纤维增强覆面木基墙板抗震性能试验研究#br#

通过2片不带墙骨柱、1片带墙骨柱纤维增强覆面木基墙板的低周往复试验,研究了此类玻璃纤维与胶凝材料结合作为覆面层的木基墙板的破坏形态、滞回特性、承载力、变形能力等抗震性能。试验结果表明：墙板的破坏形态为压弯破坏,墙板两端根部出现水平裂缝和斜裂缝,边框或墙骨柱与墙板结合处出现竖向裂缝,较高轴力下墙板出现裂缝早;墙板相对底座产生较大转动,修正得到的墙板滞回曲线顶点水平位移最大值约为实测顶点水平位移最大值的1/5,峰值位移角在1/528~1/445之间;试件峰值承载力较高,达到100kN,能满足抗震设防烈度不大于8度的3层及以下低层居住建筑抗震的承载力需求。     

Finish Ratings of Gypsum Wallboards

The term finish rating is used in NFPA 70, National Electrical Code (NEC)¹ to describe the required performance of finish materials installed as thermal barriers for electrical nonmetallic tubing. Finish rating data is most commonly associated with assemblies containing combustible wood framing, although the definition has also been extended to assemblies with noncombustible metal framing. To date, however, very little finish rating data has been available for common finish materials installed over metal framing. To supplement the available information, finish rating tests were conducted on identical wall sections finished with standard 1/2 gypsum wallboard from five different manufacturers, constructed with metal and wood stud framing. All 10 assemblies tested demonstrated finish ratings of 15 minutes or more.     

Inelastic behaviors of steel shear tab connections

Inelastic behaviors of shear tab connections commonly used in modern steel buildings are investigated in this work. Full‐scale steel shear tab connections with and without concrete slab physically tested by other researchers are closely simulated by non‐linear finite element (FE) method. Different nonlinear FE features (inelastic materials, surface‐based contacts and large geometric options) are included, and different solution strategies (Newton method and Explicit Dynamic method) are employed to balance computational effort and solution accuracy. The simulations extend our understandings on shear tab connections at micro levels, including stress distribution in the connection zone, movement of the neutral axis along the beam sections and normal stress distributions along steel shear tabs and concrete slabs. It is found that the shear tabs contribute to flexural strength of the beam‐to‐column connection and the elastic–plastic theory explains the observed behavior well only when concrete slab is not present. The composite steel shear tab connections have unsymmetrical behavior under negative and positive bending moments. The compressive concrete slabs significantly increase the flexural stiffness and strength of composite shear tab connections. It is also verified that the shear studs near steel columns play a key role for the composite connections. Copyright © 2013 John Wiley & Sons, Ltd.     

不同构造木、冷弯薄壁C型钢组合框架剪力墙受力性能的试验研究

由木规格材作为顶梁板和底梁板的冷弯薄壁型钢木结构是一种新型结构体系。通过对4组不同间距墙骨柱和不同间距自攻螺钉组成的冷弯薄壁型钢木框架组合剪力墙进行单向加载和反复加载试验,得到了该体系墙体的破坏形态、抗剪强度、抗侧刚度、荷载-位移等受力性能。试验结果表明：与标准构造的剪力墙相比,随着墙骨柱和边框架自攻螺钉间距的减小,剪力墙的抗剪强度和抗侧刚度提高;墙骨柱间距不同对剪力墙的影响大于自攻螺钉间距的影响。     

高强冷弯薄壁型钢墙体骨架立柱轴压性能试验及有限元分析

通过对10根550MPa高强冷弯薄壁型钢墙体骨架立柱的足尺轴压试验,得到立柱的极限承载力和破坏模式,并在试验的基础上建立墙体骨架立柱有限元分析模型。在有限元分析模型的正确性得到试验充分验证的情况下,对高强冷弯薄壁型钢墙体骨架立柱进行参数分析,分析结果表明:自攻螺钉直径的变化、采用两个螺钉连接立柱与导轨、导轨厚度和屈服强度的变化以及改变墙体骨架立柱间距均对墙体骨架立柱的轴压承载力没有显著影响;在墙体骨架两侧设置柔性拉条对立柱轴压承载力的提高很有帮助,拉条间距小于1/4柱高后承载力提高幅度不大。     

