Model studies of the elastic buckling of a stiffened plate

1976 ◽  
Vol 11 (3) ◽  
pp. 137-143 ◽  
Author(s):  
J D Tulk ◽  
A C Walker
Keyword(s):  
Strain Range ◽  
Scale Model ◽  
Small Scale ◽  
Elastic Buckling ◽  
Engineering Structures ◽  
Model Studies ◽  
Plate Elements ◽  
Scale Models ◽  
Load Carrying ◽  
Post Buckling

The paper reports on an experimental investigation of the elastic buckling behaviour of a small-scale model of a stiffened plane. The model was made from epoxy resin to allow large buckle deflections within the elastic strain range. These tests are part of a programme aimed at proving the feasibility of using small-scale models to elucidate the behaviour of large stiffened plates such as are used in marine or civil engineering structures. It is shown for the geometry examined here that, although the component stringer and plate elements of the panel would individually exhibit stable post-buckling, together they interact to give unstable behaviour. The effects of imperfections are systematically studied and it is shown that the load-carrying capacity of such a structural configuration is sensitive to initial geometric deformations. A simple mathematical analysis is developed which indicates the parameters governing the physical problem and which could form the basis for future rational studies of the level of imperfections at which sensitivity may be considered slight.

scholarly journals Small Scale Experiments to Assess the Bearing Capacity of Footings on the Sloped Surface

Eng ◽  
2020 ◽  
Vol 1 (2) ◽  
pp. 240-248
Author(s):  
Mohammad Nurul Islam
Keyword(s):  
Bearing Capacity ◽  
Carrying Capacity ◽  
Maximum Load ◽  
Scale Model ◽  
Small Scale ◽  
Load Carrying Capacity ◽  
Engineering Structures ◽  
Load Carrying ◽  
Limiting Condition ◽  
The Impact

Construction of civil engineering structures on or next to a slope requires special attention to meet the bearing capacity requirements of soils. In this paper, to address such a challenge, we present laboratory-scale model tests to investigate the effect of footing shape on the sloped surface. The model comprised of a well stiffened mild steel box with three sides fixed and one side open. We considered both with and without reinforcement to assess the effectiveness of reinforcement on the sloped surface. Also, we used three types of footing (i.e., square, rectangular, and circular) to measure the footing shape effects. We considered three different slope angles to evaluate the impact of the sloped face corresponding to the applied load and the reinforcement application. We obtained that the maximum load carrying capacity in the square footing was higher than the rectangular and the circular footing for both the reinforced and the unreinforced soil. With the increase of geo-reinforcement in all three footing shapes and three sloped angles, the load carrying capacity increased. We also noticed a limiting condition in geo-reinforcement placement effectiveness. And we found that with the increase of slope, the load bearing capacity decreased. For a steep slope, the geo-reinforcement placement and the footing shape selection is crucial in achieving the external load sustainability, which we addressed herein.

scholarly journals Model studies on plate girders

1983 ◽  
Vol 18 (2) ◽  
pp. 111-117 ◽  
Author(s):  
R Narayanan ◽  
D Adorisio
Keyword(s):  
Shear Loading ◽  
Shear Capacity ◽  
Small Scale ◽  
Structural Behaviour ◽  
Plate Girders ◽  
Model Studies ◽  
Scale Models ◽  
Shear Buckling ◽  
Post Buckling ◽  
Ultimate Shear Capacity

Tests on eighteen small scale models which simulate the elastic and post-buckling behaviour of plate girders when subjected to shear loading are reported and discussed. The models were fabricated of steel and Araldite; the major aim was to assess whether small scale models can be employed to study shear buckling problems. A secondary object was to examine whether araldite could be used for predicting the structural behaviour and ultimate loads of plate girders. The strength and post-buckling characteristics exhibited by steel models were found to be similar to those observed by earlier investigators on full scale girders. The test results of steel models have been compared with the theoretical predictions obtained by using some ten design methods developed in different countries. Most of these methods are shown to give conservative but satisfactory predictions of the ultimate shear capacity of the model steel girders. Tests on Araldite models demonstrated that post-buckling behaviour can be observed visually on account of the large elastic deformations which the material is capable of, before collapse. However, they were found to be unsuitable for the prediction of the ultimate shear capacity. As Araldite is brittle, collapse would occur prematurely by sudden fracture before the full development of the tension field.

