Some Issues in the Seismic Assessment of Shear-Wall Buildings through Code-Compliant Dynamic Analyses

Abstract

Due to their excellent seismic behavior, shear wall-type concrete buildings are very popular in earthquake-prone countries like Chile. According to current seismic regulations, the performance of such structures can be indifferently assessed through linear or non-linear methods of analysis. Although all the code-compliant approaches supposedly lead to a safe design, linear approaches may be in fact less precise for catching the actual seismic performance of ductile and dissipative structures, which can even result in unconservative design where comparatively stiff buildings like reinforced-concrete shear-wall (RC-SW) buildings are concerned. By referring to a mid-rise multistory RC-SW building built in Chile and designed according to the current seismic Chilean code, the paper investigates the effectiveness of the linear dynamic analyses to predict the seismic performance of such kind of structures. The findings show that the code-compliant linear approaches (Modal Response Spectrum Analysis and Linear Time-History Analysis) may significantly underestimate the displacement demand in RC-SW buildings. This is highlighted by the comparison with the results obtained from the Non-Linear Time-History Analysis, which is expected to give more realistic results. A set of ten spectrum-consistent Chilean earthquakes was considered to carry out the time-history analyses while a distributed-plasticity fiber-based approach was adopted to model the non-linear behavior of the considered building. The paper highlights how the risk of an unsafe design may become higher when reference is made to the Chilean code, the latter considering only the Modal Response Spectrum Analysis (MRSA) without even providing corrective factors to estimate the inelastic displacement demand. The paper checks the effectiveness of some amplifying factors taken from the literature with reference to the case-study shear-wall building, concluding that they are not effective enough. The paper also warns against the danger of local soft-story collapse mechanisms, which are typical of reinforced concrete frames but may also affect RC-SW buildings when weaker structural parts made by column-like walls are present at the ground floor.

Comparative Assessment of Performance-Based Design Methodologies Applied to a R.C. Shear-Wall Building

“…Based on this, a comparison of material volumes and weights is presented in Table 10, using the actual volume of the FBD structure and an approximate estimation for the PBD structure. The increase in the quantity of materials achieved by applying PBD in accordance with Chilean provisions is in line with the findings of a previous study [66], in which the cost difference between FBD and PBD amounted to only 2% of the cost of the superstructure of the building.…”

A Contribution to Facilitate the Seismic Design in Lebanon Using Short-Length Spectrum-Consistent Earthquakes

“…Figure 13a presents the results obtained for the maximum roof displacements. It is noteworthy that the values of displacements calculated through LTHAs are higher than those obtained through MRSAs, which is typical when comparing these two types of analyses [8]. Similarly, the results of the maximum calculated values of base shear forces for the seven accelerograms compatible with EC8 spectra are shown in Figure 13b.…”

“…On the other hand, a database of recorded ground motions should be at researcher's disposal to obtain suitable suites of synthetic SCEs. Inconsistencies in codes in the definition of DRS [8,9], as well as unavailability of suitable seismic records for the dynamic analyses are some of the obstacles that may compromise the seismic design/assessment of buildings.…”

Evaluating Seismic Performance in Reinforced Concrete Buildings with Complex Shear Walls: A Focus on a Residential Case in Chile

“…Modern seismic codes, which try to reflect great advances in knowledge and understanding in a very simple way, are not transparent about the expected level of behavior or response of the complete system [26][27][28][29][30]. For this reason, it is necessary to implement a structural design and analysis methodology that allows us to achieve a deeper understanding of the problem of seismic-resistant design, considering the inelastic behavior of R.C.…”