【作者】 赵俊贤；

【导师】 吴斌；

【作者基本信息】 哈尔滨工业大学 ， 防灾减灾工程及防护工程， 2012， 博士

【摘要】 防屈曲支撑是一种利用钢材宏观上发生轴向拉压塑性变形来消耗地震能量的位移相关型阻尼器，同时也是一种宏观上不会发生屈曲的钢支撑抗侧力构件，其主要由承受轴力的钢支撑内芯以及防止内芯屈曲的外包约束构件两部分组成。由于受到约束构件的外围套箍作用，在中震和大震作用下，钢支撑内芯可以在拉压受力状态下全截面充分屈服耗散地震能量而不会发生大幅值屈曲。这种特殊的受力特性使其可以最大限度地发挥钢材良好的耗能能力，避免主体结构在大震中发生严重损伤，因此开展防屈曲支撑耗能减震技术的研究对于提高建筑结构大震不倒甚至大震可修的能力具有十分重要的现实意义。本文主要研究全钢防屈曲支撑的抗震性能及稳定性设计方法，主要研究内容及结论如下：（1）在第2章中，针对传统焊接十字形内芯防屈曲支撑的缺点，提出一种新型全角钢防屈曲支撑。首先，通过第一批试验研究了其抗震性能，分析表明，新型支撑所采用的内芯无焊接技术方案可以很好地解决传统焊接内芯构造所引起的技术问题和性能问题。最后，分析了试件的破坏模式及支撑端部转角特点，发现了铰接支撑端部的刚体转动特性。试验结果表明，支撑内芯外伸段即使在满足传统构造要求的前提下依然会较早发生屈曲破坏，这种破坏模式与支撑端部的刚体转角有关。（2）在第3章中，针对第一批试验所发现的与防屈曲支撑稳定性有关的新问题，作者开展了第二批试验以深入研究支撑端部转动对内芯外伸段平面内稳定性的影响。首先，分析了试件的滞回性能、破坏模式以及支撑端部转角特性，并发现了三种支撑端部转动模式。然后，揭示了内芯外伸段的屈曲破坏机理，以及支撑端部转角特性与支撑整体弯曲受力特性之间的相关关系，并讨论了支撑端部转动模式的影响因素。最后，分析了支撑端部转角的基本构成，并提出了刚体转角变形的计算方法，为后续相关理论研究奠定基础。（3）在第4章中，针对第一批和第二批试验所发现的新问题以及防屈曲支撑稳定性研究的共性问题，提出了考虑节点转动的铰接防屈曲支撑内芯外伸段平面内稳定设计方法。首先，在整体刚体转动变形的基础上考虑支撑的端部两点接触效应推导出内芯外伸段控制截面的弯矩及支撑端部转角计算公式。然后，利用前两批试验结果对理论分析结果进行验证，分析结果表明，所提出的设计方法可以合理地反映内芯外伸段的压弯复合受力状态。最后，通过理论分析结果对影响内芯外伸段稳定性的因素进行了参数分析，讨论了最优设计参数的取值范围并给出了设计建议，为相关稳定性设计提供参考。（4）在第5章中，作者开展了第三批试验以研究支撑端部转动对整体稳定性的影响。首先分析了试件的滞回性能、支撑端部转角特性以及约束构件的弯曲受力特性，并讨论了支撑端部转角及转动模式对整体稳定性的影响。试验中发现了铰接支撑端部刚体转动后会在约束构件端部引起附加端弯矩这一受弯特性，导致支撑在满足传统设计要求的前提下仍然提前发生整体屈曲破坏，表明传统设计方法是偏于不安全的。然后，揭示了约束构件端部弯矩的产生机理，并提出了端部弯矩的简化预测方法，为后续相关理论研究奠定基础。（5）在第6章中，基于第三批试验所发现的新问题以及传统设计方法存在的关键理论问题，提出了铰接防屈曲支撑平面内整体稳定设计方法。首先，提出了判断端部接触状态的理论与试验判定方法，确定了支撑的理论分析模型，提出了整体稳定设计准则。然后，利用第三批试验结果对理论分析结果进行验证，分析表明，所提出的设计准则可以合理地反映端部两点接触作用、内芯屈曲以及摩擦力的综合影响。最后，基于理论分析结果对影响铰接防屈曲支撑整体稳定性的因素进行了参数分析，总结了最优设计参数的取值范围并提出了设计建议，为相关稳定性设计提供参考。（6）为方便实际应用，作者在第7章中提出了基于弯矩放大系数的稳定性实用设计方法及统一设计方法。首先，提出了弯矩放大系数的概念，通过多元回归方法得到了弯矩放大系数与关键支撑参数之间的相关公式，进一步提出了平面内稳定实用设计公式，并以全角钢防屈曲支撑为例给出了实用设计方法的实现方法。最后，针对实际设计中存在的问题，提出了防屈曲支撑整体稳定统一设计方法，该方法可以把不同连接特性、端部构造以及受力特性的防屈曲支撑的整体稳定设计进行统一，进一步规范和简化了防屈曲阻尼器的设计。更多还原

