爆炸荷载作用下承重柱的弹性动力响应分析

为了建立爆炸荷载作用下承重柱构件的弹性动力响应分析方法,进一步奠定研究承重柱非线性抗爆响应和破坏形态的理论基础,该文将承重柱简化为承受轴向荷载的约束梁构件,并基于经典Timoshenko梁理论,通过建立等效频率矩阵、等效荷载向量矩阵以及修正的等效质量矩阵,采用变量分离法联立方程求解,推导出承受恒定轴力的Timoshenko梁在任意横向爆炸荷载作用下的弹性动力响应的解析解;并以此弹性解析方法为基础,进一步分析讨论了爆炸荷载作用下,长细比、初始轴向应变、端部约束条件及荷载参数等因素对承重柱弹性动态响应的影响,研究结果对钢柱或钢筋混凝土柱(RC柱)的抗爆分析与设计有参考作用。     

水下和空中爆炸时混凝土重力坝动态响应对比分析

由于水和空气的物理属性差异以及与爆炸产物的界面作用效应不同,使得水下和空中爆炸冲击波传播特性及其荷载作用下的大坝结构动态响应存在较大的差异。通过构建混凝土重力坝水下爆炸和空中爆炸的全耦合数值仿真模型,考虑炸药起爆、冲击波传播、冲击波与结构的相互作用以及结构的动态响应等复杂过程,在对比分析爆炸冲击波在水下和空中传播特性的基础上研究了水下和空中爆炸冲击波对大坝动态响应及损伤程度的影响。研究表明,水下爆炸冲击荷载作用下混凝土重力坝动态响应及损伤程度均较同等炸药量下空中爆炸冲击荷载作用时大;在研究水工大坝抗爆性能时,应重点关注水下爆炸冲击波传播的特性及大坝在水下爆炸荷载作用下的动态响应。     

复式空心钢管混凝土柱抗爆性能及损伤研究

通过爆炸试验,对复式空心钢管混凝土柱抗爆性能及损伤程度进行研究,并结合所得试验数据进行数值模拟,分析并建立柱的损伤评估准则。结果表明:在折合距离为0.14m/kg~(1/3)试验条件的爆炸荷载作用下,复式空心钢管混凝土柱迎爆面柱中发生了明显的塑性弯曲变形;柱迎爆面压力峰值柱中最高、柱底次之、柱顶最小,且爆炸冲击波对迎爆面柱中造成的破坏最为强烈、柱底次之、柱顶最小;柱端部节点强度与构件整体强度协调对提升复式空心钢管混凝土柱的抗爆性能尤为重要。最终建立了基于固端约束下复式空心钢管混凝土柱中挠度的超压-冲量(P-I)损伤准则及判定公式。     

钢筋混凝土隔离墙抗爆性能数值模拟研究

为了研究钢筋混凝土隔离墙在爆炸荷载作用下的动态响应和抗爆性能,采用LS-DYNA有限元软件建立9 m跨度隔离墙结构简化模型,模拟了不同药量和爆炸距离下隔离墙的动态响应。将模拟结果与经验超压公式计算结果和已有试验结果对比,验证了爆炸荷载和材料参数选取的合理性,分析了结构的破坏过程、冲击波作用规律、墙面荷载分布规律和结构变形情况。结果表明:建立的数值模拟可以较好地模拟爆炸冲击波与结构的相互作用;墙面冲击波压力衰减速率与药量和爆炸距离密切相关,墙面压力衰减幅度可达97.8%。在相同药量时,随着爆炸距离增加,墙体底部压力减小,顶部冲量增加;墙体结构由小变形转变为结构整体的较大变形;比例距离小于0.376■时,墙体底部容易发生剪切破坏。模拟结果可以为抗爆隔离墙的设计提供依据。     

钢板-泡沫铝-钢板新型复合结构降低爆炸冲击波性能研究

泡沫铝材料具有减振和吸收冲击能量的特点,但是单一的泡沫铝材料强度较低.为降低爆炸冲击荷载对框架底层柱的破坏,在两层钢板中间添加一层泡沫铝材料以构成多层复合抗爆结构,从而实现防爆和衰减冲击波的功能.当爆炸冲击波作用到复合结构时,泡沫铝产生塑性变形被压实,由于泡沫铝冲击波阻抗比较低,能够大大地削弱应力波的强度.在这个过程中,空气冲击波能量被减小,和单层材料相比,防爆能力得到提高.在研究过程中,主要进行了理论研究和LS-DYNA有限元动力分析,计算结果表明钢板-泡沫铝-钢板复合结构具有较好的吸能减振效果,可以运用到地面军事工程结构防爆设计中去,以提高地面军事建筑的战时生存能力.     

