Papers by Keyword: Ductility

Abstract: The purpose of the present study is to evaluate the processing property of Mg96Zn2Y2 of casting material. Mg96Zn2Y2 is a high strength magnesium alloy material newly developed by Mr. Kawamura in Japan. The name of this alloy is called as 'Kumadai Goukin'. For this purpose, cylinder upsetting tests were performed. In addition, the marketing community of AZ31 magnesium alloy collates the information with the new material. We examined and compared the deformation resistance and ductility of the two materials. Furthermore, the dependence of deformation resistance and ductility of these materials to processing temperature and speed was evaluated [1].

Abstract: In order to obtain the effect of fibers on fractural property of mass concrete, it had investigated physical performance, elastic modulus and bending toughness of mass concrete with the presence of steel fiber and polypropylene fiber(PPF). Results showed that the inclusion of PPF caused a slight decrease in initial cracking strength, flexural strength and elastic modulus, yet resulted in small increase in equivalent flexural strength, capacity-carrying loading variation coefficient and toughness.The presence of steel fiber was of significance to increase initial-cracking strength, flexural strength and equivalent flexural strength, and produced a slight increase in elastic modulus and significant improvement in capacity-carrying variation coeffecient and flexural toughness. Overall, the inclusion of steel fiber is rated better than PPF in improving ductility and crack resistance of concrete.

Abstract: As a key part in concrete-filled steel tubular frames, the seismic behavior of joints between concrete-filled steel tubes and beams needs more research because of the complexity of stress under the reciprocating load. the behavior of 9 strengthened joints connecting concrete-filled steel tube with H-shaped steel beam have been analyzed under reversed cyclic loading condition by using finite element analysis software ANSYS, and the result show that: (1) The ultimate bearing capacity, energy dissipation capacity and ductility of strengthened joint are obvious better than that of ordinary welded joint; (2) Compared to concrete-filled steel tube the ultimate bearing capacity, energy dissipation capacity and ductility of double-layer concrete-filled steel tubes are better; (3) For the joints connecting double-layer concrete-filled steel tubes with beams, the shape of inner tube have certain effect on the ultimate bearing capacity but little on the energy dissipation capacity and ductility. (4) The shape of stiffened plate has significant influence on the ultimate bearing capacity, energy dissipation capacity and ductility of nodes.

Abstract: The behavior of confined concrete is highly dependent on the confinement type of transverse reinforcement, spiral hoops are generally believed to have better confined effect in concrete than rectangular hoops. It is verified through experiments and the oretical calculations that multi-spiral confined concrete columns have better mechanical properties than single spiral columns, the multi-spiral significantly increase the column’s strength, plasticity, ductility and anti-seismic capability. Based on the three-direction stress law of confined concrete, the load carrying capacity of the rectangular cross section concrete column with multi-spiral is analysed in this paper, and the calculated equation of the load carrying capacity is proposed, which provide a theory and calculation basis for multi-spiral confined concrete column design and research.

Abstract: The buckling-restrained braces(BRBs) with low yield strength(LYS) steel make good use of ductility and hysteretic energy dissipation of the low yield strength steel and are gradually applied in structural vibration. To foster BRBs with low yield strength steel in China mainland, the domestic LYS160 was used in BRB. The cross section was a simple shape. A static cyclic test was carried out, and the finite element analysis was conducted. The results show that the BRB with domestic low yield strength steel has good ductility, hysteretic energy dissipation and resistance to fatigue. A shaped cross section is simple and easy to promote application in China mainland.

Abstract: Mg96Zn2Y2 is a high strength magnesium alloy material developed by Mr. Kawamura in Japan. The name of this alloy is called as 'Kumadai Goukin'. The purpose of the present study is to evaluate the processing property of Mg96Zn2Y2 material. For this purpose, cylinder upsetting tests were performed. In addition, the marketing community of AZ31 magnesium alloy collates the information with the new material. We examined and compared the deformation resistance and ductility of the two materials. Furthermore, the dependence of deformation resistance and ductility of these materials to processing temperature and speed was evaluated [1],[2].

Abstract: In order to increase the strengthening efficiency of steel bar mat-mortar (BM) jacket and wire mesh-mortar (WM) jacket around existed circular concrete columns, an attempt to strengthen the columns with hybrid bar mat-wire mesh-mortar (HBWM) jacket was proposed. A comparatively experimental study on axial compression behaviors of concrete columns wrapped with three different strengthening systems, namely BM, HWBM and carbon fiber reinforced polymer (CFRP) was performed. The experiment results showed that much more cracks appeared in HWBM columns compared with those in BM columns. As a result, on the premise that the concrete compressive strength of the HWBM columns increased 90% compared with that of the BM columns, the ductility of the HWBM columns reached about twice as that of the BM columns. The increase of the concrete compressive strength of CFRP strengthened columns was higher than those of HWBM and BM strengthened columns. The ductility of CFRP strengthened columns, however, was obviously lower than that of HWBW columns.

Abstract: Unreinforced stone masonry is common in heritage structures worldwide. Unfortunately, these structures are susceptible to failure or severe damage when subject to dynamic or seismic loading. Conservation of historic structures is a challenge as the heritage and cultural values need to be preserved while the advent of new seismic codes may require major strengthening to be implemented. The new seismic codes demand high seismic strength and ductility for such structures, whereas neither the strength nor the ductility of an existing stone masonry building can be quantified easily. The Parliament buildings of Canada fall into this category. Therefore, an extensive experimental program was carried out to investigate the dynamic and seismic behaviours of stone walls representative of Canada’s Parliament buildings. The walls were constructed of double stone wythes with the cavity between being filled with weak mortar, shards and small stones, constituting a rubble core of the walls. The experimental program included in-plane quasi-static, free vibration and high frequency loadings, together with out-of-plane shake table tests. The tests were aimed at investigating the integrity, strength, damping, stiffness degradation, and ductility of the walls. Different potential strengthening methods were assessed, methods that would minimize structural intervention and preserve the heritage values of the building. The methods involved different metallic anchors and traditional stone interlocking to tie the two outer wythes together. Fortunately, the stone walls exhibited satisfactory performance in all cases. In addition, the test results suggested that plain un-strengthened stone walls had strength and other characteristics similar to those of the rehabilitated walls, in the range of the imposed load scenarios.

Abstract: It is well known that the formation of a highly hardening state of the standard steels is related with the improvement of its mechanical characteristics, which means an increment in the ductility of the fracture. Commonly, the ductility of the fracture is measured by means of mechanical methods involving large size and geometrical special shape of the sample. Satisfy these requirements in the initial steps of the development of a new material, or during the treatment for improving the hardness, is a dif ficult task. The present work shows the theoretical determination of the ductility of the fracture when the researchers have a small piece of the sample. Also, from the analysis of microscopy images, by the first time, it is demonstrated that an ultra-hardening state of the steel corresponds to a nano-fragmented dislocational structure in accordance to the theory.

Abstract: In order to study the characteristics of fine grained polycrystalline metals, it is important to recognize the function of grain boundaries (GB), crystal defects such as dislocation and/or nanoscale voids, since the fraction of GB increases as grain sizes decreases, the deformation process of these metals could be different from those in larger size grains. In this study, we first evaluate the hypothesis that GB behaves as dislocation source and sink during the deformation of fine grained metal, then compare the behavior between GB and a tiny defect from the view point of dislocation source and sink phenomena. Since continuous dislocation supplies could be considered as the key issue to improve the toughness of fine grained metals, this concept could be helpful to design next generation polycrystalline metals.