scholarly journals Roughness Lengths for Momentum and Heat Derived from Outdoor Urban Scale Models

2007 ◽  
Vol 46 (7) ◽  
pp. 1067-1079 ◽  
Author(s):  
M. Kanda ◽  
M. Kanega ◽  
T. Kawai ◽  
R. Moriwaki ◽  
H. Sugawara
Keyword(s):  
Wind Direction ◽  
Roughness Length ◽  
Scale Dependence ◽  
Scale Model ◽  
Small Scale ◽  
Physical Scale ◽  
Scale Models ◽  
Roughness Lengths ◽  
Urban Sites ◽  
Obstacle Height

Abstract Urban climate experimental results from the Comprehensive Outdoor Scale Model (COSMO) were used to estimate roughness lengths for momentum and heat. Two different physical scale models were used to investigate the scale dependence of the roughness lengths; the large scale model included an aligned array of 1.5-m concrete cubes, and the small scale model had a geometrically similar array of 0.15-m concrete cubes. Only turbulent data from the unstable boundary layers were considered. The roughness length for momentum relative to the obstacle height was dependent on wind direction, but the scale dependence was not evident. Estimated values agreed well with a conventional morphometric relationship. The logarithm of the roughness length for heat relative to the obstacle height depended on the scale but was insensitive to wind direction. COSMO data were used successfully to regress a theoretical relationship between κB−1, the logarithmic ratio of roughness length for momentum to heat, and Re*, the roughness Reynolds number. Values of κB−1 associated with Re* for three different urban sites from previous field experiments were intercompared. A surprising finding was that, even though surface geometry differed from site to site, the regressed function agreed with data from the three urban sites as well as with the COSMO data. Field data showed that κB−1 values decreased as the areal fraction of vegetation increased. The observed dependency of the bulk transfer coefficient on atmospheric stability in the COSMO data could be reproduced using the regressed function of Re* and κB−1, together with a Monin–Obukhov similarity framework.

scholarly journals Strengthening of steel member using unbonded CFRP laminates

2020 ◽  
Vol 156 ◽  
pp. 05025
Author(s):  
Fengky Satria Yoresta ◽  
Ryotaro Maruta ◽  
Genki Mieda ◽  
Yukihiro Matsumoto
Keyword(s):  
Steel Structures ◽  
Small Scale ◽  
Great Success ◽  
Adhesively Bonded ◽  
Engineering Structures ◽  
Rc Structures ◽  
Cfrp Laminates ◽  
Cfrp Composites ◽  
Steel Members ◽  
Load Carrying

Excellent mechanical and physical properties make carbon fiber reinforced polymer (CFRP) the best options for repair, retrofit, and rehabilitation of civil engineering structures. A great success on application of this material in reinforced concrete (RC) structures has attracted much attention from many researchers to develop it in combination with steel. The number of studies on the use of CFRP composites for strengthening steel structures has still been limited and needs to be more explored. To date, the research in this field has mainly focused on CFRP strengthening with adhesively-bonded technique. This paper reports an experimental study to investigate the performance of slender axial compression steel members partially strengthened with unbonded CFRP composites. The requirements for stiffener to prevent buckling occurred in stiffening region are derived from structural equilibrium conditions. Vacuum-assisted Resin Transfer Molding (VaRTM) method is adopted to form CFRP laminates in the strengthened specimens. Totally eight small scale specimens are tested, and it is clear from the test that improvement in load-carrying capacity can be achieved by using CFRP.

Local Buckling of Outstands in Stiffened Plates

1976 ◽  
Vol 27 (4) ◽  
pp. 277-291 ◽  
Author(s):  
W C Fok ◽  
J Rhodes ◽  
A C Walker
Keyword(s):  
Local Buckling ◽  
Strain Range ◽  
Maximum Load ◽  
Simple Expression ◽  
Stiffened Plates ◽  
Elastic Buckling ◽  
Analytical Prediction ◽  
Imperfection Sensitivity ◽  
Post Buckling ◽  
Overall Buckling

SummaryThis paper reports on an investigation of the effect of local elastic buckling of stiffener outstands on the overall behaviour of stiffened plates. A simplified mathematical model has been developed, based on the post-buckling analysis of the stiffener, and gives a simple expression which indicates that, for the plate geometry investigated, the maximum load carried varies asymptotically between the local critical load of the stiffener and a reduced Euler load. Also, there is a marked imperfection sensitivity arising from the interaction of the local and overall buckling modes. Experiments were carried out to confirm the analytical prediction for the elastic buckling behaviour of the stiffened plates. The models were constructed of Araldite, to allow large deformation within the elastic strain range. Experimental results showed very good agreement with the theory.

