工厂化制作的新型叠合自保温节能墙体

在我国,建筑能耗连同围护结构材料生产能耗占到全国能源消耗总量的27.6%,并将随着人民生活水平的提高逐步增加到33%以上。新建建筑从建造到使用,维护结构占整个建筑能耗中比重最大,其中外墙能耗又是建筑耗能的主要部位。本文介绍一种新型叠合自保温节能墙体工业化技术,该叠合节能墙体实现了墙体在工厂连续制作,在施工现场拼装和现浇混凝土的特点,能够推进我国建筑工业化、节能环保和低能耗发展。     

基于叠合板预制式电缆沟在电力施工中的应用

基于叠合板的预制式电缆沟从施工工艺、产品质量、成品质量控制、安全措施、节能环保等方面综合考虑,是一种在以往全预制钢筋混凝土电缆沟结构上创新性采用装配式叠合板的新型施工方式。预制式电缆沟定尺分段由混凝土实心底板和叠合板空心侧壁组件拼接而成,灌浆成型。组件单体规格统一,便于批量规模化生产,重量较轻,便于运输、安装。这种施工方式的优势在变电站新建或改扩建项目的应用中尤为明显,具有建设周期短、装配性好、节能环保等优点。     

桁架钢筋叠合板设计研究

桁架钢筋叠合板在脱模、堆垛、运输、施工安装各个阶段都有可能出现裂缝,一旦开裂,将对建筑物的楼面结构造成安全隐患和一定的经济损失,桁架钢筋叠合板的设计研究有着重大意义.研究对象叠合板尺寸为3 600 mm×2 400 mm×60 mm,控制桁架钢筋种类及板底配筋面积,针对四吊点叠合板进行分析,通过力学模型简化,结合相关力...     

控制爆破拆除钢筋混凝土大桥

通过对薄壁构件扭转受力分析，探讨了微差爆破技术在钢筋混凝土桥梁拆除中的作用，并结合工程给出了钢筋混凝土薄壁梁腹板结构大桥控爆拆除的设计方法。     

小水电站钢筋混凝土压力管道的现浇施工

商州市二级电站压力管道为钢筋混凝土管道，内径２ｍ，包角１３５°，管壁厚分上中下三段不同厚度，我们采用装配式模板现场浇筑，钢筋混凝土压力管道施工质量良好，各项指标均达到了设计要求。     

控制异丁烯叠合反应催化剂床层温升的探讨

通过分析对异丁烯叠合反应器温升进行有效控制的方法,得出:①固定床外循环对原料适应性强、反应器结构简单、便于操作,但当以反应产物或剩余C4为循环物料时存在副产物含量高的问题;②列管固定床可将反应温度控制在较适宜的范围内,副反应产物少,但反应器结构较复杂、催化剂装填要求严格、列管内存在"热点";③新型热管反应器可快速移出反...     

一种快速移除反应热的异丁烯叠合工艺及优化措施

在异丁烯选择性叠合工艺中,如何有效地控制反应温升、降低多聚物生成、减少设备和操作费用等是值得研究和探讨的问题.因此,有针对性地提出一种快速移除反应热的异丁烯叠合工艺及其优化措施,主要包括:①快速移除反应热,即将碳四原料分为两部分,分别进入一级反应器的管程、壳程;管程碳四在催化剂作用下发生叠合反应,反应热被壳程碳四气化所...     

