Blast response of clay brick masonry unit walls unreinforced and reinforced with polyurea elastomer

Clay brick masonry unit(CBMU) walls are widely used in building structures,and its damage and protection under explosion loads have been a matter of concern in the field of engineering protection.In this paper,a series of full-scale experiments of the response characteristics of 24 cm CMBU walls unreinforced and reinforced with polyurea elastomer subjected to blast loading were carried out.Through setting 5.0 kg TNT charges at different stand-off distances,the damage characteristics of masonry walls at different scaled distances were obtained.The reinforcement effect of different polyurea coating thicknesses and methods on the blast resistance performance of masonry walls under single and repeated loads were also explored.Five failure grades were summarized according to the dynamic response features of masonry walls.Based on the stress wave propagation pattern in multi-media composite structures,the internal stress distribution of masonry walls were analyzed,and the division basis of the masonry walls’ failure grades was then quantified.Combined with Scanning Electron Microscope(SEM)images,the deformation characteristics of soft and hard segments of polyurea and effects of detonation products on microstructures were revealed respectively,which provides an important reference for the design and application of polyurea in the blast resistance of clay brick masonry walls.

Experimental studies on behavior of fully grouted reinforced-concrete masonry shear walls

An experimental study is conducted on fully grouted reinforced masonry shear walls (RMSWs) made from concrete blocks with a new configuration. Ten RMSWs are tested under reversed cyclic lateral load to investigate the influence of different reinforcements and applied axial stress values on their seismic behavior. The results show that flexural strength increases with the applied axial stress, and shear strength dominated by diagonal cracking increases with both the amount of horizontal reinforcement and applied axial stress. Yield displacement, ductility, and energy dissipation capability can be improved substantially by increasing the amount of horizontal reinforcement. The critical parameters for the walls are derived from the experiment: displacement ductility values corresponding to 15% strength degradation of the walls reach up to 2.6 and 4.5 in the shear and flexure failure modes, respectively; stiffness values of flexure- and shear-dominated walls rapidly degrade to 17%–19% and 48%–57% of initial stiffness at 0.50 Dmax (displacement at peak load). The experiment suggests that RMSWs could be assigned a higher damping ratio (～14%) for collapse prevention design and a lower damping value (～7%) for a fully operational limit state or serviceability limit state.

Flexural Behavior of Cross-Connected Brick Masonry Infill Wall Panels Supported on Reinforced Concrete Beam Grids

This paper presents an experimental investigation on the flexural behavior of cross-connected brick masonry infill wall panels supported on reinforced concrete beam grids above and below the walls.The experimental program was comprised of six wall systems.The effect of change in lower beam stiffness relative to the wall and the geometry of the main walls were investigated.From the results of the experimental tests,the increase in the depth of the lower beam grid reduces the deflection,resulting in an increase in the load carrying capacity of the wall.Further,the stiffness of the main walls affects the deflection and the failure load of the cross walls.

Analytical study of performance evaluation for seismic retrofitting of reinforced concrete building using 3D dynamic nonlinear finite element analysis

This paper presents three-dimensional finite element （FE） analyses of an all-frame model of a three-story reinforced concrete （RC） building damaged in the 1999 Taiwan Chi-Chi Earthquake. Non-structural brick walls of the building acted as a seismic resistant element although their contributions were neglected in the design. Hence, the entire structure of a typical frame was modeled and static and dynamic nonlinear analyses were conducted to evaluate the contributions of the brick walls. However, the results of the analyses were considerably overestimated due to coarse mesh discretizations, which were unavoidable due to limited computer resources. This study corrects the overestimations by modifying （1） the tensile strengths and （2） shear stiffness reduction factors of concrete and brick. The results indicate that brick walls improve frame strength although shear failures are caused in columns shortened by spandrel walls. Then, the effectiveness of three types of seismic retrofits is evaluated. The maximum drift of the first floor is reduced by 89.3%, 94.8%, and 27.5% by Steel-confined, FuI1-RC, and Full-brick models, respectively. Finally, feasibility analyses of models with soils were conducted. The analyses indicated that the soils elongate the natural period of building models although no significant differences were observed.

