Posts tagged ‘Concrete’

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为对比小震情况下混凝土抗拉刚度对结构分析的影响,测试三种本构对结构分析的影响:(1)不考虑受拉本构;(2)真实考虑受拉的影响;(3)受拉本构按弹性考虑。以下测试中,所有模型使用的单元类型均一致,均采用纤维梁柱模型,变化的只是受拉部分的本构。

  • 测试模型一(Example 1

在后处理中查看结构的响应可以发现,所有情况钢筋的应变均不大于钢筋的屈服应变且远小于混凝土的峰值应变,表明结构基本处于弹性。通过三种不同受拉本构的分析模型结果看出,不考虑受拉和真实考虑受拉,分析的顶点位移和基底剪力结果均十分吻合,但这两种分析结果均和受拉本构按弹性考虑时的分析结果相差很大。

  • 测试模型二(Example 2

这个模型的分析结果与第一个一样,在后处理中查看结构的响应可以发现,所有情况钢筋的应变均不大于钢筋的屈服应变且远小于混凝土的峰值应变,表明结构基本处于弹性。通过三种不同受拉本构的分析模型结果看出,不考虑受拉和真实考虑受拉,分析的顶点位移和基底剪力结果均十分吻合,但这两种分析结果均和受拉本构按弹性考虑时的分析结果相差很大。

  • 小结(Conclusion

通过这两个小例子可以定性说明:

(1)一般情况,忽略混凝土的受拉本构,对结构的整体响应分析结果影响不大(虽然这个测试的是小震)。

(2)即便结构基本处于弹性(应变小于钢筋和混凝土的屈曲应变),混凝土的受拉区按弹性考虑时的结构整体响应分析结果可能和真实考虑混凝土受拉时的分析结果相差很大。因此反过来也可以说,平时在一般结构分析软件中,采用弹性单元进行小震动力弹性时程分析获得的结构整体响应可能和真实响应相差很大。


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  • 致谢(Acknowledgements

感谢师弟 杨光吴梓楠 提供的模型。

  • 注释 ( Comments )

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[书]PERFORM-3D原理与实例 – 第3章 – 钢筋与混凝土材料的单轴本构关系

[Book] PERFORM-3D Theory and Tutorials – Chapter 3 – Uniaxial Constitutive Model of Steel and Concrete Material


  • 章节内容简介 [ Chapter Content Abstract ]

材料非线性问题是建筑结构非线性分析中经常涉及到的问题,计算中采用的材料本构模型是否合理,直接影响弹塑性分析结果的精度,进而影响建筑结构的抗震性能评估结果。本章首先对几种典型的钢筋与混凝土材料的单轴本构进行介绍,在此基础上对PERFORM-3D [1,2]中单轴本构的处理进行介绍,并结合PERFORM-3D的规则给出常用钢筋与混凝土材料的单轴本构定义方法。

Material nonlinearity problems are very common in nonlinear structural analysis. Whether the nonlinear material model used in numerical calculation is reasonable directly influence the reliability of elastoplastic analysis results, which will further affect the seismic performance evaluation of structures. In this chapter, several typical uniaxial constitutive models of steel and concrete was first introduced. On this basis, uniaxial steel and concrete constitutive models in PERFORM-3D were explained in detail. The contents cover detailed explanation of the ‘YULRX’ backbone and the Hysteresis loops in PERFORM-3D. After that, uniaxial constitutive model properties for several commonly used steel and concrete materials were defined based on the rules of PERFORM-3D.

  • 示例页面 [ Sample Pages ]


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PS. 如有错误,请批评指正。如果你喜欢,请在上面 点个赞 吧!!详细内容请阅读书本!! :-)  :-)  :-

Please correct me if I’m wrong. If you like this posts, please give me a “thumbs up” rating on the button above! For more information about this Chapter please refer to the book!!  :-)  :-) )

  • 相关链接[ Acknowledgements ]

[01] 书《PERFORM-3D原理与实例》 汇总页面 (PERFORM-3D Theory and Tutorials Book Page )

[02] [Book][PERFORM-3D Theory and Tutorials — Table of Contents] [目录英文版]

[03] [Book][PERFORM-3D Theory and Tutorials – Foreword ] [前言英文版]

[04] [书]PERFORM-3D 原理与实例 – 第 1 章 – PERFORM-3D软件介绍 ( PERFORM-3D Theory and Tutorials – Chapter 1 :  Introduction of PERFORM-3D )

