大飞机撞击钢筋混凝土核安全壳模型试验研究增强出版（附加材料可在文章详情页“评审附件”下载）

美国9·11恐怖袭击事件后,核电厂房抵御大型商用飞机恶意撞击成为核安全领域备受关注的热点问题。为真实准确地研究大飞机撞击下核电厂房结构的损伤破坏及振动特性,基于某新型反应堆核电厂房结构,设计了大飞机撞击钢筋混凝土核安全壳模型试验,获得了核安全壳结构遭受大飞机撞击时相对完整的试验数据及物理参数。试验结果表明：当大飞机模型以我国核电厂厂址选择安全导则中建议的基准速度100 m/s撞击时,安全壳模型发生局部碎甲破坏,但壳体的主筋整体性能完好,钢筋网有效阻止了大飞机模型的侵入破坏。依据试验结果研究了钢筋混凝土安全壳结构在大飞机撞击作用下的损伤破坏规律和特点,分析了结构的撞击振动反应特性。根据试验结果反演至原型结构,安全壳结构的环梁牛腿处和筒体与穹顶连接处峰值加速度较大,分别为39.5g和47.2g,底板处水平和竖向峰值加速度相对较小,但仍达到3.45g和4.37g。壳体直接撞击区钢筋发生屈服,而在壳体碎甲区之外,各测点的钢筋应变均小于屈服应变,钢筋未发生屈服,钢筋混凝土壳体未发生由振动导致的破坏。     

核电站在大型商用客机撞击下损伤破坏研究进展

2001年9·11事件后,美国核能管理委员会、核能研究院和能源部以及我国核安全局相继出台相关规范,明确规定核电站设计必须考虑大型商用客机的意外和恐怖性撞击作用。从飞机机身的整体撞击效应、引擎局部撞击效应以及核岛厂房结构振动3方面,回顾了核电站重要基础设施在飞机撞击下损伤破坏的理论模型、原型和缩尺试验以及数值仿真研究等的工作进展,对课题组近年来在该领域的研究工作进行了简要介绍,包括4种典型飞机（F4战斗机、空客A320、A380和新舟MA600）和4类核岛设施（预应力钢筋混凝土屏蔽厂房、普通钢筋混凝土屏蔽与附属厂房、钢板混凝土屏蔽与附属厂房,普通钢筋混凝土大型冷却塔）的精细化有限元模型及其撞击全过程的数值仿真分析。此外,介绍了引擎撞击普通钢筋混凝土和超高性能混凝土靶板的缩尺试验和数值模拟分析工作,以及引擎撞击局部效应的计算方法。最后,指出了该领域已有研究在撞击力计算、整体响应、局部破坏、振动效应和多灾害作用方面的不足和进一步研究方向的建议。     

A cross‐scale refined damage evolution analysis of large commercial aircraft crashing into a nuclear power plant

Since the 9/11 attacks, whether nuclear power plants (NPPs) can withstand the malicious impact of large commercial aircraft has become a question that must be considered in the design phase. Refined model and fine‐scale element reflect more accurately the failure procedure and behaviour. However, due to the exceedingly complex structure of NPP, the traditional meshing method requires a substantial number of geometric operations involving point, line, area, and volume, leading to a tedious modelling process and very high computational costs, as well as making it difficult to modify and optimize the model. This paper combines the scaled boundary finite element method with the octree technique to refine nuclear engineering damage evolution analysis and establish a refined numerical model of the Generation III⁺ NPP, considering the detailed equipment hatch, air intake, and internal steel containment vessel structures. Subsequently, the refined damage evolution analysis of a large commercial aircraft crashing into an NPP was developed. The mesh size sensitivity, impact region shape comparison, and the influence of different impact heights were discussed. The results indicate that the cross‐scale refined meshing and analysis method provides a high‐quality discrete grid with fewer elements. Furthermore, this method is highly flexible, more accurately simulating the damage evolution and gradual destruction process. We recommend future structural optimization for the air intake and conducting detailed analyses at this location. The cross‐scale analysis method presented in this paper enables a rapid, refined simulation of a malicious impact by a large commercial aircraft. Additionally, it provides technical support for future studies of the responses of NPPs' internal structures, systems, and equipment under extreme earthquake and other disaster conditions.     