不同连接方式对钢梁钢柱节点抗爆性能的影响

研究爆炸荷载作用下钢梁钢柱节点的动力学性能,对有效预防整体结构的连续性倒塌具有重要意义。先利用有限元分析软件ANASYS/LS-DYNA对爆炸荷载作用下的钢梁进行数值模拟,并与Amr的实验结果进行对比以验证模型和所用材料参数的合理性;然后研究采用不同连接方式(狗骨式连接和端板螺栓式连接)对钢框架梁、柱节点抗爆性能的影响。研究表明:与端板螺栓式连接相比,在相同爆炸荷载作用下,狗骨式连接时节点的最大应力较小,梁跨中节点的最大挠度最大。由于狗骨式连接在梁的上、下翼缘处进行了一定的削弱处理,使得较长的梁段能同时进入塑性阶段,可有效保护节点。在相同爆炸荷载作用下,端板螺栓式连接时,节点的承载能力和抗塑性变形能力要优于狗骨式连接。     

不同连接方式对钢梁钢柱节点抗爆性能的影响

研究爆炸荷载作用下钢梁钢柱节点的动力学性能,对有效预防整体结构的连续性倒塌具有重要意义。先利用有限元分析软件ANASYS/LS-DYNA对爆炸荷载作用下的钢梁进行数值模拟,并与Amr的实验结果进行对比以验证模型和所用材料参数的合理性;然后研究采用不同连接方式(狗骨式连接和端板螺栓式连接)对钢框架梁、柱节点抗爆性能的影响。研究表明:与端板螺栓式连接相比,在相同爆炸荷载作用下,狗骨式连接时节点的最大应力较小,梁跨中节点的最大挠度最大。由于狗骨式连接在梁的上、下翼缘处进行了一定的削弱处理,使得较长的梁段能同时进入塑性阶段,可有效保护节点。在相同爆炸荷载作用下,端板螺栓式连接时,节点的承载能力和抗塑性变形能力要优于狗骨式连接。     

基于LS-DYNA的大空间柱壳结构爆炸波压力场分析

基于ANSYS/LS-DYNA,在验证模型及参数选取正确及可靠的基础上,建立了大空间柱壳结构在爆炸作用下的冲击波压力场计算模型。引入本征正交分解（POD）法,解决了冲击波荷载的时空差异性和结构表面压力场分布问题,大大减少了大空间结构爆炸动力响应分析的计算量。对大空间柱壳结构在爆炸冲击荷载作用下的压力场进行了数值模拟计算与分析,研究了跨度和矢跨比等因素对结构压力场分布的影响。结果表明,计算模型适用于大空间柱壳结构在爆炸作用下的动力响应计算。     

爆炸冲击荷载作用下SRC柱等效单自由度模型

爆炸冲击荷载作用下结构构件的反应分析方法常用的是等效单自由度模型，在现有的有关资料中，等效单自由度模型主要用于钢筋混凝土构件和钢构件。等效单自由度模型的关键是确定等效弹性位移、破坏位移和屈服强度。以通用有限元分析软件LS—DYNA为基础，研究了钢骨混凝土（SRC）柱在爆炸冲击荷载作用下的反应特征，确定出了等效单自由度模型的等效弹性位移和破坏位移；以常规SRC柱设计理论为基础，提出了等效单自由度模型的等效屈服强度计算公式。最后用所建立的等效单自由度模型和LS—DYNA软件分别对8根SRC柱共48种爆炸冲击荷载工况进行对比分析，验证了所提出的等效单自由度模型。     

地表爆炸荷载作用下大型输水箱涵的毁伤评估及防护效应分析

随着我国跨区域调水工程的增多,箱涵结构的抗爆问题越来越受到重视。考虑爆炸荷载作用下混凝土的应变率效应、流体与固体间的耦合以及结构的非线性动态响应等复杂问题,基于Lagrangian-Eulerian耦合方法建了地表爆炸荷载作用下钢筋混凝土输水箱涵的全耦合模型。通过与已有的经验公式和现场爆炸试验进行对比,分别验证了土体地表爆炸模型和爆炸荷载作用下钢筋混凝土模型的可靠性;对比研究了有水和无水两种工况下箱涵的动力响应及毁伤发展过程,并分析了地表爆炸荷载作用下冲击波的传播特性;同时采用聚苯乙烯泡沫作为箱涵的防护材料,探讨了其对钢筋混凝土输水箱涵抗爆性能的影响。结果表明:突发地表爆炸荷载将对输水箱涵结构的安全性构成巨大的威胁;而在箱涵顶部铺设聚苯乙烯泡沫可以有效地提高其抗爆性能。     