[05] [书]PERFORM-3D 原理与实例 – 第 2 章 – 入门实例:平面钢框架弹性分析 ( PERFORM-3D Theory and Tutorials – Chapter 2 : Quick Start Example : Elastic Analysis of Plane Steel Frame)

[06] [书]PERFORM-3D 原理与实例 – 第 3 章 – 钢筋与混凝土材料的单轴本构关系 ( PERFORM-3D Theory and Tutorials – Chapter 3 : Uniaxial Constitutive Model of Steel and Concrete Material )

[07] [书]PERFORM-3D 原理与实例 – 第 4 章 – 塑性铰模型 ( PERFORM-3D Theory and Tutorials – Chapter 4: Plastic Hinge Model )

[08] [书]PERFORM-3D 原理与实例 – 第 5 章 – 纤维截面模型 ( PERFORM-3D Theory and Tutorials – Chapter 5: Fiber Section Model )

[09] [书]PERFORM-3D 原理与实例 – 第 6 章 – 剪力墙模拟 ( PERFORM-3D Theory and Tutorials – Chapter 6: Shear Wall Simulation )

[10] [书]PERFORM-3D 原理与实例 – 第 7 章 – 填充墙模拟 ( PERFORM-3D Theory and Tutorials – Chapter7: Infilled Wall Simulation )

  • 购书链接 [ Links to Buy the Book ]

[1] 中国建筑出版在线(http://book.cabplink.com)

http://book.cabplink.com/bookdetail.jsp?id=64317&nodeid=1439

[2] 京东(www.jd.com)

https://item.jd.com/12084377.html (自营)

https://item.jd.com/12860783272.html

https://item.jd.com/12860780755.html

[3] 当当网(http://www.dangdang.com/)

http://product.dangdang.com/1260359350.html

[4] 亚马逊 (https://www.amazon.cn/)

coming soon…..

[5] 天猫书城 (https://www.tmall.com/)

Click me(点击跳转)

  • 致谢 [Acknowledgements ]

十分感谢 师弟 符东龙  章节内容简介 进行了英文翻译!! :-)  :-)  :-)  :-) 

Concrete06是基于Thorenfeldt曲线建立的考虑混凝土抗拉强度、非线性受拉硬化及受压性能的单轴本构。

  • 材料参数(Material Parameters

Concrete06C

(Figure from : http://opensees.berkeley.edu/wiki/index.php/File:Concrete06C.png )

fc:混凝土28天抗压强度(concrete compressive strength at 28 days );

e0:混凝土峰值强度对应的应变,即fc对应的应变(concrete strain at maximum strength);

n:受压应力—应变曲线的形状系数(compression shape factor);

k:峰值压应力后的应力—应变曲线的形状系数(post-peak compression shape factor);

alphal:定义受压残余塑性应变的参数(α1 parameter for compression plastic strain definition);

fcr:混凝土抗拉强度(tensile strength);

ecr:抗拉峰值应力对应的应变(tensile strain at peak stress);

b:受拉硬化曲线的指数(exponent of the tension stiffening curve);

alpha2:定义受拉残余塑性应变的参数(α2 parameter for tensile plastic strain definition)。

  • 测试(Test

con06-material

con06-comp

con06-tensile

con06-comp-ten

  • 参考(References

[1] Concrete06 Material

  • 备注(Comments

感谢 林乐斌 师弟 帮忙整理文档。

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ConcreteD是同济大学李杰老师团队根据中国规范编制的混凝土单轴损伤本构。(ConcreteD is a concrete material based on the Chinese design code.

以下测试一下材料的滞回性能。

  • 材料参数(Material Parameters

fc:混凝土抗压强度(concrete compression strength);

epsc:与混凝土抗压强度对应的应变(concrete strain at corresponding to compressive strength);

ft:混凝土抗拉强度(concrete tensile strength);

epst:与混凝土抗压强度对应的应变(concrete strain at corresponding to tensile strength);

Ec:混凝土初始弹性模量(concrete initial elastic modulus);

alphac:受压段下降参数(compressive descending parameter);

alphat:受拉段下降参数(tensile descending parameter);

cesp:塑性系数,建议取值0.2~0.3(plastic parameter, recommended values: 0.2~0.3);

etap:塑性系数,建议取值1.0~1.3(plastic parameter, recommended values: 1.0~1.3

  • 测试(Test

conD

conD-comp

conD-ten

conD-comp-ten

  • 参考(References

[1] ConcreteD Material

  • 备注(Comments

感谢 林乐斌 师弟 帮忙整理文档。

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Concrete04受压部分的包络线采用Popovics (1973) 提出的单调荷载下的应力—应变关系,并根据Karsan-Jirsa加卸载准则确定其加卸载刚度(线性);受拉部分的包络线由线性上升段和指数下降段组成,其加卸载与再加载刚度取其与原点的割线刚度。(Concrete is a uniaxial Popovics concrete material object with degraded linear unloading/reloading stiffness according to the work of Karsan-Jirsa and tensile strength with exponential decay.)

