Reinforced Drapery Meshes: A Design Method Accounting for Retaining Ropes Contribution

Reinforced drapery meshes, both secured and pinned, constitute a compelling solution for rockfall risk mitigation on rock slopes facing structures and infrastructures. They consist of steel wire mesh panels combined with a systematic anchoring pattern. In secured drapery systems, the anchors are connected to each other and to the net through ropes. The system prevents both global instability of the surficial part of the slope thanks to the anchors and local instability by confining small detached fragments in delimited mesh sections. The mesh is generally designed with mechanical resistance derived from the puncturing force–displacement behavior observed during a standardized laboratory test. Despite the fact that a codified design method has not yet been defined, the mesh is generally verified without considering the presence of the ropes. In the present work, an enhanced design method is introduced that accounts for retaining ropes, with the aim of achieving a confining effect similar to the constraints adopted in laboratory tests. In addition, the rope pattern enables the consideration of portions of mesh smaller than pinned drapery systems. In the proposed method, rope elongation is limited such that failure of the mesh near the anchor plate is prevented. The proposed design assessment reveals that the presence of ropes provides possible cost reductions in the choice of the mesh type.

A Look at the Spatial Confining Effect on the Molecular Electrostatic Potential (MEP)—A Case Study of the HF and BrCN Molecules

In this theoretical study, we report on the molecular electrostatic potential (MEP) of titled molecules confined by repulsive potentials of cylindrical symmetry mimicking a topology. Our calculations show that the spatial restriction significantly changes the picture of the MEP of molecules in a quantitative and qualitative sense. In particular, the drastic changes in the MEP as a function of the strength of spatial confinement are observed for the BrCN molecule. This preliminary study is the first step in the investigation of the behavior of the MEP of molecular systems under orbital compression.

Look at the Spatial Confining Effect on the Molecular Electrostatic Potential (Mep). A Case Study of the Hf and Brcn Molecules

In this theoretical study we report on molecular electrostatic potential (MEP) of titled molecules confined by repulsive potentials of cylindrical symmetry mimicking a topology. Our calculations show that the spatial restriction significantly changes the picture of MEP of molecules in quantitative and qualitative sense. In particular, the drastic changes of MEP as a function of the strength of spatial confinement are observed for the BrCN molecule. This preliminary study is the first step in the investigations of the behavior of MEP of molecular systems under the orbital compression.

Effective flexural stiffness for reinforced concrete shear walls having confined boundary elements

In the design of reinforced concrete (RC) shear walls strength, ductility and effective stiffness of the elements must be taken into account and are important parameters in terms of structural safety. Accurate estimation of the ductility and effective stiffnesses of RC members has always been an attractive subject of study as it provides a reliable estimate of the capacity of buildings under seismic loads. In this study, RC shear wall models with different concrete strength, longitudinal and transverse reinforcement ratios were designed to investigate effective section stiffness and coefficients. The effective stiffness of the cracked section in the RC shear walls designed in different parameters were analytically obtained. Analytically investigated parameters were calculated from TBEC (2018), ACI318 (2014), ASCE/SEI41 (2017) and Eurocode8 (2004, 2005) regulations and nonlinear behaviors. The results obtained according to different design parameters were compared and examined. In the relations suggested for the effective section stiffness coefficient, the confining effect is not taken into account as in the regulations. Therefore, it means neglecting the effects of parameters such as concrete strength, confining effect and axial load levels acting on the section. This situation can lead to unrealistic results in the design and evaluation of RC elements. For this reason, determining the moment-curvature relationship in the design and evaluation of RC elements and obtaining effective section stiffness values are of great importance in order to obtain more realistic results.

The Simple Mix Design Method and Confined Behavior Analysis for Recycled Aggregate Concrete

For the environment protection and sustainable development in building construction, waste concrete can be processed into recycled aggregate to mix the recycled aggregate concrete (RAC). However, the existing mix design methods of RAC were complex, and the mechanical properties of RAC were more weakened than ordinary concrete. This paper presents a simple mix design method for RAC, including orthogonal test and single-factor test. Then, in order to study the behavior of confined RAC, this paper presents a comprehensive experimental study on the RAC filled in steel tube (RCFST) specimens and the RAC filled in GFRP tube (RCFST) specimens. The results show that the proposed mix design method can mix different stable strength grades of RAC promptly and efficiently. In addition, the steel tube and GFRP tube can provide a well confining effect on core RAC to improve the mechanical behavior of column. Moreover, the properties of core RAC in steel tube are the same as the common passive confined concrete, and the properties of core RAC in the GFRP tube are the same as the common active confined concrete. The study results can provide reference for other kinds of RAC mixtures as well as be a foundation for theoretical studies on confined RAC.

Diffusion of High-Temperature and High-Pressure CH4 Gas in SiO2 Nanochannels

Fundamental understandings of nanoconfined methane (CH4) are crucial to improving the exploitation of tight gas. In this study, diffusivity, one of the key transport properties of high-temperature and high-pressure methane gas, is examined under confinement in the silica nanochannels by using molecular dynamics simulations by employing Einstein diffusion equation. It was found that the diffusivity of nanoconfined methane is obviously anisotropic, namely, the perpendicular diffusion coefficient is lower than that in the longitudinal direction. The anisotropic diffusivity of nanoconfined methane is attributed to the restricted effect of potential interactions from the atoms of walls, which is verified by analyzing the diffusivity of methane molecules in the potential wells with Lagrangian dynamics. The diffusion coefficients of nanoconfined methane decrease with the increase of atomic potentials in the wall, which can be explained by the density distributions of methane in the nanochannels. Furthermore, we reveal the dependence of the diffusivity of nanoconfined methane on the channel height and confining effect of the wall on the diffusivity of methane molecules. The obtained results can provide a molecular insight into the transport properties of methane confined in nanospace and a theoretical guidance for the efficient extraction of tight gas.

Biomimetic caged platinum catalyst for hydrosilylation reaction with high site selectivity

Natural enzymes exhibit unparalleled selectivity due to the microenvironment around the active sites, but how to design artificial catalysts to achieve similar performance is a formidable challenge for the catalysis community. Herein, we report that a less selective platinum catalyst becomes highly active and selective for industrially relevant hydrosilylation of a broad range of substrates when a porous cage ligand is used for confinement around the catalytic active site. The catalyst is more than ten times more active than Karstedt’s catalyst while being recyclable. Properties such as size-selective catalysis and Michaelis-Menten kinetics support the proposed enzyme-like model. This biomimetic catalyst exhibits remarkable site-selectivity through the cage’s confining effect, which amplifies small steric differences into dramatic reactivity changes for similar functional groups within a molecule.

On lap splice length of lap-spliced crossties for reinforced concrete columns under cyclic loading

A lap-spliced crosstie comprises two J-shaped rebars, each with a 180° hook at one end and straight at the other end. Six large reinforced concrete columns subjected to lateral cyclic loading were tested. The results indicated the following: (1) the confining effect of horizontally lap-spliced crossties is similar to that of vertically lap-spliced crossties. (2) Splice length of the lap-spliced crossties that is smaller than the code requirement can also provide sufficient concrete confinement. (3) A method for determining required lap splice length for lap-spliced crossties is proposed. (4) The lap-spliced crosstie can considerably improve the constructability of the crossties. Furthermore, the construction quality of reinforced concrete column reinforcement and the seismic resistance capability of reinforced concrete structures can be significantly upgraded.