism of EDBF was analyzed, and the reason caused cracks and crack type of EDBF columns, beam and braces were explained based on forced mechanism: the columns, beam and braces of EDBF were compressed or tensed under low cyclic loads, so most of cracks of columns, beam and braces belonged to mode I cracksThis study supplied a method for estimating energy of EDBF under earthquake ground motion, and the results showed: columns in EDBF are easily damaged under earthquake ground motion, so the structural elements must be designed strong column, weak beam and weak brace.

scholarly journals More than a safety line: jump-stabilizing silk of salticids

2013 ◽  
Vol 10 (87) ◽  
pp. 20130572 ◽  
Author(s):  
Yung-Kang Chen ◽  
Chen-Pan Liao ◽  
Feng-Yueh Tsai ◽  
Kai-Jung Chi
Keyword(s):  
Energy Dissipation ◽  
Dynamic Stability ◽  
Material Properties ◽  
High Speed ◽  
Prey Capture ◽  
Flapping Wings ◽  
Aerodynamic Forces ◽  
Physiological Control ◽  
Dragline Silk ◽  
Kinematic Data

Salticids are diurnal hunters known for acute vision, remarkable predatory strategies and jumping ability. Like other jumpers, they strive for stability and smooth landings. Instead of using inertia from swinging appendages or aerodynamic forces by flapping wings as in other organisms, we show that salticids use a different mechanism for in-air stability by using dragline silk, which was previously believed to function solely as a safety line. Analyses from high-speed images of jumps by the salticid Hasarius adansoni demonstrate that despite being subject to rearward pitch at take-off, spiders with dragline silk can change body orientation in the air. Instantaneous drag and silk forces calculated from kinematic data further suggest a comparable contribution to deceleration and energy dissipation, and reveal that adjustments by the spider to the silk force can reverse its body pitch for a predictable and optimal landing. Without silk, upright-landing spiders would slip or even tumble, deferring completion of landing. Thus, for salticids, dragline silk is critical for dynamic stability and prey-capture efficiency. The dynamic functioning of dragline silk revealed in this study can advance the understanding of silk's physiological control over material properties and its significance to spider ecology and evolution, and also provide inspiration for future manoeuvrable robot designs.

Optimal Elastic Design of CFCs

2011 ◽  
Vol 488-489 ◽  
pp. 295-298 ◽  
Author(s):  
Galyna Stasiuk ◽  
Romana Piat ◽  
Yuriy Sinchuk
Keyword(s):  
Elastic Properties ◽  
Material Properties ◽  
Bulk Material ◽  
Carbon Composite ◽  
Bending Test ◽  
Three Point Bending ◽  
Design Variables ◽  
Tension And Compression ◽  
Elastic Design ◽  
Analytical Homogenization

The aim of the proposed studies is the development of the carbon/carbon composite with prescribed elastic properties. To achieve this, a microstructure optimisation problem for estimation of the microstructure with prescribed stiffness is formulated. The design variables of the posed problem are the local fibers distribution and porosity. The volume fractions of the fibers and pores in the whole microstructure are fixed. Material properties of the local microstructure of the composite are calculated using virtual models. Semi-analytical homogenization procedures were used for the development of these models. Modeling results are compared with elastic properties obtained experimentally by tension and compression test and ultrasonic studies of the bulk material. Approach to design microstructure for three point bending test is proposed.

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