Abstract
This paper reports an experimental study into the rheological behaviour of self consolidating concrete (SCC). The investigation aimed at quantifying the impact of the varying amounts of mineral admixtures on the rheology of SCC containing natural sand. Apart from the ordinary Portland cement (OPC), the cementitious materials such as fly ash (FA), ground granulated blast furnace slag (GGBS) and micro-silica (MS) in conjunction with the mineral admixtures were used in different percentages keeping the mix paste volume and flow of concrete constant at higher atmospheric tempterature (30ᵒ to 40ᵒC). The rheological properties of SCC were investigated using an ICAR rheometer with a four-blade vane. The rheological properties of self-consolidating concrete (SCC) containing different mineral admixtures (MA) were investigated using an ICAR rheometer. The mineral admixtures were fly ash (FA), ground granulated blast furnace slag (GGBS), and micro silica (MS). The results obtained using traditional workability results are compared with those obtained using ICAR rheometer. The instrument ICAR (International Center for Aggregate Research) rheometer employed in the present study for evaluating the rhelogical behaviour of the SCC is found to detect systematic changes in workability, cementitious materials, successfully. It can be concluded that the rheology and the slump flow tests can be concurrently used for predicting the flow behaviours of SCC made with different cementitious materials.
Address
Sunil D. Bauchkar and H.S. Chore : Department of Civil Engineering, Datta Meghe College of Engineering, Sector-3, Airoli, New Mumbai, 400708, India
Abstract
In this study, the optimum silo dimensions for the barrel-type steel-concentrated silo with a conical outlet port usable in the hazelnut storage were investigated. Three different types of silo models as Model 1 (1635 tons), Model 2 (620 tons) and Model 3 (1124 tons) were used in the study. Varying wall thicknesses were used for Model 1 (10, 11, 12, 13, 14, 15 and 20 mm), Model 2 (10, 15 and 20 mm) and Model 3 (10, 15 and 20 mm) silos. For Model 1 silo has the most storage capacity here, to determine its optimum wall thickness, the wall thicknesses of 11, 12, 13 and 14 mm were used as different from the other models. Thus the stresses occurring in different lines with ANSYS finite element software were examined. In the study it was determined that the 10, 11 and 12 mm wall thicknesses of the Model 1 silo are not safe in terms of the stresses caused by the vertical pressure loads in the filling conditions. From the view of the filling and discharge conditions, other wall thicknesses and model silos were diagnosed to be secure. The optimum silo dimensions which won\'t cause any structural problems have been found out as the Model 1 silo with a 13 mm wall thickness when the filling capacity and the maximum von Mises stresses are taken into account. This barrel-type silo with conical outlet port sets forth the most convenient properties in hazelnut storing in terms of engineering.
Key Words
hazelnut; silo; Eurocode 1; ANSYS finite element software
Address
Hakan Kibar : Department of Biosystems Engineering, Faculty of Agriculture, Igdir University, Igdir, Turkey
Turgut Ozturk : Department of Agricultural Structures and Irrigation, Faculty of Agriculture, Ondokuz Mayis University, Samsun, Turkey
Abstract
This study deals with the design of bridge girder structures and consists of two parts. In the first part an optimal bridge girder topology is determined using a software based on structure compliance minimization with constraints imposed on the body mass, developed by the authors. In the second part, an original way in which the topology is mapped into a bridge girder structure is shown. Additionally, a method of converting the thickness of the bars obtained using the topology optimization procedure into cross sections is introduced. Moreover, stresses and material consumption for a girder design obtained through topology optimization and a typical truss girder are compared. Concluding, this paper shows that topology optimization is a good tool for obtaining optimal bridge girder designs.
Key Words
topology optimization; minimum compliance; design of bridge truss girders
Address
Ryszard Kutylowski : Institute of Civil Engineering, Wroclaw University of Technology, Wyb. Wyspiańskiego 27, Poland
Bartosz Rasiak : Alpine Bau GmbH, Polish Branch, Poland
Abstract
It is shown that topology optimization is a valuable tool for the design of bridge girders. This paper is a follow-up to (Kutylowski and Rasiak 2014) and it includes an analysis of truss members\' outer dimensions dictated by the standards. Moreover, a frame bridge girder mapped from a selected topology is compared with a typical frame girder on the basis of (Kutylowski and Rasiak 2014). The analysis shows that topology optimization by means of the proposed algorithm yields a topology from which one can map a frame bridge girder requiring less material for its construction than the typical frame girder currently used in bridge construction.
Key Words
topology optimization; design of frame bridge girders; topology and design parameters analysis
Address
Ryszard Kutylowski : Institute of Civil Engineering, Wroclaw University of Technology, Wyb. Wyspiańskiego 27, Poland
Bartosz Rasiak : Alpine Bau GmbH, Polish Branch, Poland
Abstract
In this study, two beam-column elements based on the Elasto-Fiber element theory for reinforced concrete (RC) element have been developed and compared with each other. The first element is based on Elasto Fiber Approach (EFA) was initially developed for steel structures and this theory was applied for RC element in there and the second element is called as Fiber & Bernoulli-Euler element approach (FBEA). In this element, Cubic Hermitian polynomials are used for obtaining stiffness matrix. The beams or columns element in both approaches are divided into a sub-element called the segment for obtaining element stiffness matrix. The internal freedoms of this segment are dynamically condensed to the external freedoms at the ends of the element by using a dynamic substructure technique. Thus, nonlinear dynamic analysis of high RC building can be obtained within short times. In addition to, external loads of the segment are assumed to be distributed along to element. Therefore, damages can be taken account of along to element and redistributions of the loading for solutions. Bossak-a integration with predicted-corrected method is used for the nonlinear seismic analysis of RC frames. For numerical application, seismic damage analyses for a 4-story frame and an 8-story RC frame with soft-story are obtained to comparisons of RC element according to both approaches. Damages evaluation and propagation in the frame elements are studied and response quantities from obtained both approaches are investigated in the detail.
