Explore the vast range of titles available.

This study proposes a modification for the current design approach for square and rectangular silos that accounts for silos’ wall flexibility. First, the authors investigated the effect of wall stiffness symbolized by the wall width-to-thickness ratio (a/t) and silo’s dimensions, on the wall-filling pressure using a recently validated 3D finite element model (FEM). The model was then employed to predict the pressures acting on silos’ walls accounting for the stress state in stored granular materials. Most design formulas and guidelines assume silos’ walls to be rigid. This assumption is acceptable for the case of rigid wall concrete silos; however, it is questionable for semi-rigid, flexible wall metal silos. Consequentially, it is crucial to determine the minimum wall stiffness necessary to secure the applicability of the current design rigid wall assumptions and to propose a way to deal with semi-rigid and flexible walls. To this end, several wall pressure distributions that correspond to filling steel silos with varied wall thicknesses were studied. A new adjustment to the Janssen technique was proposed for a better estimate of the wall-filling pressures for square and rectangular silos. In the case of prismatic silos, the Eurocode uses the Janssen equation together with an equivalent radius of a corresponding circular silo (with the same hydraulic radius) to determine the wall pressure. This method predicts pressure values that are practically accurate for rigid-wall silos, but its accuracy decreases for semi-rigid and flexible-wall silos. As an enhancement, the Janssen equation was modified in this research to generate more accurate pressure estimates based on the equivalent volume concept. The finite element results of several developed models with the same granular material were compared to the estimations of the newly established approach to verify the broad range of its applicability.

This study develops and validates a 3-D finite-element model for lateral pressures in square, flat-bottomed steel silos, challenging the applicability of conventional design methods. The model, using Mohr–Coulomb for wheat and surface-to-surface contact, closely matches observed pressures and demonstrates that slenderness h/a determines the pressure regime: Janssen-type asymptotic profiles in slender silos (h/a ≥ 7.5) change to Rankine-type linear profiles in squat silos (h/a ≤ 1.5). Therefore, using slender-silo formulae for squat designs may lead to inaccurate estimations of base pressures. A parametric study evaluates material influences: lateral pressure is significantly affected by Poisson’s ratio (raising from 0.28 to 0.45 more than doubles base pressure, + 110%) and wall friction µ, while it shows little sensitivity to Young’s modulus and cohesion. These results provide design-oriented recommendations for the safe and cost-effective sizing of silos across various geometries and granular materials.

The construction industry has often been described as stagnant and out-of-date due to the lack of innovation and innovative work methods to improve the industry (WEF, 2016; Ostravik, 2015). The adoption of Building Information Modelling (BIM) within the construction industry has been relatively slow (Cao et al., 2017), particularly in the South African Construction and Built Environment (CBE) (Allen, Smallwood & Emuze, 2012). The purpose of this study was to determine the critical factors influencing the adoption of BIM in the South African CBE, specifically from a quantity surveyor’s perspective, including the practical implications. The study used a qualitative research approach grounded in a theoretical framework. A survey questionnaire was applied to correlate the interpretation of the theory with the data collected (Naoum, 2007). The study was limited to professionals within the South African CBE. The study highlighted that the slow adoption of BIM within the South African CBE was mainly due to a lack of incentives and subsequent lack of investment towards the BIM adoption. The study concluded that the South African CBE operated mainly in silos without centralised coordination. The BIM adoption was only organic. Project teams were mostly project orientated, seeking immediate solutions, and adopted the most appropriate technologies for the team’s composition. The study implies that the South African CBE, particularly the Quantity Surveying profession, still depends heavily on other role-players in producing information-rich 3D models. Without a centralised effort, the South African Quantity Surveying professionals will continue to adopt BIM technology linearly to the demand-risk ratio as BIM maturity is realised in the South African CBE.

Silos are used worldwide to store granular and powdered materials. Agricultural, food and feed products are commonly stored in silos. However, many questions remain unanswered about how to estimate the pressures applied by the bulk material, which are needed to design and calculate the structure of the silo. The complexity of the laws that govern the mechanical behavior of the stored material along with the low number of experimental stations in the world hinder progress in this field. The aim of this study was to elucidate the relationship of the hopper angle, flow pattern and vertical stress at the cylinder-to-hopper transition in slender silos. Therefore, a set of experiments was conducted on a test station to measure the vertical stress produced by maize at the cylinder-to-hopper transition. Five different hopper angles were used. The experiments comprised the filling, the static phase and the discharge. The results obtained show that the hopper angle influences the vertical stress at the cylinder-to-hopper transition. Some bottom configurations (flat bottom and bottom with an angle of 30°) led to vertical stresses that exceeded the value calculated according to Eurocode 1. It is clear that further experimental studies are still necessary to understand the underlying physical phenomena and the relations between pressures, silo geometry and flow pattern of the stored material.