浅析PW喷油泵柱塞套双头螺柱断裂的原因

为了解决在市场上出现的柱塞套双头螺柱断裂现象 ,对双头螺柱进行强度计算、可靠性试验和断裂现象分析 ,发现断裂并非由双头螺柱本身质量缺陷或疲劳断裂引起 ,而是双头螺柱上的螺母松动引起 ;对称双头螺柱上的两个螺母松动力矩不对称是引起单边螺母松动的重要原因。通过采取增强平垫圈刚度、选择适当的拧紧力矩范围等措施 ,可以解决这个问题 ,从而有效防止PW喷油泵双头螺柱断裂     

80kA双端进电预焙电解槽技术应用初探

山铝将80kA侧插自焙阳极电解槽改造为80kA中间下料预焙阳极电解槽，通过调整系列电流强度、降低平均电压、控制分子比和电解质成分、应用氧化铝浓度自适应控制技术、钢爪炭素保护环技术、先进的内衬材料、内衬结构技术及干法净化等技术，使80kA预焙槽的电流效率达到91．66％，吨铝直流电耗降为13696kW．h，集气效率达到98％。     

钢桥面-薄层CRRPC组合结构栓钉连接件抗剪疲劳性能研究

采用推出试验和弯曲疲劳试验,研究钢桥面板与薄层CRRPC铺装层间栓钉连接件抗剪疲劳性能。基于Von Mises材料破坏准则和双线性本构关系,对 推出试验模型进行有限元分析、静力试验和疲劳试验,得到不同加载比和界面联接方式下的滑移-加载循环次数曲线,以及栓钉连接件抗剪承载力;开展足 尺组合梁弯曲疲劳试验,考察组合桥面系统中栓钉整体抗剪疲劳性能。研究结果表明：加载比是影响栓钉抗剪疲劳寿命关键因素之一,对于推出疲劳试验, 加载比建议取0.4;钢板与CRRPC间的黏结效应是影响疲劳寿命另一重要因素,对于存在黏结效应的推出试件,在0.5的加载比下等效疲劳寿命可以达到92.2 万次,但无黏结时,疲劳寿命仅为16.9万次;控制栓钉间距是提高组合桥面抗剪疲劳性能的有效方式,在等效实桥应力幅下,即使钢板-CRRPC间不存在黏结 效应,栓钉布距为125mm×125mm,经过8888.9万次疲劳加载,组合梁界面仍没有发生疲劳破坏。     

防屈曲钢板剪力墙弹性性能及混凝土盖板约束刚度研究

防屈曲钢板剪力墙由内嵌钢板与其两侧的预制混凝土盖板通过螺栓连接而成。预制混凝土盖板与周边框架梁柱之间预留一定间隙,同时在大震下允许混凝土盖板与钢板之间产生相对滑移,以确保两侧混凝土盖板不发生严重破坏,从而保护内嵌钢板获得很好的承载性能和耗能能力。采用数值方法对防屈曲钢板剪力墙在水平荷载作用下的弹性屈曲性能、混凝土盖板的最小约束刚度(厚度)以及连接螺栓的最大间距进行研究,给出了防屈曲钢板墙的结构设计中混凝土盖板约束厚度及连接螺栓最大间距的参考公式。     

高强冷弯型钢骨架墙体立柱轴压性能试验研究及有限元分析

对12根550 MPa高强冷弯型钢骨架墙体立柱进行了足尺轴压试验研究,其中包括6根单面带肋钢板墙体立柱和6根双面板(带肋钢板+石膏板)墙体立柱,在试验研究的基础上建立了墙体立柱有限元分析模型。在有限元分析模型充分得到试验验证的情况下,对影响墙体立柱轴压承载力的钢墙面板、墙体柔性拉条、连接螺钉间距等因素进行参数分析,分析结果可供设计参考。分析结果表明:相同用钢量的平钢板代替带肋钢板对单面钢板墙体立柱轴压承载力有较大的降低作用,但对双面板墙体立柱轴压承载力影响甚微;设置柔性拉条可以提高单面带肋钢板墙体立柱轴压承载力,但对双面板墙体立柱轴压承载力没有影响;连接立柱与墙板的螺钉间距不大于300 mm时,减小螺钉间距并不能提高墙体立柱轴压承载力;墙体周边螺钉间距小于150 mm时,减小墙体周边螺钉间距对墙体立柱轴压承载力提高幅度不大。