  • 材料参数(Material Parameters

fc:混凝土28天抗压强度(concrete compressive strength at 28 days );

ec:混凝土峰值强度对应的应变,即fc对应的应变(concrete strain at maximum strength);

Ec:初始刚度(initial stiffness);

fct:混凝土抗拉强度(concrete tensile strength);

et:混凝土极限拉应变(ultimate tensile strain of concrete);

beta:应变达到etu时拉应力与峰值拉应力的比值(the exponential curve patameter to define the residual stress at etu)。

  • 测试(Test

con04-material

con04-ten

con04-comp

con04-comp-ten

  • 参考(References

[1] Concrete04

  • 备注(Comments

感谢 林乐斌 师弟 帮忙整理文档。

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Concrete01是OpenSees中最简单的单轴混凝土材料,它基于Kent-Scott-Park单轴混凝土本构模型,根据Karsan-Jirsa加卸载准则确定其加卸载刚度(线性),该材料不考虑混凝土受拉强度。(Concrete01 is a uniaxial Kent-Scott-Park concrete material object with degraded linear unloading/reloading stiffness according to the work of Karsan-Jirsa and no tensile strength.

  • 材料参数(Material Parameters

Concrete01

(PS. photo from http://opensees.berkeley.edu/wiki/index.php/File:Concrete01.gif .)

fpc:混凝土28天抗压强度(concrete compressive strength at 28 days );

epsc0:混凝土峰值强度对应的应变,即fpc对应的应变(concrete strain at maximum strength);

fpcu:混凝土残余强度(concrete crushing strength);

epscu:混凝土残余强度对应的应变(concrete strain at crushing strength

  • 测试(Test

con01

con01-2

  • 参考(References

[1] Concrete01

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  • 引言(Introduction):

上一篇博文Mander Confined Concrete Model 资料整理总结了Mander模型参数的计算方法,其中该模型十分关键的一个参数为约束混凝土的峰值强度fcc’。关于fcc’的确定,Mander模型原文(Ref. 1)给出的方法为:首先确定两个方向的约束系数,然后通过查图得到约束强度系数(Confined Strength Ratio),进而得到fcc’(博文Mander Confined Concrete Model – Confined Strength Ratio [Mander混凝土本构约束强化系数]》也提到),不方便使用。

原文给出的约束强度系数(Confined Strength Ratio – fcc’/fco’)图:

Confined Strength Ratio - Mander

为此,编制小程序计算Mander模型的约束强度系数,程序如下图所示。

ManderConfinedStrengthRatioCalculator

  • 程序功能(Program Features

程序通过输入两个方向的有效约束系数,计算Mander混凝土模型的约束强度系数,省去查图的过程,方便平时做数值模拟。

This program is for calculation of the Confined Strength Ratio of Mander Confined Concrete Model proposed by Mander  in 1988. 

  • 实例(Examples):

(1)柱子非约束混凝土强度fco’ = 30Mpa,两个方向的约束应力为flx’ = 2.7Mpafly’ = 5.1Mpa,求约束混凝土的峰值强度fcc’(Consider a column with an unconfined strength of fco’=30Mpa and confinning stresses in two direction are flx’= 2.7Mpa and fly’ = 5.1Mpa respectively,calculate the compressive strength  fcc’ of the confined concrete)

约束系数计算( Confinning stresse ratio ):

 flx’/fco’ = 2.7/30 = 0.09;

 fly’/fco’ = 5.1/30 = 0.17;

软件计算过程(Get Confined Strength Ratio by Software):

输入两个方向的约束应力系数,点击“Calculate”按钮。(Input the confinning stresse ratio in two direction and press the ‘Calculate‘ button.

