Distress Evaluation and Remediation for a High-Rise Building with Pile-Raft Foundation.

A high-rise building with pile-raft foundation suddenly experienced extraordinary settlements and seriously tilted after 6 years of use in Wenzhou, a city in southeastern China. Some investigations were conducted and several potential causal factors were analyzed to determine the cause of the distress. The results indicated that the inadequate bearing capacity of the pile foundation was the reason for the extraordinary settlement. Inappropriate structure type selection and structural arrangement made the building sensitive to earthquake-triggered loading and prone to tilt. Remedial measures were applied to address the causal factors identified. Because of the low bearing capacity of the pile foundation, unloading was first performed and then the pile foundation was strengthened using steel pipe piles driven by anchor bolts. To address the inappropriate structure type and arrangement, the building was retrofitted to resist earthquakes. Observation results showed that the remedial measures took effect and the settlement (and tilt) of the building was completely controlled. [ABSTRACT FROM AUTHOR]