层燃锅炉应用滚动炉排的节能分析

阐述滚动炉排的工作原理,并与链条炉排、往复炉排等其他层燃炉排在节能等方面进行对比分析．     

A multifunctional heat pipe sandwich panel structure

A multifunctional sandwich panel combining efficient structural load support and thermal management characteristics has been designed and experimentally assessed. The concept is based upon a truncated, square honeycomb sandwich structure. In closed cell honeycomb structures, the transport of heat from one face to the other occurs by a combination of conduction through the webs and convection/radiation within the cells. Here, much more effective heat transport is achieved by multifunctionally utilizing the core as a heat pipe sandwich panel. Its interior consists of a 6061 aluminum truncated-square honeycomb core covered with a stochastic open-cell nickel foam wick. An electroless nickel plating barrier layer inhibited the chemical reaction between the deionized water working fluid and the aluminum structure, retarding the generation of non-condensable hydrogen gas. A thermodynamic model was used to guide the design of the heat pipe sandwich panel. We describe the results of a series of experiments that validate the operational principle of the multifunctional heat pipe sandwich panel and characterize its transient response to an intense localized heat source. The systems measured thermal response to a localized heat source agrees well with that predicted by a finite difference method model used to predict the thermal response.     

Thermomechanical wrinkling and strength of sandwich panels with nanoscale or microscale randomly reinforced core

Abstract

Wrinkling represents one of the failure modes in sandwich structures, although in practical designs the loss of strength and global buckling often occur at lower compressive loads. However, the properties of both polymeric matrix in the facings as well as the polymeric core degrade under an elevated temperature. As a consequence, wrinkling that does not present a problem at the room temperature may become a dominant mode of failure at elevated temperatures. In this article, we suggest that a reinforcement of the core material with stiff random nanoscale or microscale reinforcements may alleviate wrinkling. The solution accounts for the thermal loading history and the effect of temperature on the stiffness of the materials of the core and facings. While nano or microscale reinforcements increase the capacity of the structure to resist wrinkling, the strength of the core may be compromised due to the presence of such inclusions in the core material. Accordingly, the residual stresses in the reinforced core are evaluated using a finite-element method and accounting for the effect of temperature on the properties and stresses. It is demonstrated that both wrinkling and the core strength analyses should account for the effect of temperature on the material properties.     

山口水电站钢筋混凝土压力支管道施工技术

新疆哈巴河县山口水电站在 4条钢筋混凝土压力支管混凝土施工中采取了新技术、新工艺 ,很好地克服了因压力支管管径较大 ,场地限制而带来的施工中的难题 ,保证了压力支管混凝土工程质量     

杨凌水电站钢筋混凝土压力管道裂缝成因分析

杨凌水电站有 3条钢筋混凝土压力管道 ,在管道施工完成后 ,管道出现了部分裂缝 ,从各方面对裂缝成因进行了分析 ,认为管道裂缝由温度应力引起。     

Design change of frame structure to enhance structural reliability

A method of design change aimed at the enhancement of structural reliability is formulated. The perturbation-based stochastic finite element method is employed to evaluate the reliability index of the advanced first-order second-moment method. The enhancement of the reliability index is devised by means of the minimal design change from a baseline design, while the shift of the reliability index is incorporated in terms of an equality constraint condition. The validity of the proposed method is verified by the numerical example of a two-storeyed portal frame with uncertain Young's modulus, for which the moment of inertia of the frame members is taken as design variables.     

Estimation for probabilistic distribution of residual strength of sandwich structure with impact-induced damage

A new approach was developed to estimate the probabilistic distribution of the residual strength of honeycomb sandwich structures subjected to impact-induced damage. The model was derived from the assumption that the residual strength is a function of the static strength of the unimpacted sandwich structures and the impact damage of the impacted structures. The probabilistic distribution of the residual strength was calculated from the probabilistic properties (mean and variance) of the strength of the unimpacted laminates and the impact damage at a given impact energy. The model was experimentally verified by using an experimental program for a Nomex^® honeycomb core sandwich structure. The experimental program included a series of impact and three-point flexural tests to generate the residual strength of a sandwich structure. Theoretical predictions on the probabilistic distribution were in conformance with the experimental results.     

