• Structural Engineering and Mechanics
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• v.53 no.1
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• pp.159-172
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• 2015

This paper is concerned with effects of the wall flexibility on the seismic behavior of ground-supported cylindrical silos. It is a well-known fact that almost all analytical approximations in the literature to determine the dynamic pressure stemming from the bulk material assume silo structure as rigid. However, it is expected that the horizontal dynamic material pressures can be modified due to varying horizontal extensional stiffness of the bulk material which depends on the wall stiffness. In this study, finite element analyses were performed for six different slenderness ratios according to both rigid and flexible wall approximations. A three dimensional numerical model, taking into account bulk material-silo wall interaction, constituted by ANSYS commercial program was used. The findings obtained from the numerical analyses were discussed comparatively for rigid and flexible wall approximations in terms of the dynamic material pressure, equivalent base shear and bending moment. The numerical results clearly show that the wall flexibility may significantly affects the characteristics behavior of the reinforced concrete (RC) cylindrical silos and magnitudes of the responses under strong ground motions.

• Advances in concrete construction
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• v.7 no.2
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• pp.65-74
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• 2019

This paper reports on the results of a parametric study, which examines the effects of varying aspect ratios on the dynamic response of cylindrical silos directly supported on the ground under earthquake loading. Previous research has shown that numerical models can provide considerably realistic simulations when it comes to the behavior of silos by using correct boundary conditions, appropriate element types and material models. To this end, a three dimensional numerical model, taking into account the bulk material-silo wall interaction, was produced by the ANSYS commercial program, which is in turn based on the finite element method. The results obtained from the numerical analysis are discussed comparatively in terms of dynamic material pressure, horizontal displacement, equivalent base shear force and equivalent bending moment responses for considered aspect ratios. The effects experienced because of the slenderness of the silo in regards to the seismic response were evaluated along with the effectiveness of the classification system proposed by Eurocode in evaluating the loads on the vertical walls. Results clearly show that slenderness directly affects the seismic response of such structures especially in terms of behavior and the magnitude of the responses. Furthermore the aspect ratio value of 2.0, given as a behavioral changing limit in the technical literature, can be used as a valid limit for seismic behavior.

• Computers and Concrete
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• v.18 no.1
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• pp.53-68
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• 2016

In this study, an investigation is made from the statics and economic aspects of the possibility of using the composite material ferrocement on the surfaces of squat cylindrical grain silos. For this purpose, the geometry of two model silos, each of height 5 m and diameter 5 m and 12.5 m, was designed. Five different reinforced plates of 10 and 20 mm thickness were produced to research the most suitable ferrocement plates to be used on the surface of these silos. Most durable reinforcement type for covering the silo surface was determined by pressure and bending tests. Grade 30 and Grade 55 steel plates were also considered for use in covering steel-coated silos. In the statics analysis performed with SAP2000, the least plate thicknesses needed for silos surfaced with Grade 30 and Grade 55 steel were found to be 6.20 mm and 4.70 mm respectively for silos of diameter 5 m, and 6.70 mm and 5.00 mm for silos of diameter 12.5 m. In the economic analysis, it was found that 20 mm thick Type 4 (with a wire diameter of 0.30 mm and a mesh aperture of $2mm{\times}2mm$ square type) reinforced ferrocement surfacing material was 5.6-6.1 times more economical than Grade 30 steel surfacing material and 4.4-4.7 times more economical than using Grade 55 steel. These results show that ferrocement can be used in place of steel from the point of view both of statics and economy.

• Structural Engineering and Mechanics
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• v.62 no.4
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• pp.487-496
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• 2017

The focus of this study were to investigate patterns between wall pressures and stresses with grain moisture of soybean and rice varieties widespread cultivated in Turkey in order to determine needed designing parameters for structure analysis in silos at filling and discharge. In this study, the wall pressures and stresses were evaluated as a function of moisture contents in the range of 8-14% and 10-14% d.b. The pressures and von Mises stresses affected as significant by the change of grain moisture content. The main cause of pressure and stress drops is changed in bulk density. Therefore is extremely important bulk density and moisture content of the product at the structural design of the silos. 4 mm wall thickness, were determined to be safe for von Mises stresses in both soybean and rice silos is smaller than 188000 kPa.

• Explosives and Blasting
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• v.27 no.2
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• pp.12-18
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• 2009

Recently, several cases of destruction of old cylindrical silos by explosive demolition method have been reported. This study deals with the subject concerning the pre-weakening of a cylindrical concrete silo for the application of overturning explosive demolition method. In the past, the pre-weakening operation of structure in explosive demolition has been done by use of some empirical methods. These empirical approaches, however, have possibilities of unexpected accidents. In order to provide a guideline for the pre-weakening of cylindrical silos and similar structures, this paper shows the result of a case study, in which the instability of a silo due to pre-weakening is investigated by a numerical structural analysis before actually conducting pre-weakening and demolition operations.

• Structural Engineering and Mechanics
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• v.4 no.3
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• pp.227-242
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• 1996

An important class of problems in the field of geotechnical engineering may be analyzed with the aid of a simple integro-differential equation. Behavior of "rigid" piles(say concrete piles), "deformable" piles(say gravel piles), pile groups, pile-raft foundations, heavily reinforced earth, flow within circular silos and down drag on cylindrical structures (for example the crusher unit of a mineral processing complex) are the type of situations that can be handled by this type of equation. The equation under consideration has the form; $$\frac{{\partial}w(r,\;z)}{{\partial}z}+f(z){\int}^z_0g({\xi})(\frac{{\partial}^2w(r,\;{\xi})}{{\partial}r^2}+\frac{1}{r}\frac{{\partial}w(r,\;{\xi})}{{\partial}r})d{\xi}+h(r,\;z)=0$$ where w(r, z) is the vertical displacement of a soil particle expressed as a function of the polar cylindrical space coordinates (r, z) and the symbols f, g and h represent soil properties and the loading conditions. The merit of the analysis is its simplicity (both in concept and in application) and the ease with which it can be expressed in a computer code. In the present paper the analysis is applied to investigate the behavior of a single rigid pile to bedrock. The emphasis, however, is placed on developing the equation, the numerical techique used in its evaluation and validation of the technique, hereafter called the ID technique, against a formal program, CRISP, which uses the FEM.

• Magazine of the Korean Society of Agricultural Engineers
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• v.27 no.2
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• pp.38-46
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• 1985

The reinforced concrete farm silos on the elastic foundatin are widely used in agricultural engineering because of their superior structural performance, economy and attractive appearance. Various methods for the analysis and design of farm silo, such as the analytical method, the finite difference method, and the finite element methods, can be used. But the analytical procedure can not be applied for the intricate conditions in practice. Therefore lately the finite element method has been become in the structural mechanics. In this paper, a method of finite element analysis for the cylindrical farm silo on ffness matrix for the elastic foundation governed by winkler's assumption. A complete computer programs have been developed in this paper can be applicable not only to the shell structures on elastic foundation but also to the arbitrary three dimensional structures. Assuming the small deflection theory, the membrane and plate bending behaviours of flat plate element can be assumed mutually uncoupled. In this case, the element has 5 degrees of freedom per node when defined in the local coordinate system. However, when the element properties are transformed to the global coordinates for assembly, the 6th degree of freedom should be considered. A problem arises in this procedure the resultant stiffness in the 6th degree of freedom at this node will be zero. But this singularity of the stiffness matrix can be eliminated easily by merely replacing the zero diagonal by dummy stiffness.