120m 高钢筋混凝土烟囱爆破拆除

介绍了用定向控制爆破方法拆除吉化电石厂120m钢筋混凝土烟囱的经验。针对该烟囱下部有1个门和3个窗户的特殊结构,选择倒梯形爆破切口,以增强预留支撑面的强度。为防止烟囱落地产生震动和前冲,在倒塌的前方设置了减震带和阻冲挡土墙。文中同时还阐述了参数的选择与计算,以及爆破效果。文中总结的四点经验值得借鉴。     

混凝土面板堆石坝坝体过水保护

天生桥一级水电站混凝土面板堆石坝堆石填筑量大，在大坝填筑施工的第一个汛期，坝体内预留底宽１２０ｍ、边坡１：１．４的梯形泄槽，该泄槽与导流隧洞联合运行承担１９９６年汛期泄洪任务。泄槽过流按３０年一遇洪水标准加以保护，选用直径大于２０ｃｍ的干砌块石护坡，其表面覆盖铁网，并用钢筋框格固定，泄槽重要部位采用钢筋铁丝笼充填块石加以保护。泄槽过流后，抽水检查结果表明，过流保护面无任何冲刷破坏，达到了安全渡汛的     

钢筋混凝土厚板裂缝间距的分析模型

建立一个简单、实用的新模型预测正交钢筋混凝土板的开裂行为。新的模型能解释箍筋对开裂行为的影响,同时也考虑了影响钢筋混凝土构件开裂行为的主要参数,包括混凝土抗拉强度、配筋率、钢筋直径、间距。采用平衡和协调方程,对钢筋混凝土单元进行研究,以求出钢筋和混凝土的平均应力。对本文试验研究结果以及涉及不同结构单元、荷载条件的已有研究成果进行一系列验证比较可知。所提出的裂缝间距模型能够预测不同荷载阶段的裂缝宽度值。在所研究案例中,试验值与模型预测值吻合较好。     

Properties of hybrid fibre reinforced shell for investment casting

In order to improve the properties of silicon sol shell for investment casting process, a varying content of hybrid fibres (aluminium silicate and polypropylene) was introduced into slurry for preparation of fibre-reinforced shell in the present work. The bending strength, self-load deformation at elevated temperature, and the permeability of fibre-reinforced shell specimens were investigated and the fracture surfaces of shell specimens were observed by SEM. The results show that the bending strength of green shell increases with content of fibres in it. The maximum bending strength of 4.96 MPa was obtained in the fired shell with 0.6 wt% hybrid fibres addition. The high temperature self-loaded deformation of specimens of shell reinforced with a hybrid fibre addition above 0.6 wt% is higher than that of the unreinforced. However, the shell with a hybrid fibre addition up to 0.4 wt% exhibits the lower self-loaded deformation at high temperature compared to the unreinforced. It is also found that the permeability of shell specimens can be improved by hybrid fibres addition. Based on the fracture surfaces observation using a scanning electron microscope (SEM), the failure mode of the green shell reinforced with hybrid fibres is identified as fibre rupturing from the substrate of shell specimens, and/ or debonding from adhesive film surrounding it in shell. Even though the specimens of shell being fired at 900 °C for 2 h, the same failure features also exist in the fracture surfaces of specimens. This indicates that the specimens of shell can still be reinforced with aluminium silica fibres (residue of hybrid fibres) for their interpenetrating fibres network structure although go through firing.     

Effective monitoring of corrosion in reinforcing steel in concrete constructions by a multifunctional sensor

A novel multifunctional sensor is developed for in situ and non-destructive monitoring of the corrosion current and open circuit potential of reinforcing steel, as well as the pH and Cl⁻ concentration of concrete. The pH and Cl⁻ sensors show good responses to the pH and Cl⁻ concentration of concrete pore solutions, respectively, and are able to monitor both the carbonization process of concrete and the ingress of Cl⁻ in concrete. Combined with measurements of the corrosion potential and corrosion current density, as well as the EIS spectra of reinforcing steel in concrete, this study demonstrates that the pH and the Cl⁻ concentration of concrete are two of the most crucial factors that determine the corrosion of reinforcing steel in concrete. The corrosion tendency and corrosion rate of reinforcing steel largely depend on the chemical environment in the concrete. The multifunctional sensor is a powerful tool for in situ monitoring corrosion of steel in concrete, and provides accurate details of the chemical condition of the concrete pore solution and the corrosion status of the reinforcing steel in concrete. These are essential for corrosion predictions and service life evaluations of concrete constructions.     

氧化膜强化技术在钽电容器生产中的应用

采用氧化膜强化技术在钽阳极体外表面形成抗机械应力的强化氧化膜,并模拟钽电容器回流焊过程,研究回流焊前后钽电容器漏电流变化以及对击穿电压(BDV)的影响。试验结果显示:在回流焊安装前后,应用氧化膜强化技术的电容器漏电流增幅小于普通产品14%;耐BDV比普通产品高6 V。     

80m高钢筋砼烟囱的爆破拆除

论述了控制爆破拆除钢筋砼烟囱的方案设计与力学计算、爆破参数确定、施工方法、安全防护措施、震动监测和爆破效果.     

有载调压变压器直流电阻异常分析

通过对一起有载调压变压器直流电阻不平衡故障分析，总结经验，提出解决措施以便更好地做好有载调压变压器的检修工作。     

基于pushover方法分析的受腐蚀钢筋混凝土柱抗震性能评价

根据先前对受腐蚀钢筋混凝土偏心受压构件低周反复性能的试验研究结果,提出了构件滞回耗能与钢筋锈蚀率的关系,结合先前提出的受腐蚀构件的恢复力骨架曲线的计算模型,采用pushover方法对地震作用下的受腐蚀钢筋混凝土构件的变形性能进行了分析,得到钢筋锈蚀率与结构弹塑性变形的关系。分析结果表明,随着钢筋锈蚀率的增大,钢筋混凝土构件的变形呈非线性增大,地震强度越大,结构变形随钢筋锈蚀率增加的越快。在规定的变形要求下,随钢筋锈蚀率的增大,结构可承受的地震作用呈非线性降低,钢筋锈蚀越严重,构件在相同变形下承受地震作用的能力越弱。     

Influence of curvature geometry of laminated FRP composite panels on delamination damage in adhesively bonded lap shear joints

Three dimensional non-linear finite element analyses of Lap Shear Joints (LSJs) made with curved laminated FRP composite panels having pre-existing delaminations between the first and second plies of the strap adherend have been carried out using contact and Multi-Point Constraint elements (MPC). Progressive growth of delamination has been simulated by sequential release of the MPC elements. Strain Energy Release Rate (SERR), being an indicative parameter has been computed using Virtual Crack Closure Technique (VCCT) for assessing the growth and propagation of the delamination damage fronts. The inter-laminar stresses and the SERRs at the two fronts of the pre-embedded delamination are found to be significantly influenced by the delamination size. The three individual modes of SERR on the two delamination fronts are found to be much different from each other, indicating dissimilar rates of propagation. The curvature geometry of adherends significantly influences the SERR values. It is seen that decrease of radius of curvature of adherend panels, keeping their widths unchanged, increases the SERR values. Flatter FRP composite adherends have superior resistance to delamination damage propagation as compared to LSJs made with curved composite laminated panels.