Mechanical properties of novel out-of-plane steel beam–concrete wall pinned joints with T-shaped steel connectors under monotonic tension load

2019 ◽  
Vol 192 ◽  
pp. 71-85 ◽  
Author(s):  
He Zhao ◽  
Xin Nie ◽  
Dan Zhu ◽  
Mu-Xuan Tao
Author(s):  
He Zhao ◽  
Xin Nie ◽  
Dan Zhu ◽  
Mu-Xuan Tao

<p>Nowadays, reinforced concrete core wall-steel frame hybrid structural systems are widely used in mid-rise and high-rise buildings. In this type of structural system, the pulling resistant behavior of the steel beam-concrete wall joints (SBCW joints for short) plays a very important role in the seismic behavior. In this study, the pullout behavior of a new type of SBCW pinned joints with T-shaped steel connectors is tested, and the load- displacement curves and failure modes of the specimens are analyzed. Two failure modes are observed in the experiments: one is punching shear failure mode characterized by the pullout of concrete pyramid with lower strength and stiffness, and the other is web yield failure mode characterized by the yield of the web plate of the connector with higher strength and stiffness. The key factor to determine the failure mode is the embedded depth of the connector. Additionally, finite element models for the SBCW joint are established and nonlinear elastic-plastic analysis is carried out, which can predict the failure modes and pulling resistant capacity of the specimens with good accuracy. Based on the numerical model, a parameter analysis is conducted to study the influence of more factors on the capacity of the SBCW joint.</p>


Crystals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 62
Author(s):  
Xu Xu ◽  
Zeping Zhang ◽  
Wenjuan Yao

Graphene and graphene oxide (GO) usually have grain boundaries (GBs) in the process of synthesis and preparation. Here, we “attach” GBs into GO, a new molecular configuration i.e., polycrystalline graphene oxide (PGO) is proposed. This paper aims to provide an insight into the stability and mechanical properties of PGO by using the molecular dynamics method. For this purpose, the “bottom-up” multi-structure-spatial design performance of PGO and the physical mechanism associated with the spatial structure in mixed dimensions (combination of sp2 and sp3) were studied. Also, the effect of defect coupling (GBs and functional groups) on the mechanical properties was revealed. Our results demonstrate that the existence of the GBs reduces the mechanical properties of PGO and show an “induction” role during the tensile fracture process. The presence of functional groups converts in-plane sp2 carbon atoms into out-of-plane sp3 hybrid carbons, causing uneven stress distribution. Moreover, the mechanical characteristics of PGO are very sensitive to the oxygen content of functional groups, which decrease with the increase of oxygen content. The weakening degree of epoxy groups is slightly greater than that of hydroxyl groups. Finally, we find that the mechanical properties of PGO will fall to the lowest values due to the defect coupling amplification mechanism when the functional groups are distributed at GBs.


2021 ◽  
Vol 30 ◽  
pp. 263498332110061
Author(s):  
Gunyong Hwang ◽  
Dong Hyun Kim ◽  
Myungsoo Kim

This research aims to optimize the mechanical properties of woven fabric composites, especially the elastic modulus. A micromechanics model of woven fabric composites was used to obtain the mechanical properties of the fiber composite, and a genetic algorithm (GA) was employed for the optimization tool. The structure of the fabric fiber was expressed using the width, thickness, and wave pattern of the fiber strands in the woven fabric composites. In the GA, the chromosome string consisted of the thickness and width of the fill and warp strands, and the objective function was determined to maximize the elastic modulus of the composite. Numerical analysis showed that the longitudinal mechanical properties of the strands contributed significantly to the overall elastic modulus of the composites because the longitudinal property was notably larger than the transverse property. Therefore, to improve the in-plane elastic modulus, the resulting geometry of the composites possessed large volumes of related strands with large cross-sectional areas and small strand waviness. However, the numerical results of the out-of-plane elastic modulus generated large strand waviness, which contributed to the fiber alignment in the out-of-plane direction. The findings of this research are expected to be an excellent resource for the structural design of woven fabric composites.


