Outline
- Abstract
- Keywords
- Clc Number
- 1 Introduction
- 2 a Modified Frp Confined Concrete Model
- 3 Implementation and Coding in Opensees
- 4 Numerical Implementations
- 4.1 Monotonic Axial Loading Tests
- 4.2 Cyclic Loading Full Strengthening Column Tests
- 4.3 Cyclic Loading Partially Strengthening Tests
- 5 Conclusions
- Acknowledgements
- Appendix A: Head File of Usermat
- Appendix B: Source File of Usermat
- Appendix C: Tcl Command Definition of Usermat
- References
رئوس مطالب
- چکیده
- کلید واژه ها
- 1. مقدمه
- 2. یک مدل اصلاح شده بتن محصورشده با FRP
- 3. اجرا و کدنویسی در OpenSees
- 4. پیاده سازی عددی
- 1.4 آزمایشات بارگذاری محوری یکنواخت
- 2.4 آزمایشات بارگذاری چرخه ای ستونهای کامل تقویت شده
- 3.4 آزمایش های بارگذاری سیکلی نمونه های نیمه تقویت شده
- 5. نتیجه گیری
- پیوست A : فایل های اصلی مصالح کاربر (UserMat)
- پیوست B : فایل های منبع UserMat
- پیوست C : تعریف دستور TCL مربوط به UserMat
Abstract
OpenSees is a well-recognized open source platform with high compatibility, and it has a well-developed fiber element method to cope with nonlinear structural analysis. Fiber reinforced polymer (FRP) confined concrete can effectively improve the seismic performance of concrete structures. However, sophisticated constitutive models for FRP confined concrete are not available in the current version of OpenSees. In this paper, after reviewing several typical FRP confined concrete constitutive models, a modified constitutive model for FRP confined concrete in circular sections was proposed based on Lam and Teng (2003)’s model with four main modifications including the determination of FRP rupture strain, ultimate condition, envelope shape, and hysteretic rules. To embed the proposed constitutive model into OpenSees is a practical solution for engineering simulation. Hence, the secondary development of OpenSees New UserMat was briefly demonstrated and a set of critical steps were depicted in a flow chart. Finally, with the numerical implementations of a series of FRP confined concrete members covering a wide range of load cases, FRP confinement types and geometric properties, the utility and accuracy of the proposed model compared with Lam and Teng (2003)’s model and new material secondary development in OpenSees were well validated.
Keywords: Constitutive model - FRP confined concrete - OpenSees - Secondary development - User materialConclusions
A modified uniaxial constitutive model for FRP confined concrete in circular sections has been proposed and successfully embedded into OpenSees through new material secondary development. With a series of numerical implementations calibrated against test results, the feasibility and accuracy of the proposed modified model were comprehensively verified. Several conclusions can be drawn.
- The modified model has raised four main modifications based on a prevalent model proposed by Lam and Teng (2003; 2009). The modifications emphasized on the FRP rupture strain, ultimate stress and strain, intercept stress and hysteretic rules have been stated in detail, respectively. It is not only practical and so-called design-oriented, but also of better generality considering the concrete strength and FRP confinement types.
- The computational efficiency of the fiber element method provided by OpenSees is conspicuous, and a fairly numerical precision also can be achieved at the same time. The process of a new material secondary development in OpenSees can be generally used for different materials, so that users can expand their material library according to their specific demand.
- With numerical implementations covering a variety of load cases and FRP confinement types for FRP confined members, the utility and accuracy of the proposed model and new material secondary development in OpenSees have been well verified. The modified model performs better than Lam and Teng (2003)’s model in predicting FRP mechanic behavior, especially for high strength FRP confined concrete.