冲击荷载作用下钢筋混凝土梁力学特性数值研究

为研究RC梁在冲击荷载作用下的力学特性,以混凝土强度、纵筋与箍筋配筋率、冲击体的冲击速度以及RC梁的跨度为主要参数对RC梁在冲击作用下的力学性能进行了数值分析,通过与已有试验结果对数值模型进行标定,获取了冲击力时程曲线、位移时程曲线以及破坏形态,验证了数值结果的正确性。分析结果表明,混凝土强度主要影响RC梁的破坏形态;纵筋配筋率对RC梁跨中位移影响较大;冲击体速度会同时对RC梁的破坏区域和跨中位移产生影响;RC梁跨度不仅会改变梁跨中位移也会改变梁的振动频率与反弹速度。     

锈蚀钢筋混凝土梁抗弯承载力计算方法

目前对锈蚀钢筋混凝土梁抗弯承载力的研究主要考虑锈蚀程度的影响,忽视了构件本身参数不同对承载力退化的影响,导致不同学者提出的锈蚀钢筋与混凝土的协同工作系数差异较大。为合理评估既有锈蚀钢筋混凝土梁的剩余承载力,首先对锈后无黏结钢筋混凝土受弯构件进行模拟试验与有限元分析,系统分析严重锈蚀混凝土构件钢筋应力水平的主要影响因素,发现截面配筋指标可综合反映混凝土强度和截面配筋率对受拉钢筋应力水平的影响,并确定基于截面配筋指标的锈后无黏结混凝土梁受拉钢筋强度利用系数;对一般锈蚀钢筋混凝土梁抗弯承载力的退化机理进行深入分析,综合考虑钢筋锈蚀程度和截面配筋指标的影响,建立一般锈蚀混凝土梁钢筋强度利用系数计算公式;提出概念明确、通用性强的锈蚀钢筋混凝土梁抗弯承载力计算方法;与大量的试验结果进行对比验证,计算方法的吻合性较好。     

Influence of chloride corrosion on the effective mechanical properties of steel reinforcement

This paper presents a methodology to develop advanced reduction factors for the effective mechanical properties of corroded steel reinforcement of reinforced concrete (RC) members. The reduction factors (mainly developed for bare steel reinforcement) reported in the literature scatter over a large range. In this regard, critical questions arise, such as the reliability and accuracy of the reduction factors of bare steel bars to evaluate residual capacity of corroded RC structure. This paper will provide answers to these questions based on reviewing past studies and the results observed from experimental inspection of corroded steel reinforcement carried out in this research. The results show using the reduction factors of bare steel bars to estimate residual capacity of corroded RC structures is not safe because they are significantly lower than the reduction that happens in real corroded RC columns.     

悬链线效应下钢筋与混凝土黏结锚固性能试验研究

为研究悬链线效应下锚固钢筋与混凝土之间的黏结破坏,以及在RC框架结构连续性倒塌过程中钢筋拉断和黏结失效的先后顺序,分析锚固长度、钢筋布置方式对黏结锚固性能的影响。将钢筋锚固于钢筋混凝土柱中,通过自制的自平衡加载装置,实现对框架结构梁端破坏而钢筋未拉断时形成悬链线受力机制的钢筋进行加载。试验结果表明：锚固钢筋与混凝土之间发生劈裂破坏,而锚固钢筋并没有被拉断,所以在RC框架结构抗倒塌设计中不宜采用直锚的锚固形式,而应该采用其他有效的锚固形式。此外,单排钢筋布置有利于提高锚固钢筋与混凝土之间的平均黏结应力,较双排钢筋布置下的约提高15%。     

An investigation of ballistic response of reinforced and sandwich concrete panels using computational techniques

Structural performance of nuclear containment structures and power plant facilities is of critical importance for public safety. The performance of concrete in a high-speed hard projectile impact is a complex problem due to a combination of multiple failure modes including brittle tensile fracture, crushing, and spalling. In this study, reinforced concrete (RC) and steel-concrete-steel sandwich (SCSS) panels are investigated under high-speed hard projectile impact. Two modeling techniques, smoothed particle hydrodynamics (SPH) and conventional finite element (FE) analysis with element erosion are used. Penetration depth and global deformation are compared between doubly RC and SCSS panels in order to identify the advantages of the presence of steel plates over the reinforcement layers. A parametric analysis of the front and rear plate thicknesses of the SCSS configuration showed that the SCSS panel with a thick front plate has the best performance in controlling the hard projectile. While a thick rear plate is effective in the case of a large and soft projectile as the plate reduces the rear deformation. The effects of the impact angle and impact velocity are also considered. It was observed that the impact angle for the flat nose missile is critical and the front steel plate is effective in minimizing penetration depth.     

