Papers by Keyword: Experimental Test

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Authors: Hui Ge Xing, Da Lu Tan, Fu Gang Xu
Abstract: The stress-strain of triaxial rheological test for rock can be divided into three stages: initial attenuation rheological stabilization rheoligical and speedup rheological stages, the damage is rapid increased in the speedup stage. Damage mechanics is introduced into the Nishihara rheological model, a new rheological constitutive model is established which is combined with the concept of effective stress. The mechanical parameters are recognized by the experimental test data of greenschist. Computing result shows that, the presented model can described the mechanical characteristics in different rheological stage very well, and the error between simulated result and test data is small.
647
Authors: Hai Jun Zhou, Hong Hong Huang, Hua Zhang
Abstract: An experimental study on mechanical behavior of superelastic NiTi shape memory alloy (SMA) bar subjected to torsion was made. The SMA specimen was in round bar shape, material phase was austenite and stress mode was torsion. The test was carried out by applying repeated cyclic uniform torsional load. Strain rate, strain amplitude and number of cycles were considered as test parameters. The test was described and analyzed in terms of three fundamental mechanical quantities: secant stiffness, energy loss per unit weight and equivalent damping. The test results show that SMA bar subjected to torsion, have great potential for application in seismic devices due to their considerable superelasticity and stable cyclic behaviors.
3992
Authors: Martin Krejsa, Jiri Brozovsky, David Mikolasek, Premysl Parenica, Libor Zidek, Jaroslav Kozak
Abstract: The paper describes the experimental tests of steel bearing elements, which were aimed at obtaining material, geometric and strength characteristics of the fillet welds. Preparation of experiment consisted in defining of numerical models of tested samples using FEM analysis and the commercial software ANSYS. Data obtained from described experimental tests are necessary for further numerical modelling of stress analysis of steel structural supporting elements.
412
Authors: Kang Hai Tan, Bo Yang
Abstract: Firstly, this paper presents an overview of DoD code [1] against progressive collapse and points out the shortcomings of the current design approaches. After that, seven experimental tests of common types of bolted steel beam-column joints under a middle-column removal scenario are presented. This study provides the behaviour and failure modes of different types of connections, including their resistances and rotational capacities in catenary action. The test results indicate that the web cleat connection has the best performance in the development of catenary action. The flush end plate, fin plate and top and seat with web angle (TSWA) connections could also deform in a ductile manner and develop catenary action prior to failure. Numerical simulations have also been conducted. Both static and explicit dynamic solvers were employed to overcome problems of non-convergence, contact, large deformation and fracture simulations. It is demonstrated that the finite element analyses give reasonable accuracy compared to the test results. In addition, an extensive parametric study was undertaken using these validated models to obtain the rotation capacities of various types of connections under catenary action. Finally, some practical design implications have been drawn up from the experimental tests and the parametric study. A new tying resistance expression is proposed to consider the effect of large rotation. If large rotation capacity is not considered in the design stage, the joints with poor rotation capacities would fail to achieve the design tying resistances. In addition, four new connection acceptance criteria of rotation capacities have been proposed to incorporate catenary action under a middle column removal scenario. The work shows that current acceptance criteria of rotation capacities for steel joints such as web cleat, fin plate, flush end plate and TSWA connections, are probably too conservative as they only consider pure flexural resistance.
1330
Authors: Luís Magalhães, Carlos Rebelo, Sandra Jordão
Abstract: This article presents some results of the experimental monotonic bending tests on the behaviour of the tubular columns and the reverse channel, effected based on a parametric variation of the most significant characteristics of the tubular profiles. The parameters considered are the thicknesses and the widths of the tubular columns faces, the filling with concrete and the axial load. The experimental tests program, included in the framework of the Doctoral Program Thesis in the scientific domain of the Steel Composite Structures, were performed on a test layout, corresponds to a framed structure, in the Structural Mechanic Laboratory of the Department of Civil Engineering of the University of Coimbra. The objective is to determine the characteristics of the nonlinear cyclic behaviour of the principal components of the tubular columns and the reverse channel, in this shape of joints. These components are related to the tubular columns walls, and to the web and flanges of the reverse channel yielding, crushing or instability, when submitted to bending, shear, compression and tension. The results of this experimental tests allow correlate the parameters considered with the structural behaviour of the connection, defined by the resistance, the stiffness, and the rotation capability.
