早拆模板在施工中应用的工艺原理分析

早拆模板是建筑施工技术的重要组成部分,通过将早拆模板应用在建筑施工活动中可降低施工成本,提高建筑工程建设水平.为强化早拆模板应用效果,施工单位需要重点研究早拆模板的工艺原理,合理地规范早拆模板应用工作,切实发挥早拆模板在建筑工程中的价值.     

可调高度早拆模板支撑头

可调高度早拆模板支撑头专利号：９５２０３７７５．０该专利作为建筑施工中平台支撑的一种支撑早拆装置。在不拆除支撑的情况下，可将龙骨和模板先期拆除，从而加快模板周转，减少模板投入，降低企业成本。该专利与现有同类技术产品的区别在于：活动托翼设有可调高度内螺...     

运用新型模板体系促进科技兴企

由于现代砼建筑设计的日益多样化和复杂化,以及构件的巨型化和异型化,模板工程对整个砼工程的成本和工期都有重大的关系。由于目前高层建筑中更多地采用了整体性能好的现浇砼,而高层及超高层中的标准层增高,这样一方面促进了模板新技术的采用。另一方面也给模板的专业化和工业化施工带来更大的可能,新型模板体系及其综合利用技术成为节约工程造价和缩短工期的重要途径之一。本文着重介绍了模板早拆体系的应用。     

一次成型树脂饰面混凝土模板及其饰面树脂MPF-984的开发

随着建筑业的发展，木制模板已逐渐淘汰。胶合板模板以幅面宽、强度高、厚度均匀、脱模容易而逐渐显示其优越性。随着建筑模板的年需求量逐年增加，胶合板模板的生产也因此有了飞速的发展。在现浇混凝土施工中，模板要反复地支、拆，因此对模板有耐久性要求。在使用过程中...     

竹模板在工程施工中的应用

本文作者对竹模板在钢筋砼浇注施工中的应用及竹胶模板的选用,框架柱组合定型模板,墙体钢竹组拼式大模板,楼板竹模板快拆体系,以及使用中注意的几个问题,均作了较详细的阐述。     

一种新型钻模装置设计

针对回转类零件圆周方向孔加工划线难的问题,设计一种带钻套的新型钻模装置。该装置采用分离式钻模板,可满足不同精度要求孔的加工,且装拆方便。     

全现浇外墙木模板加固体系施工技术研究

铝合金模板全现浇外墙的加固体系相对完善，成型质量良好，但是相比铝合金模板，全现浇外墙采用木模板加固体系尚不成熟。依托保利锦上雅苑项目，首先介绍了木模板的施工工艺流程和施工中的注意事项；其次通过对全现浇外墙中木模板不同的加固体系进行研究，木模拆模后，利用统计法从混凝土成型后的指标特证、混凝土成型的质量水平和观感效果进行了对比分析，选择出较好的加固体系，为未来项目中类似的木模板加固体系提供参考。研究结果表明：当背楞立放时，混凝土成型后的3大指标合格率较高，混凝土成型的质量水平和效果较好，不易发生胀模现象，比较经济实惠。     

竹胶合板——混凝土模板的构造与应用的研究

竹胶合板是我国最近开发的一种轻质、高强的代木材料。它的种类很多,其中用经纬编席坯板作胶合板的奇数间板,以帘吊内簧坯板作填层组合热压而成的毛竹经帘交压层积板,可以制作混凝土工程面板,以代替木材面板、钢面板以及其他材质面板。它既可与木材、钢材、工程塑料组成多种规格的模板体系;也可制成全竹胶普通模板。竹胶模板适应各种类型建筑工程的施工使用,安全轻便,装拆劳动强度小、工效高,施工经济效益好。     

模板工程对施工成本的影响

本文介绍了模板在建筑中工程在使用中的方法。以及等节拍,小流水段施工,早期拆模,在施工中取得的良好经济效益。     

新型的刨花板家具角接合方式

新型的刨花板家具角接合方式谭海彦，韩春雷，张晓峰，蔡力平常规的刨花板家具采用两种连接方式：可拆式家具采用连接件连接，不可拆式家具采用圆榫连接。厨房家具由于需具有相当的承载能力和防水性能，所以一般采用圆榫进行不可拆连接。然而，就刨花板材料而言，用圆榫连...     

谈中小桥采用后张法16m预应力空心板的施工问题

本文阐述了中小桥上部结构采用后张法１６ｍ预应力空心板的施工时应注意的问题，如预应力空心板的预制中底模的施工；侧模、蕊模；砼的要求；浇筑空心板的具体步骤。     

Finite element analysis of bending stiffness for cross-laminated timber with varying board width

ABSTRACT

Cross laminated timber (CLT) is a wood panelling building system that is used in construction, e.g. for floors, walls and beams. Because of the increased use of CLT, it is important to have accurate simulation models. CLT systems are simulated with one-dimensional and two-dimensional (2D) methods because they are fast and deliver practical results. However, because non-edge-glued panels cannot be modelled under 2D, these results may differ from more accurate calculations in three dimensions (3D). In this investigation, CLT panels with different width-to-thickness ratios for the boards have been simulated using the finite element method. The size of the CLT-panels was 3.0 m × 3.9 m and they had three and five laminate layers oriented 0°–90°–0° and 0°–90°–0°–90°–0°. The thicknesses of the boards were 33.33, 40.0, and 46.5?mm. The CLT panel deformation was compared by using a distributed out-of-plane load. Results showed that panels with narrow boards were less stiff than wide boards for the four-sided support setup. The results also showed that 2D models underestimate the displacement when compared to 3D models. By adjusting the stiffness factor k88, the 2D model displacement became more comparable to the 3D model.     