不同填充墙构造方法对RC框架抗震性能影响研究

为定量评估不同填充墙构造方法对钢筋混凝土(reinforced concrete,RC)框架抗震性能的影响,搜集整理国内外砌体填充墙RC框架拟静力试验数据,筛选出19篇文献中共68个数据较为详尽的试件作为样本,分析对比柔性连接填充墙、增强填充墙整体性及设置阻尼耗能装置三类构造方法对试件的峰值点承载力、初始刚度、位移延性系数和等效黏滞阻尼系数4个参数的影响程度。结果表明:相较于传统构造方法,柔性连接填充墙框架的承载力和刚度均有所下降,变形能力提升;增强整体性的方法可提升试件承载力、刚度和变形能力,可作为一种较好的既有框架结构的加固方法;设置阻尼耗能装置虽然结构的承载力和刚度有所降低,但提升了结构的变形能力和耗能能力,在建造成本可接受的情况下可作为新建建筑的韧性提升方案。

木丝水泥填充墙-RC框架抗震性能试验研究

为研究木丝水泥填充墙-钢筋混凝土(RC)框架的抗震性能和破坏机理,共制作五个试件进行低周反复试验,其中一个试件为普通砖填充墙-RC框架对比试件,两个试件为开窗洞的木丝水泥填充墙-RC框架,另外两个试件为添加玻璃纤维网格布的木丝水泥填充墙-RC框架,并分析试件的滞回曲线、骨架曲线、延性系数、耗能情况与刚度退化等指标。试验结果表明,木丝水泥填充墙-RC框架的抗震性能良好,刚度退化速度远小于普通砖填充墙-RC框架,耗能能力在试件开裂后超过普通砖填充墙-RC框架;在木丝水泥填充墙-RC框架上开窗洞后会削弱其承载力,但破坏时裂缝只是沿四个窗角分别向四个填充墙角扩展,最终形成“X”形裂缝,而木丝水泥填充墙-RC框架与混凝土之间的粘结面未被破坏,在木丝水泥填充墙-RC框架表面加入玻璃纤维网格布后可以减少墙面裂纹的产生,且提高了极限承载力和延性系数,并抑制了刚度的快速下降。

Experimental investigation of engineered geopolymer composite for structural strengthening against blast loads

The recent increase in blast/bombing incidents all over the world has pushed the development of effective strengthening approaches to enhance the blast resistance of existing civil infrastructures.Engineered geopolymer composite(EGC)is a promising material featured by eco-friendly,fast-setting and strain-hardening characteristics for emergent strengthening and construction.However,the fiber optimization for preparing EGC and its protective effect on structural elements under blast scenarios are uncertain.In this study,laboratory tests were firstly conducted to evaluate the effects of fiber types on the properties of EGC in terms of workability,dry shrinkage,and mechanical properties in compression,tension and flexure.The experimental results showed that EGC containing PE fiber exhibited suitable workability,acceptable dry shrinkage and superior mechanical properties compared with other types of fibers.After that,a series of field tests were carried out to evaluate the effectiveness of EGC retrofitting layer on the enhancement of blast performance of typical elements.The tests include autoclaved aerated concrete(AAC)masonry walls subjected to vented gas explosion,reinforced AAC panels subjected to TNT explosion and plain concrete slabs subjected to contact explosion.It was found that EGC could effectively enhance the blast resistance of structural elements in different scenarios.For AAC masonry walls and panels,with the existence of EGC,the integrity of specimens could be maintained,and their deflections and damage were significantly reduced.For plain concrete slabs,the EGC overlay could reduce the diameter and depth of the crater and spallation of specimens.

混凝土模卡砖预制墙与人工砌筑墙施工运用比较

结合工程实际,对预制墙板的新老工艺:混凝土模卡砖预制墙与人工砌筑墙进行了施工运用比较。从施工情况、经济指标、工期进度等方面进行了优劣分析,总结出一套相对完整的新老工艺适用条件及选择建议,以供后续预制混凝土构件工程施工参考。

房建工程中墙体砌筑施工与加固工程研究

针对现阶段房建工程中墙体砌筑施工与加固工程的相关问题,分析了墙体砌筑施工的基本步骤和技术要点,提出了嵌入钢筋加固墙体的方法和要点。以某希望小学工程为对象,对墙体的砌筑施工和加固工程进行质量检测控制。结果显示,墙体的物理特性均符合建筑要求,墙体温度均衡,约为16~24℃,相对湿度为4%~13%,全部合格。加固后的墙体相比于未加固墙体刚性程度极大提高,累计耗能提高约2倍。