458
Authors: Laura Anania, Antonio Badalà, Giuseppe D’Agata
Abstract: In the past two decades, CFRP had been used to strengthen and repair r.c. structures and recently it is also employed to strengthen historical or monumental buildings constituted by masonry structure. However, premature failure due to debonding of the FRP is one of the important issues still to be resolved. Numerous word wide research studies have dealt with the debonding problem in r.c. structures but only a few works were carried out in the masonry structures area. So, the study of the global behaviour of the reinforced masonry element seems to be very useful, both for a congruous design and to verify the strengthening strategy. To this aim, this paper summarizes the debonding phenomena between C-FRP strip and natural calcareous rock brick, employed in our buildings, by means of a testing investigation. Two different kinds of anchorage were designed and employed for the tested samples: standard and reinforced anchorage. The experimental tests carried out on the specimens permits us to compare the effective bond length, with the one obtained by International rules and especially with the Italian CNR-DT200/2004 formulation and to say that the effective bond length dictates by the rules undervalues the experimental data. The data obtained permit us also to know the shear-slip delamination curve useful for the numerical investigation, as well as both the failure mode and the "II mode" fracture energy.
1091
Authors: Emidio Nigro, Antonio Bilotta, Giuseppe Cefarelli, Gaetano Manfredi, Edoardo Cosenza
Abstract: Experimental tests were recently performed to evaluate resistance and deformability of nine concrete slabs reinforced with Fiber Reinforced Polymer (FRP) bars in fire situation by varying (a) external loads in the range of the service loads, (b) concrete cover in the range of usual values (30-50mm), (c) bar end shape (straight or bent) and its length at the end of the concrete members, namely in the zone not directly exposed to fire (250-500mm). Experimental results showed the importance of concrete cover in the zone directly exposed to fire for the protection provided to FRP bars, due to its low thermal conductivity. Moreover, the length of the FRP bars in the zone of slab not directly exposed to fire and its shape at the end of the members was crucial to ensures slab resistance once the resin softening reduced the adhesion at the FRP-concrete interface in the fire exposed zone of slab. In particular the anchorage obtained simply by bending bars at the end of member in a short zone (250mm) allowed attaining a good structural behavior in case of fire equivalent to that showed by slabs characterized by a large anchoring length (500mm). Tests results are briefly compared and discussed in this paper, whereas the behavior of the bar anchorage is carefully examined based on both the results of numerical thermal analysis and the predictions of a bond theoretical model adjusted for fire situation.
533
Authors: Mihai Fofiu, Andrei Bindean, Valeriu Stoian
Abstract: This paper presents the retrofitting procedure used on a precast reinforced concrete wall panel (PRCWP) in order to restore its initial load bearing capacity. The specimen used in this experimental test is one from the residential multistoried buildings constructed in Romania from the 1970 onwards. All of the characteristics of the element are from the specific era, only scaled down with a factor of 1:1,2. The element was subjected to in-plane reversed cyclic loading to simulate its seismic behavior and obtain its maximum load bearing capacity. After the test we retrofitted the element using Carbon Fiber Strips Externally Bonded (EBR) and anchored with Carbon Fiber Reinforced Polymers (CFRP) mesh. The porpoise of the paper is to compare the maximum loading bearing capacity of the unstrengthen and strengthen elements in order to compare them and examine the efficiency of this retrofitting procedure.
208
Authors: Si Huang, Yue Le, Luo Li
Abstract: This paper presents a numerical simulation and experimental study on a solid-liquid hydrocyclone. In the simulation, the standard k-ε turbulence model and the zero-equation model are employed to compute the flow field of the two phases in the hydrocyclone under different conditions, such as viscosity of the liquid, particle size and flow rate. In the experiment, a hydrocyclone is manufactured and measured for the separation efficiency and pressure drop in the test system. The simulation result of hydrocyclone performance matches well with the experimental data.
1606
Authors: Wouter de Corte, Veerle Boel
Abstract: Self compacting concrete is a concrete mixture specifically designed not to require external energy for compaction. This property results in many advantages for precast as well as ready-mix concrete applications. Especially, dense reinforcements or slender elements can be achieved. However, in current design codes this concrete is treated as traditional concrete although the mix composition is substantially different. Due to a decrease in coarse aggregates, combined with a higher amount of chemical and mineral admixtures, the overall mechanical behavior may differ from that of traditional concrete even when the compressive strength of both mixtures are equal. This is especially visible in the crack formation in the tensile zone of concrete beams. This paper presents results of an analysis of crack formation, distribution and width on reinforced concrete beams with varying reinforcement ratios. Differences in crack properties, favoring self-compacted over traditional concrete are found for all considered reinforcement ratios, although the results are less pronounced for the higher ratios. The results may allow a favorable serviceability limit state criteria for this material.
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