框架结构提升稳定性的设计及应用分析

本文深入探讨了框架结构稳定性设计及应用,涵盖理论基础、设计原则、材料选择与构造措施,以及先进技术与创新应用。文章首先指出稳定性是建筑结构安全性的基石,对延长建筑使用寿命、提升使用价值和经济效益至关重要。随后,通过分析结构力学原理、设计原则与规范、荷载分析、结构模型简化、稳定性验算与评估等方面,阐述了框架结构稳定性设计的理论基础和系统性方法。在材料选择与构造措施方面,介绍了传统与新型材料的性能对比及应用前景,强调了构造措施的精细化设计对提升稳定性的重要性。同时,探讨了预制构件与现场装配的协同优化、施工质量控制及长期维护与检修策略。此外,还介绍了数值模拟与仿真分析、智能化监测与维护、3D打印与自动化建造技术、绿色建筑与可持续发展技术等在框架结构稳定性设计中的创新应用。通过综合分析与实践案例,本文为框架结构稳定性设计提供了科学、全面、实用的指导,对于推动建筑技术发展、保障建筑安全具有重要意义。

基于拱券结构受力机理的黄土窑洞加固方法

窑洞是中国西北黄土高原上一种典型的传统民居,它的妥善保护与传承对于解决我国当前的能源、环境问题都具有重大的现实意义。既有黄土窑洞拱券顶部土体往往存在拉应力,在使用过程中,当土体含水率变化而致使土体力学性能发生较大改变时,窑洞拱顶容易发生局部坍塌,严重影响了窑洞的使用寿命,具有较大的安全隐患。结合不同结构类型的窑洞及其主要的破坏形态,并依据结构力学中的合理拱轴线理论,提出了一种基于力学原理的既有黄土窑洞加固方法。加固后的窑洞拱顶所受剪力和弯矩理论值为零,仅承受轴力,使得拱券顶部处于最佳地受力环境,拱券结构最安全。该方法合理利用拱券结构的力学原理,步骤简单、设计合理且实现方便、使用效果好、花费成本低,能简便、快速对黄土窑洞进行有效加固。

Mechanical properties and fracture mechanism of as-cast MnFeCoCuNix high-entropy alloys

MnFeCoCuNix high-entropy alloys(HEAs)with different Ni contents were fabricated by vacuum induction melting.XRD and SEM−EDS were used to analyze the phase constitution and structure,and the tensile properties of the samples were determined using a universal tensile tester.The results show that the HEAs consist of a dual-phase structure,in which FCC1 phase is rich in Fe and Co,while the FCC2 phase has high contents of Cu and Mn.As Ni content increases,the segregation of Cu decreases,accompanied by the decrease of FCC2 phase.Moreover,the tensile strength of the HEAs increases first and then decreases,and the elongation increases slightly.This is attributed to the combined effect of interface strengthening and solid solution strengthening.The in-situ stretched MnFeCoCuNi0.5 alloy shows obvious neck shrinkage during the tensile fracture process.In the initial deformation stage,the slip lines show different morphologies in the dual-phase structure.However,in the later stage,the surface slip lines become longer and denser due to the redistribution of atoms and the re-separation of the dissolved phase.

Electronic structures and thermodynamic properties of HfAl_3 in L1_2, D0_(22) and D0_(23) structures

To better understand the relative stability and bonding characteristics of the L12, D022 and D023 structures for HfAl3, the formation enthalpies, electronic structures and thermodynamics properties were investigated by first-principles calculations. The agreement of calculated equilibrium lattice parameters and formation enthalpies with experimental results indicates the reliability of this work. The order of structural stability is D023〉D022〉L12. The results of densities of states, atomic Mulliken charge and bond population support the best structural stability for D023 structure. Variations of thermodynamic properties with temperature were predicted via phonon frequencies calculation. The enthalpy, entropy, free energy of D023 structure change more quickly than those of the other two structures. The Debye temperatures of L12, D022 and D023 structures are 399, 407 and 416 K, respectively. The volume thermal expansions for HfAl3 increase exponentially at the low temperature, whereas the thermal expansion coefficients increase linearly at the high temperature.

