Flexural stiffness reduction for stainless steel SHS and RHS members prone to local buckling

2020 ◽  
Vol 155 ◽  
pp. 106939
Author(s):  
Yanfei Shen ◽  
Rolando Chacón
Keyword(s):  
Stainless Steel ◽  
Local Buckling ◽  
Flexural Stiffness ◽  
Stiffness Reduction

scholarly journals Low-rise structures in reinforced concrete: approximation of material nonlinearity for global stability analysis

2018 ◽  
Vol 11 (1) ◽  
pp. 1-25
Author(s):  
L. M. MOREIRA ◽  
C. H. MARTINS
Keyword(s):  
Global Stability ◽  
Iterative Process ◽  
Global Analysis ◽  
Second Order ◽  
Material Nonlinearity ◽  
Flexural Stiffness ◽  
Analysis Model ◽  
Structural Element ◽  
Global Stability Analysis ◽  
Stiffness Reduction

Abstract In the analysis of the second-order global effects, the material nonlinearity (NLF) can be considered in an approximate way, defining for the set of each structural element a mean flexural stiffness. However, there is less research concerning low-rise buildings in the analysis of global stability in contrast to high buildings, because these have a greater sensitivity to this phenomenon and they are more studied. In this way, the paper objective is to determine the flexural stiffness values, of beams and columns, for buildings with less than four floors, to approximate consideration of the NLF in the global analysis. The idealized examples to buildings with 1, 2 and 3 floors, being simulated through the software CAD/TQS and an analysis model based in an iterative process. The simulations results defined the stiffness values of the set of beams and columns in each example, followed by a statistical analysis to define general values of application in the buildings. Finally, a proposal is suggested of stiffness reduction coefficients for beams and columns to be adopted in the approximation the NLF (EIsec = αv/p ∙ Eci Ic), as follows: buildings with 1 floor (αv = 0,17 and αp = 0,66), buildings with 2 floors (αv = 0,15 and αv = 0,71) and buildings with 3 floors (αv = 0,14 and αv = 0,72). The results obtained can be used for the analysis of low-rise structures to consider the second order global effects with more safely.

Mechanical Organization of Cantileverlike Sessile Organisms: Sea Anemones

1977 ◽  
Vol 69 (1) ◽  
pp. 127-142
Author(s):  
M.A. R. KOEHL
Keyword(s):  
Elastic Modulus ◽  
Body Wall ◽  
Local Buckling ◽  
Beam Theory ◽  
Extension Rate ◽  
Flexural Stiffness ◽  
Sea Anemones ◽  
Order Of Magnitude ◽  
Anthopleura Xanthogrammica ◽  
Sessile Organisms

Engineering beam theory has been used to analyse the ways in which body shape and elastic modulus of two species of sea anemones affect their mechanical responses to flow. 1.Anthopleura xanthogrammica is exposed to wave action, but because it is short, wide, and thick-walled, maximum tensile stresses in its body walls due to flow forces are an order of magnitude lower than those in the tall, slim, thin-walled, calm-water sea anemone Metridium senile.2. The elastic modulus of M. senile body wall is more dependent on extension rate than is that of A. xanthogrammica. Because the extension rate of M. senile body wall in tidal currents is higher than that of A. xanthogrammica in wave surge, the moduli of walls from these species when exposed to such flow conditions are similar, between 0.1 and 0.3 MN.m−2.3. The flexural stiffness of M. senile is lowest in the upper column where the anemones bend in currents: this orients their filter-feeding oral discs normal to the currents. The flexural stiffness of A. xanthogrammica is one to two orders of magnitude higher than that of M. senile; A. xanthogrammica remain upright in wave surge and feed on mussels that fall on their oral discs.4. The deflexions of these anemones predicted using beam theory are consistent with those observed in nature.5. The critical stress to produce local buckling is an order of magnitude lower for M. senile than for A. xanthogrammica.6. Several general principles of the organization of cantilever-like sessile organisms are revealed by this study of sea anemones.

Enhancing Broadband Vibration Energy Suppression Using Local Buckling Modes in Constrained Metamaterials

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Ryan L. Harne ◽  
Daniel C. Urbanek
Keyword(s):  
Vibration Suppression ◽  
Local Buckling ◽  
Engineering Systems ◽  
Buckling Modes ◽  
Dynamic Mass ◽  
Stiffness Reduction ◽  
Elastomeric Dampers ◽  
Practical Engineering ◽  
Post Buckling ◽  
Relative Change

Studies on dissipative metamaterials have uncovered means to suppress vibration and wave energy via resonant and bandgap phenomena through such engineered media, while global post-buckling of the infinitely periodic architectures is shown to tailor the attenuation properties and potentially magnify the effective damping effects. Yet, despite the promise suggested, the practical aspects of deploying metamaterials necessitates a focus on finite, periodic architectures, and the potential to therefore only trigger local buckling features when subjected to constraints. In addition, it is likely that metamaterials may be employed as devices within existing engineering systems, so as to motivate investigation on the usefulness of metamaterials when embedded within excited distributed or multidimensional structures. To illuminate these issues, this research undertakes complementary computational and experimental efforts. An elastomeric metamaterial, ideal for embedding into a practical engineering structure for vibration control, is introduced and studied for its relative change in broadband damping ability as constraint characteristics are modified. It is found that triggering a greater number of local buckling phenomena provides a valuable balance between stiffness reduction, corresponding to effective damping magnification, and demand for dynamic mass that may otherwise be diminished in globally post-buckled metamaterials. The concept of weakly constrained metamaterials is also shown to be uniformly more effective at broadband vibration suppression of the structure than solid elastomeric dampers of the same dimensions.

Direct Strength Method for Stainless Steel Lipped Channel Columns Undergoing Local Buckling

2020 ◽  
Vol 20 (6) ◽  
pp. 1822-1830
Author(s):  
Meihe Chen ◽  
Shenggang Fan ◽  
Chenxu Li ◽  
Shaoru Zeng
Keyword(s):  
Stainless Steel ◽  
Local Buckling ◽  
Direct Strength Method

Cell Network-Based Formulas for Fast Determination of Flexural Stiffness Reduction of U-Shaped Core Shear Walls

2018 ◽  
Vol 34 (2) ◽  
pp. 867-891
Author(s):  
Yicheng Yang ◽  
Sai Yemmaleni ◽  
Ikkyun Song ◽  
In Ho Cho
Keyword(s):  
Shear Walls ◽  
Shear Wall ◽  
Flexural Stiffness ◽  
Finite Element Analyses ◽  
Efficient Tool ◽  
Fast Determination ◽  
Cell Network ◽  
Stiffness Reduction ◽  
Unit Cells

Reinforced concrete (RC) core shear wall is one of the most widely used earthquake-resisting systems. Degradation of a core wall's flexural stiffness is vital for understanding the natural frequency shift of the damaged building. But it is hard to capture, often necessitating complex finite element analyses (FEAs). This study seeks to provide an efficient tool to quickly determine the remaining flexural stiffness of U-shaped core walls. Importantly, the tool is designed to require only the easy-to-collect observational damage information. Of primary novelty is a network of microscopic unit cells, each consisting of nonlinear concrete and steel springs along with a compression-only gap. Validations with three U-shaped walls tested under complex and multidirectional loading paths show that the proposed formulas appear promising in quickly determining the trend of degrading flexural stiffness compared with a high-precision multiscale FEA program. All the formulas written in Matlab codes are made publicly available. Using the portable formulas running on a laptop, practicing engineers and researchers will be able to swiftly diagnose core U-shaped walls after quick on-site or laboratory observations.

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