压杆应变式压力传感器在爆炸冲击波载荷测试中的应用

在容器内实施化学爆炸时，容器内壁上冲击波载荷的确定是进行爆炸容器结构动力响应分析、安全评估和工程设计的基础。获得比较准确、可靠的爆炸容器内壁上作用载荷的时间历程及分布情况，对研究结构动力响应意义重大。文章采用压杆应变式压力传感器来测量爆炸冲击波载荷，这种传感器解决了普通传感器在高频压力脉冲下频响低且容易损坏等问题。压杆应变式压力传感器为一细长弹性杆，爆炸冲击波作用在杆的一端，在杆中激发一维弹性应力波，通过测量杆上适当位置处的应变，利用一维弹性应力波理论可以计算出作用在杆端的爆炸冲击载荷。文章根据一维弹性波理论，设计了满足所需频响、上升时间、持续作用时间等参数要求的压杆应变式压力传感器，其材料为高强度钢，采用动态应变放大器和数据采集仪组成测量系统。通过实验，获得了比较完整的容器内壁上冲击波载荷曲线，测量结果的重复性和一致性很好。经分析表明，压杆应变式压力传感器能准确地测得容器内壁上冲击波荷载的幅值和比较完整的曲线，对爆炸冲击波载荷测试来说，是一种比较准确可靠的传感器。     

The effects of explosive blast load variability on safety hazard and damage risks for monolithic window glazing

Although the modelling of built infrastructure subject to blast loading has been well developed, considerable uncertainty remains with respect to explosive loading parameters and structural response. This paper focuses on facade glazing – as this poses significant safety hazards when affected by explosive blast loads. A structural reliability analysis is used to calculate probabilities of glazing damage and safety hazards conditional on given threat scenarios. The analysis considers the variability of explosive blast loading; in particular, from variations in explosive weight, explosion effects in terms of pressure, stand-off distance, inherent blast load variability and model error. Uncertainties in structural response (including the variability in glazing stress limits, situational geometry, fragment drag coefficients and modelling error) are then considered in the analysis. This allows the prediction of likelihood and extent of damage and casualties. It was found that damage and safety hazard risks are very sensitive to the accuracy of the blast loading prediction model and the inherent variability of blast loading.     

Geometrically nonlinear composite beam structures: design sensitivity analysis

The purpose of this paper is to develop a finite element model for optimal design of composite laminated thin-walled beam structures, with geometrically nonlinear behavior, including post-critical behavior. A continuation paper will be presented with design optimization applications of this model. The structural deformation is described by an updated Lagrangean formulation. The structural response is determined by a displacement controlled continuation method. A two-node Hermitean beam element is used. The beams are made from an assembly of flat-layered laminated composite panels. Beam cross-section mass and stiffness property matrices are presented.

Design sensitivities are imbedded into the finite element modeling and assembled in order to perform the structural design sensitivity analysis. The adjoint structure method is used. The lamina orientation and the laminate thickness are selected as the design variables. Displacement, failure index, critical load and natural frequency are considered as performance measures. The critical load constraint calculated as the limit point of the nonlinear response is also considered, but a new method is proposed, replacing it by a displacement constraint.     

内爆作用下RC框架结构SAP数值模拟

利用SAP2000软件,在构件拆除法的基础上增加了爆炸冲击荷载对关键失效构件周围其他构件的直接作用,对内爆作用下的RC框架结构进行了动力非线性分析,并将分析结果与仅采用构件拆除法的分析结果进行了对比。通过对比计算结果可以看出,爆炸冲击荷载对失效构件周围其他构件的直接作用会对RC框架结构的损毁程度产生较大影响。与构件拆除法相比,SAP2000分析方法更符合内爆作用下RC框架结构的实际受荷情况。与利用ANSYSLS/DYNA等大型有限元软件进行显示动力分析相比,SAP2000分析方法更易于掌握,节省时间,更便于广大结构设计人员使用。     

内爆作用下RC框架结构SAP数值模拟

利用SAP2000软件,在构件拆除法的基础上增加了爆炸冲击荷载对关键失效构件周围其他构件的直接作用,对内爆作用下的RC框架结构进行了动力非线性分析,并将分析结果与仅采用构件拆除法的分析结果进行了对比。通过对比计算结果可以看出,爆炸冲击荷载对失效构件周围其他构件的直接作用会对RC框架结构的损毁程度产生较大影响。与构件拆除法相比,SAP2000分析方法更符合内爆作用下RC框架结构的实际受荷情况。与利用ANSYS LS/DYNA等大型有限元软件进行显示动力分析相比,SAP2000分析方法更易于掌握,节省时间,更便于广大结构设计人员使用。     