浅谈林区建筑管道施工测量

本文介绍了林区建筑管道的施工测量,测量前的准备工作;开槽施工,槽口放线,埋设坡度板,放样坡度钉,顶管施工,设置中线桩,设置中心钉和水准点等。     

砖混结构教学楼夹板墙的设计与施工

本文论述了砖混结构教学楼设计与施工方法，特别阐述了夹板墙的设计原理及施工应采取的措施，可供同类房屋加固改造工程参考。     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.     

Predicting the Stiffness of Sawn Products by X-ray Scanning of Norway Spruce Saw Logs

The aim of the study was to investigate the possibility of strength grading Norway spruce [Picea abies (L.) Karst.] saw logs on the basis of simulated X-ray LogScanner measurements and to evaluate the potential accuracy of X-ray LogScanner measurements of green heartwood density and percentage of heartwood. The study was based on 272 logs for strength grading and 29 logs for measurements of green heartwood density and percentage of heartwood. The logs were scanned using computed tomography (CT). After sawing, the modulus of elasticity (MOE) of the centre boards was measured using a strength-grading machine. The CT images were used for simulations of an X-ray LogScanner, resulting in simulated measurements of different variables such as diameter, taper, percentage of heartwood, density and density variations. Multivariate models for prediction of MOE were then calibrated using partial least squares (PLS) regression. The MOE of a log was defined as the mean value of the MOE of the two centre boards. The study showed that the simulated X-ray LogScanner measured the percentage of heartwood and green heartwood density with relatively high accuracy (R ² = 0.94 and R ² = 0.73, respectively, after removing two outliers) and that these and other variables measured by the simulated X-ray LogScanner could be used to predict the stiffness of the centre boards. These predictions were used to sort the logs according to the predicted MOE. When sorting out 50% of the logs (''high-strength'' logs), the percentage of C30 boards increased from 73% (all logs in the study) to 100% (only ''high-strength'' logs). The rest of the logs could then be divided into two groups, one of them with 100% C24 and C30 boards.     

Sound absorption capability and mechanical properties of a composite rice hull and sawdust board

Rice hull–sawdust composite boards were manufactured for sound-absorbing boards in construction. The manufacturing parameters were target density (400, 500, 600, and 700?kg/m³) and rice hull content as percent weight of rice hull/sawdust/phenol resin (10/80/10, 20/70/10, 30/60/10, and 40/50/10). Commercial gypsum board and fiberboard were also used as comparative sound-absorbing materials. The average modulus of rupture (MOR) of the board with a density of 700?kg/m³ and rice hull mixing ratio of 10% was 8.6?MPa, and that of the board with a 400?kg/m³ board density and a rice hull mixing ratio of 40% was 2.2?MPa. The MOR increased with increasing board density or decreasing rice hull mixing ratio. The sound absorption coefficients of some boards (400?kg/m³ and 10%, 500?kg/m³ and 30%, and 500?kg/m³ and 40%) were better than those of the commercial 11-mm-thick gypsum board. Thus, it is concluded that rice hull–sawdust composite boards may be implemented as sound-absorbing barriers in construction due to their high sound absorption coefficients.     

Strength,decay and termite resistance of oriented kenaf fiberboards

The development of oriented fiberboards made from kenaf (Hibiscus cannabinus L.) and their suitability as a construction material has been investigated. Three different types of boards consisting of five layers with individual orientations were prepared using a combination of low molecular weight and high molecular weight phenol-formaldehyde (PF) resin for impregnation and adhesion purposes. Additional boards with the same structure were prepared using high molecular weight PF resin only. The mechanical properties of the boards have been examined as well as their resistance against fungal decay and termite attack. All kenaf fiberboards showed elevated mechanical properties compared with medium-density fiberboard made from wood fibers, and showed increased decay and termite resistance. Differences in the decay and termite resistance between the board types were caused by the presence of the low molecular weight PF resin for the impregnation of the fibers. No significant difference was found for the mechanical properties. The effect of the PF resin for impregnation was much clearer in fungal decay resistance than for termite resistance; however, fiber orientation had no effect on both decay and termite resistance of the specimens.     

Effect of collapse on fitted diffusion coefficients for Victorian ash eucalypts

Wet cores, recently observed in highly collapsed boards towards the end of pre-drying, suggest that a previously unobserved relationship between collapse and the rate of internal moisture diffusion may exist. In this study, a drying model has been used to fit the diffusion coefficient and other model parameters to the drying data from the earlier study. The model parameters were fitted to six sub-samples from 20 sample boards (a total of 120 sub-samples). The model was only fitted to the drying data from green to 50% average moisture content. An inter-relationship between basic density, collapse and the fitted diffusion coefficient was established and discussed. It is suggested that the effect of collapse on diffusion coefficient could be the result of two different mechanisms.     

Properties of strand boards with uniform and conventional vertical density profiles

Randomly oriented strand boards with both uniform and conventional vertical density profiles (VDP) were manufactured, and their properties were evaluated and compared. The bending modulus of elasticity (MOE) of conventional strand boards was predicted using the laminated beam theory and the MOE-density regression equation from the uniform strand boards. The results showed that the predicted MOE of conventional strand boards was close to the measured MOE with a difference of less than 10%. The internal bond strength values of uniform strand boards were found to be higher than conventional strand boards while no significant difference was found in water-related properties. Compared with uniform strand boards, MOE values of conventional strand boards were improved only at higher density level. About 10% of improvement in MOE can be obtained for the strand boards investigated by manipulating the VDP. Steeper VDPs were predicted to be required for thinner boards than for thick boards in order to achieve the same improvement in MOE.