Cyclic behavior of thin RC Peruvian shear walls: Full-scale experimental investigation and numerical simulation

doi:10.1016/j.engstruct.2013.02.033

Engineering Structures

Volume 52, July 2013, Pages 153-167

https://doi.org/10.1016/j.engstruct.2013.02.033 Get rights and content

Highlights

•
The experimental results of seven full-scale thin RC shear walls are presented.
•
The parameters to define the Three-parameter Park hysteretic model were estimated.
•
The results of the numerical simulation are in good agreement with test results.
•
The calibrated model will be used to develop fragility curves in a future study.

Abstract

The experimental results of seven full-scale thin RC shear walls subjected to cycling loading are presented. The objective of these experiments is to evaluate the use of electro-welded wire mesh as the main reinforcement instead of a conventional reinforcement. Six walls are equipped with the electro-welded wire mesh, which is made of a non-ductile material, and one wall is reinforced with conventional bars, which are made of a ductile material. A single layer of main reinforcement is used in both directions. The edges of all walls are reinforced with conventional bars. These walls are widely used in low- and mid-rise buildings in central Peru, especially in Lima City. The structural behaviors are examined in terms of strength, stiffness, dissipated energy, and equivalent viscous damping. Finally, the “Three-parameter Park hysteretic model” is calibrated in order to reproduce the behaviors of the thin walls reinforced with the conventional reinforcement and electro welded-wire mesh. The parameters are applied to the results of the other walls reinforced by the electro-welded wire mesh. The results of numerical simulations are in good agreement with experimental results.

Introduction

Shear walls are an important aspect of buildings. They brace structures against lateral forces such as those generated by wind or earthquakes. The shear wall will experience inelastic deformations usually at the base of the wall during a strong earthquake. These inelastic deformations are beneficial to structures from an economic point of view. If we want to keep the structures with only elastic deformations at the occurrence of an earthquake, the cost would be increased.

During the last big earthquake in Latin America, the 2010 Chile earthquake, some buildings whose resistance systems to lateral loads were thin walls suffered from severe damage and in some cases collapsed [1]. In Peru, especially in Lima City, many similar types of buildings have been built since 2000, and the number of these types of buildings being constructed has been increasing over the years. However, Lima City has not been hit by a big earthquake since 1974. Therefore, it is difficult to know the behaviors of these buildings during seismic events.

In 1998, a group of engineers in Peru initiated a monotonic and cyclical testing program for thin walls with nominal strength to a compression of 9.81 MPa (100 kgf/cm²) for structural concrete. At that time, these thin walls were used in one- or two-story buildings, with vertical and horizontal reinforcements below the minimum specified in the Peruvian design code for structural walls [2].

In 1999, the first apartment building with more than three stories was designed and constructed in the Miraflores district, Lima, Peru. Materials Bank (BANMAT) promoted this project in order to relieve the slumming of land. From 2001 to 2005, other companies supported new investigations on this system. Those investigations were developed by both the Japan-Peru Center for Earthquake Engineering Research and Disaster Mitigation (CISMID) of the National University of Engineering (UNI) and the Pontifical Catholic University of Peru (PUCP). These investigations were directed at evaluating the impact in the capacity curves of the differences in stress–strain curves of ductile bars and an electro-welded wire mesh. They also evaluated the implications of the absence of confinement at the edges of the walls owing to their small thicknesses. With the results of these studies, some changes were made on standards E.030 [3] and E.060 [4] that incorporated specific articles on these types of walls called “limited ductility walls.” Both CISMID and PUCP subsequently continued the research to evaluate the use of electro-welded wire mesh as reinforcement of these walls.