Life-cycle cost analysis of reinforced concrete structures in marine environments

Chloride-induced corrosion of carbon steel reinforcement is the main cause of deterioration of reinforced concrete (RC) structures in marine environments. One of the ways to protect RC structures from corrosion is to use corrosion-resistant stainless steel reinforcing bars. However, stainless steel is between six and nine times more expensive than carbon steel. Thus, its use can only be justified on a life-cycle cost basis. In the paper a time-variant probabilistic model was presented to predict expected costs of repair and replacement which was then used to calculate life-cycle costs for RC structures in marine environments under different exposure conditions. Results of the life-cycle cost analysis can be applied to select optimal strategies improving durability of RC structures in marine environments, including the use of stainless steel reinforcement.     

配置斜筋的单排配筋混凝土低矮剪力墙动力性能试验研究

在单排配筋混凝土低矮剪力墙的墙体或底部配置斜筋,可限制墙体斜裂缝开展,提高剪力墙的基底抗剪切滑移能力,改善其抗震性能。为了解不同斜筋布置形式对其动力性能与地震损伤破坏机理的影响,进行了3个不同配筋形式的混凝土低矮剪力墙模型振动台试验,包括1个普通单排配筋混凝土剪力墙,1个墙体内配置45°斜筋的单排配筋混凝土剪力墙,1个墙体底部配置45°斜筋的单排配筋混凝土剪力墙。在试验基础上,分析了3个剪力墙模型在弹性、开裂及弹塑性损伤破坏等不同受力阶段的自振特性与地震反应,比较了其破坏形态和加速度、位移时程反应。研究结果表明,配置斜筋能有效地提高单排配筋混凝土低矮剪力墙的抗震能力。     

核电站安全壳锚固区局部应力研究

针对核电站安全壳大吨位钢索张拉的结构安全性,用三维有限元方法建立考虑锚具、网格钢筋以及孔道影响的精细分析计算模型,研究了锚固区混凝土的主应力分布状况以及传递机理,结合锚固区混凝土局部承压应力分布规律,为优化锚具结构和降低成本提供理论依据。研究结果表明,用网格筋代替螺旋筋可以提高试件开裂承载力并可以有效地控制劈裂裂缝的开展;张拉过程中锚具本身的应力低于材料的屈服应力;锚垫板下侧的拉裂破坏是可能导致核电站安全壳专用锚具在钢索张拉过程中损伤的主要破损类型。     

钢法兰-榫式连接的装配式RC柱抗震性能试验研究

结合干式连接和湿式连接的优点提出了一种用于装配式钢筋混凝土柱(reinforced concrete,RC)的钢法兰-榫式连接,采用试验方法研究了该类连接的装配式RC柱的抗震性能。设计并制作了1个现浇柱试件和3个钢法兰-榫式连接的装配式柱试件,开展了试件的拟静力试验,研究了各试件的破坏过程及破坏形态,分析了钢法兰-榫式连接方式、钢法兰的钢腹板厚度及混凝土榫头箍筋配筋参数对试件破坏模式、滞回耗能性能、变形能力和关键点处应变的影响。试验结果表明,3个装配式试件的延性系数均大于4.0,变形能力和现浇试件相当,等效黏滞阻尼比均在0.2左右,表现出良好的延性及耗能性能;现浇试件XJ-1与装配式试件ZJ-1以柱底压弯破坏为主,装配式试件ZJ-2和ZJ-3分别发生腹板压弯破坏和榫头剪切破坏,试件ZJ-2的耗能能力较弱而试件ZJ-3的延性较差;腹板的厚度减小会降低钢节点的承载能力并导致腹板和上、下端板的应变增大,混凝土榫头箍筋配筋的减少导致榫头纵筋应变显著增加;装配式柱的柱纵筋的应变与现浇柱相当,表明钢节点能够有效传递纵筋应力。试验结果可为此类连接的装配式RC柱的设计提供参考。     