高延性混凝土加固砌体墙方法研究

总结了采用高延性混凝土面层和条带加固砌体墙,以提高砌体房屋抗震性能的两种方法,并分析它们各自的加固要求和抗剪承载力计算公式,比较加固前后砌体墙抗剪承载力的变化。结果发现:高延性混凝土能大幅提高砌体墙的抗剪承载力,且计算公式反映的加固后墙体的承载力较试验值更偏于安全。

某砖砌体结构UHP-ECC面层加固设计和施工分析

某既有砖砌体结构宿舍楼经结构安全性鉴定,墙体普遍受压承载力和抗震承载力不满足规范要求,必须对其进行抗震加固才能继续使用。提出超高性能工程用水泥基复合材料(UHP-ECC)面层加固法,介绍了UHP-ECC制备方法及对材料性能进行测试,结合工程进行了墙体面层加固设计,确定采用人工抹压10~15mm厚度的面层;详细阐述了UHP-ECC面层加固法各阶段加固施工工艺流程和施工要点。结果表明,制备的UHP-ECC具有良好的和易性,适用于人工抹压面层施工;加固后墙体竖向承载力及抗震承载力显著提高;按照施工工艺要求进行施工,施工便捷,对原建筑使用功能影响较小。

某石砌体住宅楼UHPC抗震加固设计与分析

福建省某石结构体系经过鉴定,墙体承载力及抗震构造措施不满足鉴定标准要求,必须对墙体进行加固以消除安全隐患。依据抗震鉴定报告和现行规范标准要求,对比分析石砌体墙抗震加固方法的适用性,选择采用UHPC嵌缝加固法对石砌体墙进行抗震加固。通过墙体嵌缝加固设计,提出了具有嵌缝工作性的UHPC配合比,对加固前后石砌体墙的抗剪承载力进行验算分析。结果表明:UHPC嵌缝加固法可以明显提高石砌体墙的抗震性能,具有良好的推广和应用前景。

BTRC加固砖墙平面内抗剪力学性能及其增强机理研究

为研究玄武岩纤维编织网增强混凝土(BTRC,basalt textile reinforced concrete)加固砖墙的抗剪性能及其增强机理,对BTRC加固砖墙进行了对角剪切试验研究,考察了单双侧加固、纤维编织网层数以及砌筑砂浆强度对抗剪性能提升效果的影响。试验结果表明:BTRC与砖墙协同工作良好,墙体的抗剪强度、刚度及变形能力显著提高;相同纤维编织网层数下,双侧加固优于单侧;随着纤维编织网层数的增加,双侧加固效果逐渐提升,而单侧加固效果无明显变化;对于低强度砂浆砌筑的墙体,BTRC亦可将墙体的灰缝滑移破坏模式转变为具有多缝开裂特征的对角拉伸破坏,加固效果显著。结合试验结果分析了BTRC加固砖墙受剪破坏过程的受力特征,提出了约束增强机理。基于试验结果和增强机理对BTRC加固砖墙的抗剪承载力计算方法进行了研究。

深圳市某超高层宿舍楼装配式设计技术要点

选取深圳市某超高层员工宿舍楼作为研究对象,详细介绍了装配式设计的总体思路。为满足深圳市装配式建筑专家技术评审要求,本项目采用了户型标准化、构件标准化、全混凝土外墙及铝模施工工艺相结合等策略。首先,通过标准化和模数化方法进行户型设计,并调整平面布局以保证户型尺寸协调一致,减少户型种类。其次,通过整体浇筑外墙并配合铝模施工,避免了传统砌体墙面临的质量缺陷问题,例如开裂、空鼓和渗漏,并提高了施工效率和质量。最后,通过合理设计预制构件连接节点和采取有效构造措施,减少对主体结构的影响。经实践验证,本项目的装配式设计通过了深圳市装配式建筑专家技术评审,并取得了良好效果。本项目的设计经验可为类似项目的设计提供借鉴,并鼓励进一步探索装配式建筑在其他建筑类型中的应用,推动装配式建筑的可持续发展。