scholarly journals Effect of Turf Roof Slabs on Indoor Thermal Performance in Tropical Climates: A Life Cycle Cost Approach

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
R. U. Halwatura
Keyword(s):  
Life Cycle ◽  
Life Cycle Cost ◽  
Air Conditioning ◽  
Green Roof ◽  
Green Roofs ◽  
Scale Model ◽  
Small Scale ◽  
Indoor Temperature ◽  
Scale Models ◽  
Different Types

Urbanization related to population growth is one of the burning issues that the world is facing today. Parallel to this, there is visible evidence of a possible energy crisis in the near future. Thus, scientists have paid attention to sustainable development methods, and in the field of building construction also, several innovations have been proposed. For example, green roof concept is one of such which is considered a viable method mainly to reduce urban heat island effect, to regain lost land spaces in cities, and to increase aesthetics in cities. The present study was aimed at investigating the impact of green roofs on indoor temperature of buildings, the effect of different types of roofs on the air conditioning loads, and the life cycle cost of buildings with different types of roofing. The study was conducted in several phases: initial small-scale models to determine the heat flow characteristics of roof top soil layers with different thicknesses, a large-scale model applying the findings of the small-scale models to determine temperature fluctuations within a building with other common roofing systems, a computer simulation to investigate air conditioning loads in a typical building with cement fiber sheets and green roof slabs, a comparative analysis of the effect of traditional type roofs and green roofs on the air conditioning loads, and finally an analysis to predict the influence of traditional type roofs and green roofs on life cycle cost of the buildings. The main findings of the study were that green roofs are able to reduce the indoor temperature of buildings and are able to achieve better heat transfer through the roof, and, thus a lower cooling load is necessary for air conditioning and has the possibility of reducing life cycle cost of a building.

scholarly journals LARGE SCALE MODEL TESTS OF PLACED STONE BREAKWATERS

1976 ◽  
Vol 1 (15) ◽  
pp. 147 ◽  
Author(s):  
Charles K. Sollitt ◽  
Donald H. Debok
Keyword(s):  
Large Scale ◽  
Scale Model ◽  
Small Scale ◽  
Stable Model ◽  
Model Studies ◽  
Drag Forces ◽  
Port Facilities ◽  
Large Scale Model ◽  
Wave Heights ◽  
Water Depths

Large scale model studies reveal that Reynolds scaling can affect the apparent stability and wave modifying properties of layered breakwater structures. Results of a study for a breakwater configuration designed to protect offshore power and port facilities in water depths to 60 feet are presented and discussed. The armor layer of this structure is formed from quarried rock of irregular rectangular parallelepiped shape, individually placed perpendicular to 1:2 seaward slope and crest. The resulting armor layer is relatively smooth, densely packed and very stable. Model studies of similar configurations were studied at 1:10, 1:20 and 1:100 scale ratios. Stability, runup, rundown and reflection were measured for a variety of water depths, wave heights and periods. Analysis of the large scale test results establish that the placed stone armor is approximately as stable as dolos armor units. Runup, rundown and reflection respond similar to rough, impermeable slopes. Comparison of large and small scale results demonstrate that relative increases in drag forces at lower Reynolds numbers decrease stability and runup in small scale models.

Small-Scale Models for Testing Masonry Structures

2010 ◽  
Vol 133-134 ◽  
pp. 497-502 ◽  
Author(s):  
Alvaro Quinonez ◽  
Jennifer Zessin ◽  
Aissata Nutzel ◽  
John Ochsendorf
Keyword(s):  
Large Scale ◽  
Low Cost ◽  
Three Dimensional ◽  
Model Testing ◽  
Scale Model ◽  
Small Scale ◽  
Material Strength ◽  
Masonry Structures ◽  
Scale Models ◽  
Set Up

Experiments may be used to verify numerical and analytical results, but large-scale model testing is associated with high costs and lengthy set-up times. In contrast, small-scale model testing is inexpensive, non-invasive, and easy to replicate over several trials. This paper proposes a new method of masonry model generation using three-dimensional printing technology. Small-scale models are created as an assemblage of individual blocks representing the original structure’s geometry and stereotomy. Two model domes are tested to collapse due to outward support displacements, and experimental data from these tests is compared with analytical predictions. Results of these experiments provide a strong understanding of the mechanics of actual masonry structures and can be used to demonstrate the structural capacity of masonry structures with extensive cracking. Challenges for this work, such as imperfections in the model geometry and construction problems, are also addressed. This experimental method can provide a low-cost alternative for the collapse analysis of complex masonry structures, the safety of which depends primarily on stability rather than material strength.

