Previous works on the earthquakes indicated regular behavior of reinforced concrete buildings with structural walls. However, this latest investigation has revealed that some buildings suffered significant damage associated with global or local collapse due to diagonal cracking and flexural-compression failure.
Structural walls located at the ground floor presented tension-compression failure, which was probably provoked by high axial forces at the walls’ extreme ends, which lack bracing and confinement.
In New Zealand, the structures analyzed were the CTV Building, Pyne Gould Corporation Building, Grand Chancellor Hotel and the Forsyth Barr Building. All were affected by high ground accelerations of 2.2g. The New Zealand Construction Code used in these building did not include the concept of ductility, so the spectral acceleration was, therefore, lower.
In Chile, the structures analyzed suffer from flexural compression failure. Tension compression failure provoked buckling of the transversal wall (where the main bars presented lack of seismic hooks), deficient reinforcement due to small bar diameters and large spaces between the transversal reinforcement. Plan and elevation irregularities were also identified as factors that caused the structures to fail and collapse.
In order to avoid these problems in the future, the researchers recommended greater consideration of the following factors in future designs and constructions:
- Re-evaluation of the seismic hazard coefficient
- Adding reinforcing steels in wall
- The optimal length of seismic hooks, structural walls and different thickness levels (higher than 200 mm)
This research is reported in the article “Main Reasons of Structural Wall Collapse in Chile 2010 and New Zealand 2011 – Implications for Ecuador” in The Open Civil Engineering Journal.
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