RC beams under blast load: Reliability and sensitivity analysis

The effects of blast loading on structures can be very dangerous: damages and failures are expected with serious threats to structural safety and human life. Materials stresses and strains are often pushed to the limit and the modelling of these phenomena can be very complex. In order to design blast-resistant structures it is very important to determine what are the key parameters of this problem.This paper presents a reliability and parametric analysis of the response of reinforced concrete (RC) beams under blast loads. The main aim is to highlight the key parameters of the problem in order to produce information useful for the design of reliable blast-resistant RC structures.The beam has been idealised as an equivalent SDOF system, in which strain-rate effects are accounted for. This approach is convenient from a computational point of view and it has been validated by a direct comparison with a more sophisticated finite element model and with experimental results found in literature. Then a sensitivity analysis of the parameters involved in beam response under blast load has been developed. Slenderness (which has a direct effect on stiffness) and peak load prove to be the most important parameters, but span length (which has an important influence on the mass) is also a key parameter. Other variables such as concrete strength and reinforcement ratio do not seem to have a strong correlation with the beam response.     

Analysis of foam claddings for blast alleviation

An analytical Load-Cladding-Structure (LCS) model is proposed to investigate the blast alleviation behavior of sacrificial foam claddings. The deformation of the foam subjected to blast loading is derived based on shock wave propagation theory. The coupled global response of the protected main structure is taken into consideration in the study. Two non-dimensional parameters for the foam cladding are introduced. It is seen that the maximum deflection of the protected structure subjected to a certain explosive load varies with the two non-dimensional parameters of the foam cladding. Based on the LCS model, the foam cladding can be appropriately designed to achieve structural retrofit against blast loads. The maximum allowable blast load for the structure with the protection of a particular foam cladding can be predicted. It is concluded that the efficiency of the structural retrofit based on foam materials depends on the properties of the blast load, the foam cladding as well as the protected structure.     

An inverse approach for pressure load identification

An inverse approach for the identification of pressure loading on a structure has been proposed and developed. In this approach, surface measurements of structural response (e.g. strain, displacement and velocity field measurements, such as can be measured with 3D digital image correlation) are utilized as input data and are combined with numerical simulations to identify the pressure load on a structure. The inverse approach has been verified by numerical benchmarks involving pressure identification under quasi-static as well as dynamic impulse loading conditions, and also been validated by an experiment involving a quasi-static pressure load. The results indicate that the proposed inverse method can identify not only the magnitude of the quasi-static pressure but also the impulsive pressure loading history. The developed inverse approach offers an opportunity to apply inverse analysis techniques to identify interactive pressure loads (such as those resulting from a blast wave) on structures in explosive events.     

基于小样本记录的柱面网壳结构地震响应评估

结构的地震反应可以采用时程分析法或反应谱法来估计,在用时程分析法计算结构抗震设计需求时,中国抗震设计规范规定了选择3条或至少7条地震动记录的准则。可以用峰值加速度（PGA）或加速度反应谱（SA）来对地震动记录进行调幅,但用哪一个地震动强度参数来调幅为最佳还是未知的。该文针对柱面网壳的分析结果表明:合适的地震动强度参数取决于所需的结构反应,为降低由地震动记录间差异引起的结构最大杆件内力、支座反力或基底剪力的变异性,采用PGA调幅地震动记录要优于SA,而对于结构的最大位移反应则恰好相反。由于结构频谱十分密集以及受高阶振动模态的影响,采用反应谱法计算结构最大杆件内力或基底剪力是不合适的。同时,该文计算了采用3条和7条地震动记录准则获得的结构最大杆件内力和基底剪力的统计值,以期能为选择合适的地震动强度参数和地震动记录数量提供依据。     

考虑面力效应的HFR-LWC梁抗爆理论模型与试验验证

现有的抗爆设计规范通常将面力效应看作一种潜在的安全系数,而对面力作用在爆炸加载过程中的变化规律及其对结构抗力的贡献不做深入探索.该文对近距离爆炸荷载进行适当简化,并考虑面力效应的影响,建立一种基于等效单自由度(SDOF)法的梁式构件抗近距离爆炸分析模型.专门设计了一套面力加载装置,对8根考虑面力效应的混杂纤维轻骨料混凝...