某办公大楼砖砌体承重结构UHPC加固设计与施工分析

某砖砌体结构办公大楼经过检测鉴定,墙体受压承载力及抗震性能普遍不满足规范要求,必须对墙体进行加固,才能继续使用。依据抗震鉴定报告和现行规范标准要求,对比分析砖砌体墙体加固方法的优劣,选择UHPC面层加固法,并进行砖砌体墙体20 mm厚UHPC双面加固设计。设计结果表明,加固后的墙体受压承载能力及抗震性能显著增加,且达到安全、经济的效果。为此,梳理UHPC面层加固法加固既有砖砌体墙体的施工步骤,并进行施工分析,包括清洁墙面、清理工作面、填补孔洞并涂刷界面剂、嵌入栓钉并用钢丝连接、进行UHPC抹面和养护等,加固设计与施工分析过程,可供类似工程参考。

FRP加固砖砌体墙抗震性能数值模拟分析

为研究FRP(纤维增强复合材料)加固对砖砌体墙抗震性能的影响,基于ABAQUS有限元分析软件建立了FRP加固砖墙的数值模型,分析了FRP宽度、竖向压应力和砂浆强度等级对砌体墙抗震性能指标的影响规律。结果表明,有限元模型能有效模拟未加固砖砌体墙与FRP加固砖砌体墙的抗震性能。随着FRP宽度的增加,加固砌体墙的极限荷载先增加而后趋于稳定,极限位移逐步增加。随着墙体竖向压应力的增加,砌体墙的极限荷载先增加而后稳定,极限位移逐步降低;随着砂浆强度的增加,FRP加固砌体墙的极限荷载提高较为明显。

碳纤维布用于砖砌体抗震加固的试验研究

通过４片碳纤维布加固砖砌体在周期反复荷载作用下受力性能的试验，研究了粘贴碳纤维布来增强砖砌体抗震能力这种加固方法的有效性。本文研究了碳纤维布加固砖砌体的受力特性，分析了碳纤维布的用量以及贴布方式等因素对砖砌体抗震加固效果的影响。在此基础上，本文提出了碳纤维布加固砖砌体抗剪承载力的简化计算方法，可以满足实际工程设计的要求。

GFRP复合材料加固带壁柱砖墙抗震性能试验研究

对玻璃纤维复合材料(Glass Fiber Reinforced Polymer,GFRP)加固带壁柱砖墙抗震性能进行试验研究。通过1片未加固带壁柱砖墙和8片GFRP加固带壁柱砖墙在低周往复荷载作用下的抗震性能试验,阐述了各试件的破坏特征;研究GFRP加固前后墙体的滞回特性、刚度及退化特性、变形性能、耗能性能等变化规律,以及加固方式、加固量和“对拉”锚固措施对加固效果的影响。研究结果表明:加固方式对墙体的刚度退化性能和变形性能影响不大,但对墙体的耗能性能影响较明显;按照本文提出的加固方式粘贴GFRP能够有效地提高墙体的极限荷载、减缓墙体的刚度退化、增强其变形能力和耗能能力;同时考虑采用混合加固方式、增大加固量、采用锚固措施三因素时,墙体的抗震性能较好。

某住宅楼墙体裂缝事故的分析与处理

介绍某砖混房屋墙体裂缝的分析过程和处理方案,墙体加固采用了砖砌体粘钢筋加固法,处理效果良好。

带竖向构造钢筋再生混凝土砖结构振动台试验研究

提出了带竖向构造钢筋再生混凝土砖砌体结构,进行了2个两层再生混凝土砖砌体房屋结构1/2缩尺模型的模拟地震振动台试验研究,2个结构模型的墙体厚度均为120 mm,一层设有门洞和窗洞,二层设有窗洞。2个模型中,1个为带竖向构造钢筋再生混凝土砖砌体房屋,1个为普通无竖向构造钢筋再生混凝土砖砌体房屋。试验中输入El Centro地震动,测试分析了台面加速度反应、一层和二层顶板加速度反应、结构层间位移反应以及各阶段结构损伤与破坏特征等。研究表明:带竖向构造钢筋再生混凝土砖砌体房屋比普通再生混凝土砖砌体房屋的破坏程度轻,墙体裂缝位置相对错动小,抗震性能显著提高;带竖向构造钢筋再生混凝土砖砌体房屋可用于地震区村镇建筑。