纤维增强混凝土剪力墙抗震性能试验研究与理论分析

为根本改善混凝土基体的脆性,提高混凝土剪力墙的抗震性能和损伤容限,设计制作6个局部纤维增强混凝土（FRC）剪力墙试件,在试件变形关键部位采用FRC替代普通混凝土,并考虑高轴压比下剪力墙受压钢筋屈曲和受拉纵筋应力集中的问题,在塑性铰区纵向钢筋上设置钢套管,以改善受力钢筋的稳定性和变形性能。通过对悬臂剪力墙试件的拟静力试验,研究此类剪力墙的破坏现象、受力机理和滞回特性,探讨轴压比、FRC区高度、纵筋强度和钢套管长度等因素对墙体变形能力及耗能能力的影响。研究表明,与普通混凝土剪力墙试件相比,塑性铰区采用FRC的剪力墙试件具有较高的损伤容限和变形能力;提高钢筋强度和延性以及在纵筋上设置钢套管,对其抗震性能和耗能能力均具有明显的改善作用。     

在用钢筋混凝土简支桥面梁受弯承载力估算

提出了用钢筋作用系数反映粘结破坏对在用钢筋混凝土简支桥面梁受弯承载力的影响以及在用钢筋混凝土简支桥面梁受弯承载力的估算方法。有不同程度耐久性损伤的 3根已经使用 33年的钢筋混凝土桥面板梁的加载破坏试验 ,验证了钢筋作用系数取值和估算方法的合理性 ;有关文献的试验结果也验证了估算方法的可靠性。     

Parametric study of seismic performance of super-elastic shape memory alloy-reinforced bridge piers

One of the important measures of post-earthquake functionality of bridges after a major earthquake is residual displacement. In many recent major earthquakes, large residual displacements resulted in demolition of bridge piers due to the loss of functionality. Replacing the conventional longitudinal steel reinforcement in the plastic hinge regions of bridge piers with super-elastic shape memory alloy (SMA) could significantly reduce residual deformations. In this study, numerical investigations on the performance of SMA-reinforced concrete (RC) bridge bents to monotonic and seismic loadings are presented. Incremental dynamic analyses are conducted to compare the response of SMA RC bents with steel RC bents considering the peak and the residual deformations after seismic events. Numerical study on multiple prototype bridge bents with single and multiple piers reinforced with super-elastic SMA or conventional steel bars in plastic hinge regions is conducted. Effects of replacement of the steel rebar by SMA rebar on the performance of the bridge bents are studied. This paper presents results of the parametrical analyses on the effects of various design and geometric parameters, such as the number and geometry of piers and reinforcement ratio of the RC SMA bridge bents on its performance.     

冷挤压套筒连接RC装配式剪力墙抗震性能试验研究

为解决RC装配式剪力墙钢筋连接施工和质量检验困难的问题,提出了一种采用冷挤压套筒钢筋连接方式的装配式剪力墙构造形式。为探明此连接方式装配式剪力墙的可行性及其抗震性能,完成7个装配式剪力墙试件和2个现浇剪力墙对比试件的拟静力试验。对试件的水平荷载-侧移曲线及其特征点、钢筋应变进行了分析。结果表明：装配式剪力墙试件和现浇剪力墙试件均为压弯破坏。在简化构造的情况下,冷挤压套筒连接能有效传递钢筋拉压力。采用该连接的装配式剪力墙具有良好的抗震性能,耗能能力、延性均与现浇剪力墙试件接近。在轴压比为0.25~0.6范围内,轴压比增大,承载力增大,极限位移角减小;在剪跨比为0.9~1.35范围内,剪跨比增大,承载力减小,极限位移角增大,刚度退化更为平缓。     

