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Set-back modification represents a dependable method to reducing the wind effects on high-rise buildings, but the flow mechanism and aerodynamic responses of set-back tall buildings have not been explored systematically. Using the square building as the benchmark model, six set-back building models with varying steps and sizes were chosen for numerical simulation in this study. The results of mean wind pressure and local wind force distribution, power spectral densities of base moment, flow field, and structural response of the proposed building models are compared and analysed using the Large Eddy Simulation (LES) technique. The results demonstrate that the aerodynamic performance of set-back tall buildings dramatically improved, with the actual optimization in the cross-wind direction being more significant. Generally, a single set-back measure can enhance the aerodynamic performance of high-rise buildings more effectively than a double set-back measure. The outcome of this study provides an aerodynamic design guide for set-back tall buildings. [ABSTRACT FROM AUTHOR]

The durability degradation of reinforced concrete was mainly caused by chloride ingress. Former studies have used component parameters of concrete to predict chloride diffusion by machine learning (ML), but the relationship between microstructure and macroparameter of concrete need to be further clarified. In this study, multi-layer perceptron (MLP) and support vector machine (SVM) were used to establish the prediction model for chloride diffusion coefficient in concrete, especially for the solid waste concrete. A database of concrete pore parameters and chloride diffusion coefficients was generated by the algorithm based on the Gaussian mixture model (GMM-VSG). It is shown that both MLP and SVM could make good predictions, in which the data using the normalization preprocessing method was more suitable for the MLP model, and the data using the standardization preprocessing method was more adapted to the SVM model. [ABSTRACT FROM AUTHOR]

Perforated cold-formed steel (PCFS) beams are regarded as an economical option for steel construction industry owing to its various advantages. They can provide access for the facilities like electric wires and pipelines to penetrate the web so that extra building space could be saved. However, the web openings might change the web stress distribution as well as reduce the cross-sectional properties, which make the PCFS beams more susceptible to buckling and may have effect on their load-bearing capacity. In this paper, a simplified spring model was proposed based on the use of energy method, to predict the critical moment of lateral-torsional buckling of PCFS channel beams with circular holes in web subject to pure bending. The effect of hole sizes and lateral restraint at the tension flange was examined by using the derived analytical solution. In addition, eigenvalue buckling analysis was conducted by using finite-element package ANSYS to validate the accuracy of the proposed analytical model. The results demonstrated that the proposed analytical solution was reliable and the critical moment predicted can be used for the extension of DSM formulae for the design of PCFS beams when considering the failure caused by lateral-torsional buckling of the beams. [ABSTRACT FROM AUTHOR]

Perforated cold-formed steel (PCFS) beams are increasingly used in constructional industry and become popular due to their advantages and economic benefit. Apart from the light weight, the openings in PCFS beams can also be used for services such as pipe utilities to release more building space. However, beams with web perforations may collapse as the result of web-distortional buckling or flange/web distortional buckling due to the web weakness caused by perforations. In this paper a study on the flange/web distortional buckling of PCFS beams is presented. An analytical solution to determine the critical stress of flange/web distortional buckling of PCFS beams is derived by using energy method. To demonstrate the analytical solution, finite element analysis is also carried out. The finite element analysis results show that the analytical solution provided can give good and reliable prediction for the flange/web distortional buckling of PCFS beams. [ABSTRACT FROM AUTHOR]

In this paper, the axial compression buckling problem of castellated columns about the major axis when exposed to a fire is investigated. An analytical formula for calculating the critical buckling load of castellated columns is derived, which considers not only the shear deformation effect of web openings but also the non-uniform cross-section temperature distribution due to non-symmetric fire exposure. The results show that for the same average temperature, the critical buckling load of a castellated column with non-uniform temperature distribution is smaller than that of a castellated column with uniform temperature distribution. The web shear effect caused due to web openings can significantly reduce the critical buckling load of the castellated column, particularly for the columns with shorter lengths or wider flanges. However, the change of the shear effect on the critical load with different temperature distributions is very small and can be generally ignored. [ABSTRACT FROM AUTHOR]

Abstract Glass powder (GP) is a solid waste with increasing reserves. GP can be used as a supplementary cementitious material (SCM) to produce concrete in order to effectively save resources and solve environmental pollution problems. The effect of GP to replace cement partially by weight on the compressive strength, elastic modulus and creep of concrete has experimentally been studied, and the internal microstructure is also determined by mercury intrusion porosimetry, scanning electron microscope and nanoindentation techniques. The results show that the use of GP reduces the compressive strengths and elastic modulus at the early ages, but the use of GP content less than 20% increases the compressive strengths and elastic modulus at the later ages. The use of GP content less than 20% can obviously reduce the creep and the use of 20% GP content seems to be the best in terms of the reduction of the creep. The use of GP with the appropriate content can effectively improve the internal microstructure of concrete and increase the content of high density calcium silicate hydrate at the later ages which is helpful in reducing the creep. This may be attributed to the pozzolanic reaction and microfiller effect of GP. [ABSTRACT FROM AUTHOR]

Chemical investigation of the acid hydrolysate of Cynanchum bungei roots led to the isolation of eleven undescribed steroids, namely cynbungenins A-K (1-11), and seven previously described analogues (12-18). The complete structures of these compounds were elucidated using the comprehensive spectroscopic analyses and reference data. Structurally, compounds 1 and 2 represent the first example of androstane-type steroids found in the Cynanchum plants, and compounds 3-6 and 12 are characterized as pregnane-type steroids with a rare 8,14-seco-steroid core. In the cytotoxic activity assay, compound 16 displayed the strongest cytotoxic effect against MCF-7, HCT-116, HeLa, and HepG2 cancer cell lines, with IC 50 values of 9.98-16.42 μM, and further research indicated that it induced both apoptosis and cell cycle arrest in the G0/G1 phase in a dose-dependent manner toward HepG2 cells., Competing Interests: Declaration of competing interest All authors declare that No conflict of interest exists., (Copyright © 2024 Elsevier Ltd. All rights reserved.)