ManderConfinedStrengthRatioCalculator-Example1

约束混凝土强度系数(Confined Strength Ratio):

 fcc/fco’ = 1.6515760

约束混凝土强度(compressive strength  fcc’ ):

fcc‘ = 1.651576 × 30 = 49.55 Mpa

读图(Get Confined Strength Ratio from Figure):

mander强度提高系数-Example1

(2)柱子非约束混凝土强度fco’ = 30Mpa,两个方向的约束应力为flx‘ = 3.0Mpafly’ = 8.4Mpa,求约束混凝土的峰值强度fcc’(Consider a column with an unconfined strength of fco’=30Mpa and confinning stresses in two direction are flx’= 3.0Mpa and fly’ = 8.4Mpa respectively,calculate the compressive strength  fcc’ of the confined concrete)

约束系数计算( Confinning stresse ratio ):

 flx’/fco’ = 3.0/30 = 0.1;

 fly’/fco’ = 8.4/30 = 0.28;

软件计算过程(Get Confined Strength Ratio by Software):

输入两个方向的约束系数,点击“Calculate”按钮。(Input the confinning stresse ratio in two direction and press the ‘Calculate‘ button.)

ManderConfinedStrengthRatioCalculator-Example2

约束混凝土强度系数(Confined Strength Ratio):

 fcc/fco’ = 1.7971448

约束混凝土强度(compressive strength  fcc’ ):

fcc= 1.7971448 × 30 = 53.91 Mpa

读图(Get Confined Strength Ratio from Figure):

mander强度提高系数-Example2

  • 程序下载(Program Download

Download : Mander Confined Strength Ratio Calculator

如有需要,请在评论处留下您的邮箱!If you need this app, please leave your e-mail address through comments and I will send you the app.

  • 参考文献(Reference

[1]  Mander J B, Priestley M J N, Park R. Theoretical stress-strain model for confined concrete[J]. Journal of Structural Division,ASCE. 1988, 114(8): 1804-1826.

  • 相关博文(Related Posts

[1]  Mander Confined Concrete Model 资料整理

[2]  Mander Confined Concrete Model – Confined Strength Ratio [Mander混凝土本构约束强化系数]


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  • 注释 ( Comments )

  ( 软件是免费的。如果你发现软件有bug或者软件使用有问题,请留言给我,或者通过邮箱联系我。邮箱:jidong_cui@163.com . 如果你喜欢这篇博文,请在上面给我 点个赞 吧! :-)   :-)   :-)

  ( This app is free . If  you have found any bug in the program or have any problem when using the program, please don’t hesitate to contact me directly. Email : jidong_cui@163.com. If you like this posts, please give me a thumbs up rating on the above button! )

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  • Kent & Park和修正Kent & Park 混凝土模型 ( Kent & Park vs Modified Kent & Park Concrete Model )

Kent & Park混凝土应力应变模型由Kent和Park[1]于1971年提出,该模型既可以考虑约束混凝土又可以考虑非约束混凝土。但对于约束混凝土,该模型仅考虑箍筋对混凝土的延性提高作用,并不考虑箍筋对混凝土强度的提高作用。因此,Scott、ParkPriestley[2]于1982发表的文章中又对改模型进行了修正,通过引入强化系数K,同时考虑了箍筋对混凝土的延性和强度的提高作用,这一模型被称为修正的Kent & Park模型。由于Kent & Park类模型的简单而不失精度的特性,使得模型应用十分广泛。OpenSees中的Concrete 01Concrete 02单轴混凝土材料受压部分的骨架曲线就是基于Kent & Park类模型。

  • Kent & Park混凝土模型( Kent & Park Concrete Model)

Kent Park

KentPark-Equation

 

  • 修正Kent & Park混凝土模型( Modified Kent & Park Concrete Model)

Modified Kent Park

Modified-Kent-Park-Equation

 

  • 整理成Excel (Convert to Excel Document)

KentParkExcel

  •  实例 (Example)

KentPark-Example

  • 结果(Results)

KentPark-Results

  • 文档下载(Document Download

Download : Modified Kent & Park Concrete Model 资料整理 (Under Construction)

  • 相关博文(Related Posts

[1]  Mander Confined Concrete Model 资料整理

[2]  Mander Confined Concrete Model – Confined Strength Ratio [Mander混凝土本构约束强化系数]


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  • 注释 ( Comments )

整理了Modified Kent & Park Concrete Model 约束混凝土本构模型的参数计算方法,编制了相应的Excel表格,希望对大家有用。如有错误或遗漏,欢迎大家批评指正。

  ( 邮箱:jidong_cui@163.com . 如果你喜欢这篇博文,请在上面给我 点个赞 吧! :-)   :-)   :-)

  ( Email : jidong_cui@163.com. If you like this posts, please give me a thumbs up rating on the above button! )

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