Vibration Characteristics of a 50MW Francis Type Hydro Power Plant

2018 ◽  
Author(s):  
Y. Cho ◽  
Y. R. Oh ◽  
J. W. Choi ◽  
Y. J. Kim ◽  
J. Novotny ◽  
...  
Keyword(s):  
Power Plant ◽  
Hydroelectric Power Plant ◽  
Vibration Characteristics ◽  
Operating Conditions ◽  
Scale Model ◽  
Small Scale ◽  
Hydroelectric Power ◽  
Rotating Shaft ◽  
Engineering Structures ◽  
Hydro Power

Vibration characteristics of the rotating machinery has been usually managed to facilitate the deterioration of the equipment and to prevent accident in advance. In a hydropower turbine, pressure pulsation characteristics to induce vibration is investigated during the model testing with a small scale model turbine for various operating conditions, and a prototype turbine is constructed to operate stably on the site. However, the model test has limitation that can’t be considered together with the vibration characteristics of a generator itself and of civil engineering structures for the building that support a turbine and a generator. Therefore, field tests of vibration for a hydroelectric power plant are carried out periodically, thereby maintaining reliability for safe operation of power generation facilities. In the study, the vibration of a Francis type hydroelectric power plant operated over 30 years and overhauled a year and a half ago was measured and its characteristics has been investigated. Displacement and velocity sensors were installed at appropriate positions to measure the vibration of the rotating shaft and bearing support of a turbine and a generator, and the vibration characteristics of a typical hydroelectric power plant have confirmed by analyzing the measurement results. The vibration characteristics of rotating shaft and non-rotating parts of the hydroelectric turbine have been analyzed to confirm the degree of aging of the plant. Vibration in the power plant building depending on the operating conditions was also measured to be large enough to sense, and its frequency characteristics were analyzed.

New Efficient Sparse Space–Time Algorithms for Superparameterization on Mesoscales

2009 ◽  
Vol 137 (12) ◽  
pp. 4307-4324 ◽  
Author(s):  
Yulong Xing ◽  
Andrew J. Majda ◽  
Wojciech W. Grabowski
Keyword(s):  
Large Scale ◽  
Space Time ◽  
Horizontal Velocity ◽  
Specific Humidity ◽  
Scale Model ◽  
Small Scale ◽  
Squall Lines ◽  
Scale Models ◽  
New Algorithms ◽  
Small Scale Model

Abstract Superparameterization (SP) is a large-scale modeling system with explicit representation of small-scale and mesoscale processes provided by a cloud-resolving model (CRM) embedded in each column of a large-scale model. New efficient sparse space–time algorithms based on the original idea of SP are presented. The large-scale dynamics are unchanged, but the small-scale model is solved in a reduced spatially periodic domain to save the computation cost following a similar idea applied by one of the authors for aquaplanet simulations. In addition, the time interval of integration of the small-scale model is reduced systematically for the same purpose, which results in a different coupling mechanism between the small- and large-scale models. The new algorithms have been applied to a stringent two-dimensional test suite involving moist convection interacting with shear with regimes ranging from strong free and forced squall lines to dying scattered convection as the shear strength varies. The numerical results are compared with the CRM and original SP. It is shown here that for all of the regimes of propagation and dying scattered convection, the large-scale variables such as horizontal velocity and specific humidity are captured in a statistically accurate way (pattern correlations above 0.75) based on space–time reduction of the small-scale models by a factor of ⅓; thus, the new efficient algorithms for SP result in a gain of roughly a factor of 10 in efficiency while retaining a statistical accuracy on the large-scale variables. Even the models with ⅙ reduction in space–time with a gain of 36 in efficiency are able to distinguish between propagating squall lines and dying scattered convection with a pattern correlation above 0.6 for horizontal velocity and specific humidity. These encouraging results suggest the possibility of using these efficient new algorithms for limited-area mesoscale ensemble forecasting.

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