Correlation between mixing enthalpy and structural order in liquid Mg−Si system

The mixing enthalpies and structural order in liquid Mg−Si system were investigated via ab-initio molecular dynamics at 1773 K.By calculating the transferred charges and electron density differences,the dominance of Si−Si interactions in the chemical environments around Si was demonstrated,which determined that the mixing enthalpy reached the minimum on Mg-rich side.In terms of Honeycutt and Anderson(HA)bond pairs based on the partial pair correlation functions,the attraction between Si−Si pairs and Mg atoms was revealed,and the evolution of structural order with Si content was characterized as a process of constituting frame structures by Si−Si pairs that dispersed Mg atoms.Focusing on tetrahedral order of local Si-configurations,a correlation between the mixing enthalpy and structural order was uncovered ultimately,which provided a new perspective combining the energetics with geometry to understand the liquid Mg−Si binary system.

First-principles calculation of structural and thermodynamic properties of titanium boride

The equilibrium lattice parameters, electronic structure, bulk modulus, Debye temperature, heat capacity and Gibbs energy of TiB and TiB2 were investigated using the pseudopotential plane-wave method based on density functional theory (DFT) and the improved quasi-harmonic Debye method. The results show that the total density of states (DOS) of TiB2 is mainly provided by the orbit hybridization of Ti-3d and B-2p states, and the total DOS of TiB is mainly provided by the hybrids bond of Ti-3d and B-2p below the Fermi level and Ti—Ti bond up to the Fermi level. The Ti—B hybrid bond in TiB2 is stronger than that in TiB. Finally, the enthalpy of formation at 0 K, heat capacity and Gibbs free energy of formation at various temperatures were determined. The calculated results are in excellent agreement with the available experimental data.

Connecting microscopic structure and macroscopic mechanical properties of structural materials from first-principles

Computer simulation plays a critical role in connecting microscopic structure and macroscopic mechanical properties of structural material,which is a key factor that needs to be considered in design of such kind of material.Via the quantum mechanics first-principles calculations,one can gain structure,elastic constant,energetics,and stress of selected material system,based on which one is able to predict the mechanical properties or provide useful insights for the mechanical properties of the materials.This can be done either directly or in combination with the empirical criterions.This paper reviews the recent research advances on the attempts to predict the mechanical properties of structural materials from first principles.

Understanding formation mechanism of ZnO diatomic chain and multi-shell structure using physical mechanics:Molecular dynamics and first-principle simulations

In this paper,the possibility of the monatomic chain (MC) formation for ZnO material was studied by molecular dynamics (MD) simulation.The process of MC formation and the effects of temperature,strain rate and size were studied extensively.The tensile process can be divided to be five stages and the ZnO diatomic chain (DC) can be found.The MD results show that most atoms in MC came from the original surface of ZnO nanowires (NWs).Temperature and strain rate are two important factors affecting the process,and both high temperature and low strain rate in a certain range would be beneficial to the formation of DC.Moreover,the effects of strain rate and temperature could attribute to the Arrhenius model and the energy release mechanism.Furthermore,multi-shell structure was found for the samples under tensile strain and the layer-layer distance was about 3.Our studies based on density functional theory showed that the most stable structure of ZnO DC was confirmed to be linear,and the I-V curve was also got using ATK.

Effect of rare earth elements on the structures and mechanical properties of magnesium alloys

By means of first-principles calculations,we have investigated the effects of rare earth elements (REEs) on the structures and mechanical properties of magnesium.The lattice parameters,elastic constants,bulk moduli,shear moduli,Young's moduli and anisotropic parameter of these solid solutions have been calculated and analyzed.The nearest-neighbor distance between Mg and the REEs is also analyzed to explore the correlation with the bulk moduli.The results show that the 4f-electrons and atomic radii play an important role in the strengthening process.The anomalies of the lattice parameters and mechanical properties at Eu and Yb are due to the half-filled and full-filled 4f-electron orbital states.Finally,the increase of directional bonding character near the alloying elements may account for the anisotropy and brittleness of these magnesium alloys.

A Gibbs free energy formula for protein folding derived from quantum statistics

The fundamental law for protein folding is the thermodynamic principle.The amino acid sequence of a protein determines its native structure and the native structure has the minimum Gibbs free energy.Lacking of a Gibbs free energy formula is the reason that all ab initio protein structure prediction only empirical and various empirical energy surfaces or landscapes are introduced to fill the gap.We make a quantum mechanics derivation of the Gibbs free energy formula G(X)using quantum statistics for a single conformation X.For simplicity,only monomeric self folding globular proteins are considered.