Bringing together the leading European expertise in behaviour and design of silos, this important new book is an essential reference source for all concerned with current problems and developments in silo technology. Silos are used in an enormous range of industries and the handling characteristics of many industrial materials require different app Foreword Part 1: Silo Flow. Part 2: Concrete Structures. Part 3: Metal Structures. Part 4: Numerical simulation of particulate solids. Part 5: Silo Tests. Part 6: Experimental Techniques. Part 7: Research for Industry. Index.

There is extensive engineering literature concerning the prediction of pressure and flow in a silo. The great majority of them are based on continuum theories. The friction between the stored material and the silo wall as well as the inclination of the hopper at its base are considered to be the most influential parameters for the flow pattern within the silo. In this paper, the filling and discharge of a planar silo with a hopper at its base has been modelled using DEM. The aim is to investigate the influence of DEM model parameters on the predicted flow pattern in the silo. The parametric investigation particularly focused on the hopper angle of inclination and the contact friction between particles and walls. The shape of the particles was also considered by comparing spherical and non-spherical particles, thus providing an insight into how particle interlocking might influence solids flow behaviour in silos. The DEM computations were analysed to evaluate the velocity profiles at different levels as well as the wall pressure distribution at different stages during filling and discharge. A detailed comparison reveals several key observations including the importance of particle interlocking to predict a flow pattern that is similar to the ones observed in real silos.

Within the code-family of the Eurocodes, provisions for aluminium shells are given in EN 1999-1-5 (EC9) [1]. EC9-1-5 is listed in the Bavarian List of Technical Building Regulations. Thus, in Bavaria as well as in other Federal States of Germany it is mandatory to use EC9-1-5 for the verification of silos. A typical aluminium silo for industrial products might have a diameter of 3 m, a bin height of 10 m and wall thicknesses of 4 mm / 5 mm. The aluminium alloy EN AW-5754 [Al Mg3] O/H111 (EN 485-2 [2]) would be typical as well. Relevant for determining the required wall thickness is the buckling resistance under axial compression in the skirt and axial compression with coexisting internal pressure in the silo bin. When some obvious shortcomings in the formulae for coexisting internal pressure were investigated, it was found that there is a big discrepancy between scientific research, which has been done on the imperfection sensitivity of aluminium shells and the design equations in EC9-1-5. In the present paper an effort was made, in order to tackle these discrepancies and make clear, in which points the code needs amendment.

A new experimental device for the measurement of the hzorizontal to vertical stress ratio was developed. The tester is designed to conduct the required measurements using a single standard load cell without the need to apply strain gauges on custom built parts. Three different procedures were tested with free-flowing incompressible powders to determine the most precise procedure. This optimal procedure included the preliminary twisting of the cell lid to pre-shear the sample and was modified to conduct experiments with cohesive compressible powders. The results obtained from the best procedure were compared with those from commonly used estimating equations for the horizontal to vertical stress ratio as a function of the angle of internal friction. The obtained results were consistent with the Koenen equation (Koenen in Centralblatt der Bauverwaltung 16:446–449, 1896 ) for free-flowing materials and with the DIN 1055 equation (DIN 1055 Teil 6, Lastannahmen für Bauten, Lasten in Silozellen, 1987 ) for cohesive materials.

Handling of solid biomass poses some special challenges that are not present for liquid or gaseous fuels. Liquids and gases are relatively easy to handle, because they are fluid, which continuously deforms under a shearstress. Fluid easily takes the shape of any vessel they are kept in and flow easily under gravity, if they are heavier than air. For these reasons, storage, handling, and feeding of gases or liquids do not generally pose a major problem.

Silos are strategic structures widespread in the industrial sectors for post-harvest preservation purposes. Current standards on the seismic design of silos are understandably based on approximate and simplified assumptions, leading intentionally to conservative design-oriented formulae. However, unjustified over-estimation might lead to unnecessary economic losses. As part of the authors’ analytical and experimental ongoing research on the complex seismic behavior of filled silo systems, in this short paper, an in-depth reading of the theoretical framework originally proposed during the 1970s and 1980s is provided to present a better understanding of the unexplained design-oriented formula of the seismic additional pressure in the European standard. A conceptual incongruence in the Eurocode EN1998-4:2006 is pointed out and discussed regarding the dynamic overpressure formula in the case of ground-supported flat-bottom circular silos subjected to seismic excitation. Specifically, a potential miscounting of the geometrical aspect in circular silos, with respect to rectangular ones, leads to an inconsistent amplification of the additional pressures in the range 1.65–2, depending on the filling aspect ratio of the silo. This inconsistency provides the reason for several unexplained results recently published in the scientific literature. A proposal for a physically based correction, retaining the current assumptions made by the EN1998-4, is finally given.