Thermal buckling analysis of FGM sandwich truncated conical shells reinforced by FGM stiffeners resting on elastic foundations using FSDT

This work presents an analytical approach to investigate the mechanical and thermal buckling of functionally graded materials sandwich truncated conical shells resting on Pasternak elastic foundations, subjected to thermal load and axial compressive load. Shells are reinforced by closely spaced stringers and rings, in which the material properties of shells and stiffeners are graded in the thickness direction following a general sigmoid law distribution and a general power law distribution. Four models of coated shell-stiffener arrangements are investigated. The change of spacing between stringers in the meridional direction also is taken into account. Two cases on uniform temperature rise and linear temperature distribution through the thickness of shell are considered. Using the first-order shear deformation theory, Lekhnitskii smeared stiffener technique and the adjacent equilibrium criterion, the linearization stability equations have been established. Approximate solution satisfies simply supported boundary conditions and Galerkin method is applied to obtain closed-form expression for determining the critical compression buckling load and thermal buckling load in cases uniform temperature rise and linear temperature distribution across the shell thickness. The effects of temperature, foundation, core layer, coating layer, stiffeners, material properties, dimensional parameters and semi-vertex angle on buckling behaviors of shell are shown.     

A new design of metal supported micro-tubular solid oxide fuel cell with sandwich structure

Micro-tubular solid oxide fuel cell (MT-SOFC) is considered as a promising choice for portable applications. In this work, we developed a novel metal supported MT-SOFC with porous 430 stainless steel support| 430 stainless steel-SSZ| SSZ| porous SSZ sandwich structure by dip coating and one-step co-sintering technology. The metal supported MT-SOFC showed good connection between each function layer and exhibited a significant maximum power density of 271 mW cm^?2 at 800 °C. Although the power density showed about 19.6% off after 14 thermal cycles between 600 °C and 800 °C, and about 5% per 100 h degradation rate during the 200 h long-term stability test at 700 °C and 0.7 V, the structure of the single cell could be maintained well and no crack and Sr diffusion was observed. As the result, the ohmic resistance of the cell kept unchanged during the thermal cycling and long-term test. The relatively fast degradation was attributed to the Ni and LSM particles coarsening and agglomeration, which will be improved in the further work. This work presented a low-cost and simple way to fabricate the metal supported MT-SOFCs with good electrochemical performance.     

Thermal response of a flat heat pipe sandwich structure to a localized heat flux

The temperature distribution across a flat heat pipe sandwich structure, subjected to an intense localized thermal flux has been investigated both experimentally and computationally. The aluminum sandwich structure consisted of a pair of aluminum alloy face sheets, a truncated square honeycomb (cruciform) core, a nickel metal foam wick and distilled water as the working fluid. Heat was applied via a propane torch to the evaporator side of the flat heat pipe, while the condenser side was cooled via natural convective and radiative heat transfer. A novel method was developed to estimate experimentally, the heat flux distribution of the torch on the evaporator side. This heat flux distribution was modeled using a probability function and validated against the experimental data. Applying the estimated heat flux distribution as the surface boundary condition, a finite volume analysis was performed for the wall, wick and vapor core regions of the flat heat pipe to obtain the field variables in these domains. The results were found to agree well with the experimental data indicating the thermal spreading effect of the flat heat pipe.     

Failure of reinforced concrete and tuff stone masonry buildings as consequence of hydrogen pipeline explosions

Pipelines are the most efficient method of transporting large quantities of hydrogen, and the low volumetric energy density of gaseous hydrogen requires that the gas must be compressed to extremely high pressure to be used as a transport fuel. The failure of high pressure hydrogen gas pipelines and subsequent explosion may induce heavy damage to buildings. In this paper, such an issue is addressed for existing reinforced concrete framed buildings and tuff stone masonry buildings. Physical features such as the gas jet release process, flammable cloud size, blast generation and propagation, and explosion effects on structural components of buildings are considered and evaluated through the SLAB integral model, Multi-Energy Method and pressure‒impulse diagrams. Damage to both types of structural components was evaluated and the maximum distance of blast damage was derived in several environmental conditions, contributing to land-use planning and performance-based design/assessment of pipelines and buildings.