Key Words
Elasto-Fiber element; Fiber & Bernoulli-Euler element; seismic damage analysis; dynamic substructure technique; Bossak-a method and predicted-corrected method
Abstract
The aim of this study is to investigate the effects of the beam aspect ratio(L/h), hole diameter, hole location and stacking layer sequence ([0/45/-45/90]s, [45/0/-45/90]s and [90/45/-45/0]s) on natural frequencies of glass/epoxy perforated beams under room and high (40, 60, 80, and 100\'C) temperatures for the common clamped-free boundary conditions (cantilever beam). The first three out of plane bending free vibration of symmetric laminated beams is studied by Timoshenko\'s first order shear deformation theory. For the numerical analyses, ANSYS 13.0 software package is utilized. The results show that the hole diameter, stacking layer sequence and hole location have important effect especially on the second and third mode natural frequency values for the short beams and the high temperatures affects the natural frequency values significantly. The results are presented in tabular and graphical form.
Key Words
layered structures; cut-out; natural frequencies; finite element analysis
Address
Yusuf Cunedioglu : Department of Mechanical Engineering, Faculty of Engineering, Nigde University, 51245 Nigde, Turkey
Bertan Beylergil : Department of Mechanical Engineering, Faculty of Engineering, Izmir Institute of Technology,
Gulbahce Campus, 35437 Urla, Izmir, Turkey
Abstract
This study focuses on seismic behaviour of tall piers characterized by high slender ratio. Two analysis models were developed based on elastic-plastic hinged beam element and elastic-plastic fiber beam element, respectively. The effect of the division density of elastic-plastic hinged beam element on seismic demand was discussed firstly to seek a rational analysis model for tall piers. Then structural seismic behaviour such as the formation of plastic hinges, the development of plastic zone, and the displacement at the top of the tall piers were investigated through incremental dynamic analysis. It showed that the seismic behaviour of a tall pier was quite different from that of a lower pier due to higher modes contributions. In a tall pier, an additional plastic zone may occur at the middle height of the pier with the increase of seismic excitation. Moreover, the maximum curvature reaction at the bottom section and maximum lateral displacement at the top turned out to be seriously out of phase for a tall pier due to the higher modes effect, and thus pushover analysis can not appropriately predict the local displacement capacity.
Abstract
The paper focuses on the dynamic response of a blast-invested glass-steel curtain wall supported by single-way pretensioned cables. In order to mitigate the critical components of the facade from severe structural damage, an innovative system able to absorb and dissipate part of the blast-induced stresses in the critical facade components is proposed. To improve the blast reliability of the studied glazing system, specifically, rigid-plastic and elastoplastic devices are introduced at the base and at the top of the vertical bearing cables. Several combinations and mechanical calibrations of these devices are numerically investigated and the most structurally and economically advantageous solution is identified. In conclusion, a simple analytical formulation totally derived from energetic considerations is also suggested for a preliminary estimation of the maximum dynamic effects in single-way cable-supported facades subjected to high-level blast loads.
Key Words
single-way cable-supported facade; explosions; dissipative devices; energy approach; nonlinear dynamic simulations
Address
Claudio Amadioa and Chiara Bedon : Department of Engineering and Architecture, University of Trieste, Piazzale Europa 1, 34127 Italy
Abstract
In the displacement based finite element analysis of composite beams that consist of two Euler-Bernoulli beams juxtaposed with a deformable shear connection, the coupling of the displacement fields may cause oscillations in the interlayer slip field and reduction in optimal convergence rate, known as sliplocking. In this study, the B-bar procedure is proposed to alleviate the locking effects. It is also shown that by changing the primary dependent variables in the mathematical model, to be able to interpolate the interlayer slip field directly, oscillations in the slip field can be completely eliminated. Examples are presented to illustrate the performance and the numerical characteristics of the proposed methods.
Key Words
composite beam; slip-locking; B-bar formulation; change of primary variables
Address
R. Emre Erkmen, Keith Crews : School of Civil and Environmental Engineering, University of Technology, Sydney, NSW 2007, Australia
Mark A. Bradford: School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052, Australia
Abstract
Stress determination is a very important step in the assessment of the safety of existing reinforced concrete structures. In rock mechanic this goal is achieved with the over-coring technique. The main idea behind such a technique is to isolate a material sample from the stress field in the surrounding mass and monitor its re-equilibrium deformation response. If the materials remains elastic, and elastic properties are known, stresses may be obtained from the corresponding measured strains. The goal of this paper is to evaluate if the over-coring technique is applicable to reinforced concrete members. The results of an experimental investigation on the behaviour of compressed concrete columns subjected to the over-coring technique are presented. Considerations about the range of applicability of the technique are made by comparing the measured and the theoretical stresses. After that, results of failure tests on drilled specimens are presented and discussed. Furthermore, the response is compared with that of columns core-bored before the compressive test. Finally, comparisons with numerical analysis are shown.
Key Words
experimental research; over-coring technique, RC columns; compressive tests; reduction of bearing capacity
Address
Giuseppe Campione : Dipartimento di Ingegneria Civile Ambientale Aerospaziale e dei Materiali DICAM, Universita di Palermo, Viale delle Scienze, 90128 Palermo, Italy
Giovanni Minafo : University