【Abstract】 Buckling-restrained braces (BRBs) are one type of displacement-dependentenergy dissipation devices that utilize the axial plastic deformation of steel todissipate seismic energy, and they can also be used as bracing members withoutbuckling in the lateral-load-resisting structural systems. BRBs typically consist oftwo main components, i.e., the steel core member which is intended to be used toresist the axial load only, and the buckling-restraining member (casing) which isdesigned to prevent the core member buckling without resisting axial force. Withthe restraining effect of casing, the encased steel core can yield both in tension andcompression to dissipate seismic energy, without significant buckling, undermedium or severe earthquake. Such special mechanical behavior enables the steelcore to fully dissipate the energy through cyclic loading, so that the damage to mainstructures can be significantly reduced. Hence, it is highly meaningful for damagemitigation of main structures under serve earthquake by developing such promisingpassive energy dissipation technology.This study focuses on the seismic behavior and stability design methods of all-steel BRBs, and it contains the following six parts:(1) A novel type of angle steel buckling-restrained brace (ABRB) is proposedin Chapter2based on the technical problems of traditional BRBs with weldingcruciform-shape as the cross-section of steel core. Firstly, the seismic behavior ofthe new ABRB was examined by component tests of the specimens in the firstgroup. Test results show that the technical problems caused by welding could beresolved by the non-welding technique. Finally, the failure modes andcharacteristics of brace end rotational responses are discussed, and it is found thatthe brace ends of specimens with pinned connections were prone to rotate as rigidbodies when braces yielded. The core extension would experience premature in-plane buckling even though its configuration met the commonly used constructionaldetails. It shows that the buckling at core extension was related to the rigid bodyrotation at the brace ends.(2) In Chapter3, the second group testing was conducted to further investigatethe effect of brace end rotation on the in-plane stability of core extension based onthe newly-found issues in the first group testing. Firstly, the cyclic behavior, failure modes, and characteristics of brace end rotation are discussed, and three brace endrotation modes were observed in the testing. The failure mechanism of buckling atcore extension, the correlation between brace end rotational response and flexuralresponse in the casing, and the influential factors on brace end rotation modes arethen investigated. Finally, a simplified method to predict the rigid body rotationaldemands of brace ends is proposed, which lays basis for corresponding theoreticalstudy in subsequent discussion.(3) The in-plane stability design method for core extension considering theeffects of brace end rotation and contact interaction near core ends is proposed inChapter4, based on the newly-found issues in the first and second group testing andthe common problems in stability design of BRBs. Firstly, the rigid-body rotationaldeformation configuration is taken as the initial geometric imperfection, and secondorder analysis is performed on the core extension based on such configurationconsidering the effect of two-point contact at the core ends. The bending momentdemand on the controlled cross-section of core extension and brace end rotationaldemand are then derived. Secondly, the proposed design method is validated by thetest data of the first and second group testing. It shows that the actual compression-flexure behavior of core extension can be properly predicted by the proposed designmethod. Finally, parametric study is conducted to examine the effect of key BRBparameters on the in-plane stability of core extension, and the optimal design valuesfor the parameters and design recommendations are then provided, which can beused as future guideline for stability design of core extension.(4) The third group testing was conducted in Chapter5to examine the effect ofbrace end rotation on global stability. Firstly, the hysteretic response, brace endrotational response and the flexural response in the casing are presented, and theeffects of brace end rotation and rotation modes on global stability are discussed. Itis found that end bending moments would be induced in the casing due to theoccurrence of rigid-body rotation at the brace ends and two-point contact near coreends, which resuled in premature global buckling of the specimens. It indicates thatthe commonly used global stability design criterion is unconservative. Theoccurrence mechanism of end bending moments is then discussed and a simplifiedprocedure to predict the magnitudes of end bending moments is proposed, whichlays basis for corresponding theoretical study in subsequent discussion.(5) In Chapter6, the in-plane global stability design method for pin-connected BRBs with end collars is proposed based on the newly-found issues in the thirdgroup testing and the common problems for traditional design method. Firstly, theexperimental and theoretical procedure to estimate the contact states near core endsare proposed and the theoretical models for BRBs are then determined based on theproposed procedure. The global stability design criterion is then proposed. Secondly,the analytical results and the proposed design criterion are validated based on thetest results of the third group testing. It shows that the combined effect of bendingmoments induced by brace end rotation and core buckling and the frictional forcecan be properly reflected by the proposed design criterion. Finally, parametric studyis conducted to investigate the effect of key BRB parameters on global stabilitybased on the analytical results, and the optimal design values of key parameters anddesign recommendations are then summarized, which can provide future guidelinefor global stability design of BRBs.(6) To facilitate actual design, a simplified in-plane stability design formulabased on the moment amplification factor is proposed in Chapter7. Also proposedis the unified global stability design method. Firstly, the concept of momentamplification factor is proposed and the correlation formulas among momentamplification factor and key BRB parameters are obtained by multiple regression.The simplified in-plane stability design method is then proposed based on thecorrelation formulas with the ABRB as an example. Finally, the unified globalstability design method is proposed based on the shortcomings in stability design ofBRBs. This method can be used to unify global stability design of BRBs withvarious brace end connections, brace end configurations and mechanical behavior,which helps to standardize and simplify BRB design.更多还原