This Week's Featured Presentation
Effects of Extreme Events on Reinforced Concrete Columns (ACI Spring 2019 Convention, Québec City, QC, Canada) Concrete-filled fiber reinforced polymer (FRP) tubes (CFFT) have a superior resistance to harsh environmental conditions. In addition, the FRP tube considers a noncorrosive reinforcement and protects the concrete core against severe environmental conditions. The composite action has a significant effect on the flexural behavior of any composite structural element. The bond between the FRP tube and the concrete core reflects the degree of composite action between them. This case study presents an experimental investigation, which uses a new technique to evaluate the bond between the FRP tube and the concrete core. This technique depends on using internal strain gauges inside the concrete core and comparing the measured strains with the corresponding strains on the external tube surface. Full composite action means that the strain distribution is linear over the cross section (plane sections remain plane) and the internal concrete strain is equal to the external strain on the tube surface at the same position. Two full scale columns with different diameters 305 mm (12 inch) and 406 mm (16 inch) were tested under lateral cyclic load. These columns are connected to rigid reinforced concrete (RC) footings. The experimental results indicate that the composite action was achieved at the beginning of the test, then the failure of the bond between the concrete core and the tube occurred. After the bond failure, the tube and the concrete core were working individually.
November 18 – 24
Comparison of Damage Mechanisms of CFRP-Strengthened Reinforced Concrete Columns Subjected to Blast, Impact, and Quasi-Static Loads
by Husham Almansour, National Research Council Canada
Effects of Extreme Events on Reinforced Concrete Columns (ACI Spring 2019 Convention, Québec City, QC, Canada) The dramatic global terrorist events that occurred in recent years in which large number of critical structures have been targeted raised the need among the structural engineering community to better understand the performance of reinforced concrete buildings when exposed to blast or high-speed impact threats. Columns are the most critical elements in structural systems and mainly designed to resist gravity loads and in most buildings the effect of blast and impact loads are not considered in the design stage. However, the failure of a column during an explosion event or a high-speed mass attack could lead to a progressive collapse of the entire structure. In this study, the effects of blast and hard-surface impact loads on the structural performance, damage and failure mechanisms of RC columns are investigated. Several half-scale column specimens are tested under blast or impact loads using shock tube and impact loading system. On the other hand, similar specimens are tested under uniformly distributed or concentrated quasi-static loads with boundary conditions similar to those specimens tested under dynamic loads. Some of the specimens are non-strengthened while others are strengthened by CFRP laminates. The stages of damage mechanisms, load deformations and other structural performance relationships are to be investigated and reported.