A way to understand the behavior of an element or entire structure is through experimentation. In 1995, Pilakoutas and Elnashai studied the cyclic behavior of reinforced concrete cantilever walls [5] and compared the experimental results with analytical solutions with respect to stiffness characteristics, limit states, and deformational characteristics [6]. Tasnimi [7] analyzed the experimental results of four structural shear walls of conventional constructions subjected to cyclic lateral displacement. The results were analyzed in terms of cracking, strength degradation, deformation, stiffness, and ductility. Riva et al. [8] analyzed the results of an experimental test on a full-scale RC structural wall subjected to cyclic loading. In the studies previously mentioned, the arrangement of the main reinforcement was horizontal and vertical. Shaingchin et al. [9] studied the influence of web diagonal reinforcement on the cyclic behavior of structural walls. Most of these studies refer to the use of conventional bars as the main reinforcement and changing the amount or arrangement, but information on the use of electro-welded wire mesh in structural walls is limited. Tang and Zhang [10] developed a numerical model of a generic RC shear wall and foundation considering the nonlinear behaviors of the shear wall and the foundation response. Gonzales and López-Almansa [11] evaluated seismic performance of seven existing representative thin shear–wall and mid-height buildings located in Peru performing static and dynamic nonlinear response analyses.

In the present paper, the results of experiments carried out at CISMID in 2004 [12] will be investigated in detail by numerical simulation. Based on the experimental results, the “Three-parameter Park hysteretic model” is calibrated and validation of the numerical simulation is discussed. The walls employed in this study are the typical type of walls used in Peruvian buildings.

Section snippets

Description of the full-scale experiment

In 2004, a series of experiments were carried out on the thin walls with identical dimensions but with different amounts and types of reinforcement. The walls were cast at full scale with constant thickness and their height-to-length (h_w/l_w) ratio was set to 0.91. These walls were subjected to slow cyclic horizontal loading. The responses of seven walls were studied in terms of elastic stiffness and maximum strength [12].

Load–displacement diagrams

The relationships between the applied load and displacement at the top of the wall are shown in Fig. 4. The displacement was recorded by LVDT-5 shown in Fig. 3a.

Although the walls of Group A, MQE188EP-01 and MQE188EP-02, have the same dimensions and reinforcement, their hysteretic curves are slightly different. The hysteretic curve observed for the wall MQE188EP-02 exhibits more pinching and unloading stiffness degradation than that for the wall MQE188EP-01. In the case of Group B, MQE257EP-01

Maximum strength of the walls

The maximum strengths are estimated from the experiments as the peak lateral loads from the hysteretic curves. A summary of these results is shown in Table 5. Fig. 6a shows the skeleton curves estimated from the experimental results for all walls. The behaviors of the walls in the elastic range are similar, but they show slightly different responses in the inelastic range. The walls reinforced with the mesh QE188 exhibit the lowest maximum strength, and the walls reinforced with the

Calibration of Three-parameter Park hysteretic model

The experimental program provided the responses of typical thin RC shear walls that are used in low- and mid-rise buildings in central Peru. Numerical models of these walls are prepared and calibrated using experimental results in this chapter. The nonlinear material response is one of the causes of energy dissipation in hysteretic cycles. Numerical models are prepared in the program IDARC 2D version 7 [20]. The Three-parameter Park hysteretic model is used in order to simulate the nonlinear

Summary and conclusions

The results of static cyclic tests of seven full-scale thin RC shear walls carried out at CISMID were presented. The parameters to define the Three-parameter Park hysteretic model were estimated and validated using the hysteretic curves and characteristics of the responses. From the analysis of test results and the process of calibration and validation, the following conclusions can be drawn:

Although the walls have different main reinforcement, most of the curves show a similar tendency in

Acknowledgments

The authors would like to express their sincere gratitude to the Japan Science and Technology Agency (JST) and Japan International Cooperation Agency (JICA) under the SATREPS project “Enhancement of earthquake and tsunami disaster mitigation technology in Peru” and to the anonymous reviewers who made valuable suggestions to increase the technical quality of the paper.

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View full text

Cyclic behavior of thin RC Peruvian shear walls: Full-scale experimental investigation and numerical simulation

Highlights

Abstract

Introduction

Section snippets

Description of the full-scale experiment

Load–displacement diagrams

Maximum strength of the walls

Calibration of Three-parameter Park hysteretic model

Summary and conclusions

Acknowledgments

Eng Struct

Eng Struct

Eng Struct

Eng Struct

Eng Struct

Eng Struct

Cyclic behavior of RC cantilever walls, part I: experimental results

ACI Struct J

Cyclic behavior of RC cantilever walls, part II: discussions and theoretical comparisons

ACI Struct J