Cyclic behavior of thin RC Peruvian shear walls: Full-scale experimental investigation and numerical simulation
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 (hw/lw) 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.
References (25)
Strength and deformation of mid-rise shear walls under load reversal
Eng Struct
(2000)- et al.
Cyclic behaviour of a full scale RC structural wall
Eng Struct
(2003) - et al.
Influence of diagonal web reinforcement on cyclic behavior of structural walls
Eng Struct
(2007) - et al.
Probabilistic seismic demand analysis of a slender RC shear wall considering soil-structure interaction effects
Eng Struct
(2011) - et al.
Seismic performance of buildings with thin RC bearing walls
Eng Struct
(2012) Experimental shear dominated response of RC wall. Par II: discussion of results and design implication
Eng Struct
(2001)- EERI, 2010. The Mw 8.8 Chile Earthquake of February 27, 2010. Special Earthquake Report – June...
- Gálvez V, Burgos M, Ortiz A. Proposal of reduction factor for seismic forces in structural systems composed by walls...
- Ministry of Housing Peru. National technical standard E-030 – earthquake resistant design, Lima, Peru; 2003 [in...
- Ministry of Housing Peru. National technical standard E-060 – reinforced concrete design, Lima, Peru; 2009 [in...
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
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