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International Journal of Civil Engineering

, Volume 17, Issue 3, pp 333–346 | Cite as

Experimental Study on Seismic Performance of Ungrouted Confined Concrete Masonry Walls with Unbonded Tendons

  • Zhanggen GuoEmail author
  • Songlin Zheng
  • Zhenwen Xu
  • Weimin Sun
Research paper
  • 108 Downloads

Abstract

A novel concrete masonry wall for enhancing seismic behavior is adopted and justified in this paper, namely, ungrouted posttensioned confined concrete masonry (PTCCM) wall with unbonded tendons. The wall is posttensioned as well as confined by the ring beam placed on the top and constructional columns placed at the both ends of the wall. To validate the effectiveness of this technique, 14 walls were tested under lateral cyclic loads. The main parameters studied in this research are prestressing level, opening and horizontal reinforced concrete strip as well as axial load. The damage pattern and failure mode, force deformation response, ultimate strength, ductility and damping coefficient of each wall were carefully studied as well as stiffness degradation. The effects of posttensioning, opening and horizontal reinforced concrete strip on the seismic behavior of the PTCCM walls were analyzed in detail. The test results indicate that the posttensioning is significantly effective in improving the cracking resistance and seismic behavior, slowing down the stiffness degradation, as well as enhancing the shear and energy dissipation capacity of the PTCCM walls. The confinement effect provided by the ring beam and constructional columns can effectively improve the seismic behavior of the concrete masonry walls. By utilizing unbonded posttensioning, the ungrouted PTCCM walls had little residual deformation after cyclic loading. It can also be concluded that horizontal reinforced concrete strip can increase the cracking resistance, ductility and energy dissipation capacity of the walls. Based on the test results, a simple analysis method for predicting the shear strength of the PTCCM walls is proposed.

Keywords

Concrete masonry Posttensioning Shear strength Ungrouted Seismic behavior 

List of Symbols

\({A_{\text{c}}},{h_0}\)

The cross-section area and effective length of constructional columns (mm2, mm)

\({A_{\text{m}}},{f_{\text{v}}}\)

The cross-section area and shear strength of masonry walls (mm2, MPa)

\({A_{{\text{sv}}}},{f_{{\text{yv}}}}\)

The section areas and yield strength of stirrups (mm2, MPa)

\({f_1},{f_2}\)

The average compressive strengths of concrete blocks and mortar (MPa)

\({f_{\text{m}}},{f_{{\text{cu}}}}\)

The average compressive strengths of masonry prisms and concrete (MPa)

\({f_{{\text{vo}}}}\)

The average shear strength of masonry prisms in the absence of vertical compression stress (MPa)

\({P_{\text{c}}},{P_{\text{u}}}\)

The measured initial cracking strength and shear strength of test walls (KN)

\(s\)

The distance between stirrups (mm)

\({V_{\text{u}}}\)

The predicted ultimate shear strength of test walls (KN)

\({V_{\text{m}}},{V_{\text{c}}}\)

The shear capacities provided by masonry walls and constructional columns (KN)

\({\sigma _{{\text{s}}1}},{\sigma _{{\text{s}}2}}\)

The average yield strengths of PT tendons and longitudinal reinforcements (MPa)

\({\sigma _{\text{y}}}\)

Total axial compression stress of test walls (MPa)

\({\sigma _{\text{p}}}\)

Additional axial compression stress of test walls provided by posttensioning (MPa)

\({\zeta _{\text{p}}}\)

Effective coefficient to account for the contribution of PT tendons elongation in increasing the shear capacity of test walls (−)

\({\zeta _{\text{g}}}\)

Reduction coefficient to account for the insufficient development of the constructional columns (−)

\({\xi _{\text{e}}}\)

The equivalent viscous damping coefficient of test walls (−)

\({\Delta _{\text{c}}},{\Delta _{\text{y}}},{\Delta _{\text{u}}}\)

The cracking, equivalent yield and ultimate displacements of test walls (mm)

\({\gamma _{\text{u}}},{\mu}\)

The ultimate drift capacity and displacement ductility factor of test walls (−)

\(\alpha\)

Regression factor (−)

\({\mu _{\text{o}}}\)

The friction coefficient between mortar joints (−)

Notes

Acknowledgements

The research described here was supported by National Natural Science Foundation of China (Grant No. 50708045). The experiments were conducted at the Jiangsu Key Laboratory of Civil Engineering and Disaster Prevention and Mitigation. The authors wish to gratefully acknowledge the support of these organizations for this study.

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Copyright information

© Iran University of Science and Technology 2017

Authors and Affiliations

  • Zhanggen Guo
    • 1
    • 2
    Email author
  • Songlin Zheng
    • 1
  • Zhenwen Xu
    • 1
  • Weimin Sun
    • 1
  1. 1.College of Civil EngineeringNanjing Tech UniversityNanjingChina
  2. 2.Department of Civil and Environmental EngineeringUniversity of WashingtonSeattleUSA

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