Strain monitoring of RC members strengthened with smart NSM FRP bars

Fiber-reinforced polymer (FRP) bars can be used as internal reinforcement for new reinforced concrete (RC) structures and as near-surface mounted (NSM) reinforcement for the strengthening of RC structures. The NSM method is an emerging strengthening technique for RC structures, where FRP bars are embedded into grooves cut in the cover of RC members. In both cases, strain monitoring of the FRP bars is desirable either for the investigation of the structural behavior or for the long-term health monitoring of the structure. This paper presents a study in which fiber-optic sensors were embedded into glass FRP (GFRP) bars to produce smart GFRP bars for NSM applications. The manufacturing process of the smart FRP bars is illustrated and their performance in tensile, bond and beam flexural tests is examined to assess the effectiveness of these smart FRP bars for achieving the dual purpose of structural strengthening and strain monitoring. On the basis of the test results, the advantages and limitations of fiber-optic sensors compared to electrical strain gages in the strain monitoring of NSM FRP bars are discussed. The bond and beam test results also confirm the effectiveness of the NSM method for the strengthening of RC structures.     

节点加强后钢筋混凝土梁柱节点剪切性能的二维有限元分析

本文以研究节点加强后钢筋混凝土(RC)梁柱节点的力学特性为目的,将加强情况、主筋与混凝土的粘结特性、节点的破坏模式以及裂缝模型作为参数,对RC梁柱节点进行二维有限元(2DFEM)分析,分别考察了节点的荷载变形特性、节点变形模式、混凝土的损伤和梁主筋的应变分布。试验和2DFEM分析表明,节点加强后能防止梁主筋的粘结滑移、减少并延缓节点混凝土的损伤,使RC节点由加强前的节点剪切破坏模式转变成梁端的弯曲破坏模式,从而提高RC梁柱节点的抗剪性能和延性。     

Behavior and capacity of RC beams strengthened in shear with NSM FRP reinforcement

A recent and promising method for shear strengthening of reinforced concrete (RC) members is the use of near-surface mounted (NSM) fiber-reinforced polymer (FRP) reinforcement. In the NSM method, the reinforcement is embedded in grooves cut onto the surface of the member to be strengthened and filled with an appropriate binding agent such as epoxy paste or cement grout. Only a few studies have been conducted to date on the use of NSM FRP reinforcement for shear strengthening of RC beams. These studies identified some critical failure modes related to debonding between the NSM reinforcement and the concrete substrate. However, more tests need to be conducted to identify all possible failure modes of strengthened beams. Moreover, virtually no test results are available on the behavior of shear-strengthened beams containing steel shear reinforcement, and on the effect of variables such as the type of epoxy used as groove filler. This paper illustrates a research program on shear strengthening of RC beams with NSM reinforcement, aimed at gaining more test results to fill the gaps in knowledge mentioned above. A number of beams were tested to analyze the influence on the structural behavior and failure mode of selected test parameters, i.e. type of NSM reinforcement (round bars and strips), spacing and inclination of the NSM reinforcement, and mechanical properties of the groove-filling epoxy. One beam strengthened in shear with externally bonded FRP laminates was also tested for comparison purposes. All beams had a limited amount of internal steel shear reinforcement to simulate a real strengthening situation. Test results are presented and discussed in the paper.     

使用年限为50年的下承式混凝土桥梁的非线性有限元分析

将足尺梁(rnskldsvik桥,瑞士)的非线性有限元模型与荷载试验进行分析比较。为确定桥梁的承载力,进行了1次基于欧盟基金项目——"可持续桥梁:评估未来交通需求与延长使用寿命"的倒塌试验,该有限元模型介绍了新型的材料本构关系模型。根据桥梁的特性,对4种材料分别建模:混凝土、钢筋、碳纤维加强筋和钢/混凝土界面。以不可逆热力学理论为基础,构建了混凝土材料的损伤力学模型。这确保与经典力学理论保持一致性。钢筋和碳纤维加强筋采用经典等向硬化弹塑性本构模型。钢/混凝土界面假定会发生锈蚀。数值分析结果与试验结果相吻合。基于该有限元模型,研究均匀腐蚀引起材料的局部退化。引起局部退化的原因有2个:钢筋有效界面的减少和钢/混凝土界面粘结强度退化。尽管缺少桥梁腐蚀方面的文献资料,但是此研究成果仍然有价值,可采用文献中的试验数据对其进一步验证。