2021 ◽  
Vol 3 (6) ◽  
Author(s):  
Seyed Ali Mirsalehi ◽  
Amir Ali Youzbashi ◽  
Amjad Sazgar

AbstractIn this study, epoxy hybrid nanocomposites reinforced by carbon fibers (CFs) were fabricated by a filament winding. To improve out-of-plane (transverse) mechanical properties, 0.5 and 1.0 Wt.% multi-walled carbon nanotubes (MWCNTs) were embedded into epoxy/CF composites. The MWCNTs were well dispersed into the epoxy resin without using any additives. The transverse mechanical properties of epoxy/MWCNT/CF hybrid nanocomposites were evaluated by the tensile test in the vertical direction to the CFs (90º tensile) and flexural tests. The fracture surfaces of composites were studied by scanning electron microscopy (SEM). The SEM observations showed that the bridging of the MWCNTs is one of the mechanisms of transverse mechanical properties enhancement in the epoxy/MWCNT/CF composites. The results of the 90º tensile test proved that the tensile strength and elongation at break of nanocomposite with 1.0 Wt.% MWCNTs improved up to 53% and 50% in comparison with epoxy/CF laminate composite, respectively. Furthermore, the flexural strength, secant modulus, and elongation of epoxy/1.0 Wt.% MWCNT/CF hybrid nanocomposite increased 15%, 7%, and 9% compared to epoxy/CF laminate composite, respectively.


2021 ◽  
Vol 881 ◽  
pp. 149-156
Author(s):  
Mochamad Teguh ◽  
Novi Rahmayanti ◽  
Zakki Rizal

Building material innovations in various interlocking concrete block masonry from local materials to withstand lateral earthquake forces is an exciting issue in masonry wall research. The block hook has an advantage in the interlocking system's invention to withstand loads in the in-plane and out-of-plane orientations commonly required by the masonry walls against earthquake forces. Reviews of the investigation of in-plane and out-of-plane masonry walls have rarely been found in previous studies. In this paper, the results of a series of experimental tests with different interlocking models in resisting the simultaneous in-plane shear and out-of-plane bending actions on concrete blocks are presented. This paper presents a research investigation of various interlocking concrete blocks' mechanical properties with different hook thicknesses. Discussion of the trends mentioned above and their implications towards interlocking concrete block mechanical properties is provided.


Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2421 ◽  
Author(s):  
Angelos Filippatos ◽  
Maik Gude

Fibre-reinforced composite structures subjected to complex loads exhibit gradual damage behaviour with the degradation of the effective mechanical properties and changes in their structural dynamic behaviour. Damage manifests itself as a spatial increase in inter-fibre failure and delamination growth, resulting in local changes in stiffness. These changes affect not only the residual strength but, more importantly, the structural dynamic behaviour. In the case of composite rotors, this can lead to catastrophic failure if an eigenfrequency coincides with the rotational speed. The description and analysis of the gradual damage behaviour of composite rotors, therefore, provide the fundamentals for a better understanding of unpredicted structural phenomena. The gradual damage behaviour of the example composite rotors and the resulting damage-dependent dynamic behaviour were experimentally investigated under propagating damage caused by a combination of out-of-plane and in-plane loads. A novel observation is the finding that a monotonic increase in damage results in a non-monotonic frequency shift of a significant number of eigenfrequencies.


2010 ◽  
Vol 168-170 ◽  
pp. 2200-2203 ◽  
Author(s):  
Shun Bo Zhao ◽  
Na Liang ◽  
Li Xin Liu ◽  
Li Sun ◽  
Su Yang

The validity of the wet-sieving concrete technique for building the reinforced composite concrete wall are demonstrated in the paper. The fine aggregate concrete made by ordinary concrete passing the sieve with square mash of 15 mm was cast for the surface layer, the recomposed concrete mixed by the residual concrete stayed on the sieve with the ordinary concrete was cast for the reinforced concrete structural wall. The mechanical properties such as the cubic and compressive strengths, the elastic modulus and the splitting and flexural tensile strengths of the fine aggregate concrete, the recomposed concrete and the ordinary concrete were tested and analyzed. The results show that the elastic modulus and splitting tensile strength of fine aggregate concrete reduce in some extent compared with that of ordinary concrete, the mechanical properties of recomposed concrete are almost the same as that of ordinary concrete.


2018 ◽  
Vol 10 (26) ◽  
pp. 22167-22173 ◽  
Author(s):  
Qing Tu ◽  
Ioannis Spanopoulos ◽  
Shiqiang Hao ◽  
Chris Wolverton ◽  
Mercouri G. Kanatzidis ◽  
...  

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