No abstract

A series of 10 reinforced concrete T‐beams, designed deficient in shear, were tested in order to investigate the shear performance achieved through externally applied U‐shaped FRP composite strips. Key variables of the study were: type of FRP composite, type of surface bonding and type of end anchorage for the strips. Carbon fibre‐reinforced polymer (CFRP), glass fibre‐reinforced polymer (GFRP) and high modulus of elasticity carbon fibre‐reinforced polymer (Hi‐CFRP) strips were the special composite types with different elastic moduli, full or partial bonding of the strips to the beam surface were the variables for the type of surface bonding. All partially bonded FRP strips were free from surface bonding, whereas epoxy‐bonded FRP anchors were used at their ends close to the slab‐to‐beam connection. Those strips with full surface bonding have either epoxy‐bonded FRP anchors at their ends or the strip ends were without anchorage. The test results revealed that shear‐deficient beams may well be strengthened by the externally applied FRP strips. However, the level of strength enhancement and the failure pattern is closely influenced by the composite's elastic modulus, the type of surface bonding and the type of end anchorage for the FRP strip itself. The enhancement of the Hi‐CFRP strips did not live up to expectations. The use of unbonded FRP for shear strengthening yielded promising results.

No abstract

A destructive earthquake, magnitude of Mw = 7·2 (Richter scale), hit the city of Van, located in eastern Turkey, on 23 October 2011 and another major earthquake with a magnitude of Mw = 5·6 occurred on 9 November 2011. Significant damage was observed in all types of civil engineering structures in the city centre and nearby. This paper presents the field observations on the seismic performance of precast concrete structures during the earthquakes. Possible damaging factors were discussed in detail after a comprehensive site survey. The majority of the investigated structures were industrial precast concrete structures located in the organised industrial zone of Van. In addition to industrial precast concrete structures, a precast multi-storey residential building located in the city centre was also examined. The findings from the site investigations were compared with the seismic behaviour of similar precast concrete structures during the former devastating earthquake in north-western Turkey in 1999. The effects of improper design and detailing of precast connections during the construction of the precast concrete structures in the high-seismicity regions are reported.

Abstract. This study is part of a research program within the framework of NATO Project 977231 "Seismic Assessment and Rehabilitation of Existing Buildings" led by METU. A new seismic retrofitting method by using CFRP cross overlays is experimentally investigated. Five specimens were tested to highlight the effect of brick infill and epoxy bonded CFRP overlays on the strength and behavior of poorly detailed reinforced concrete frames. The main deficiencies of the one-third scale one-bay, two-story frames tested were low concrete strength, insufficient column lap splice length, poor confinement, and inadequate anchorage length of beam bottom reinforcement. In all specimens beams were stronger than columns and no joint shear reinforcement was used.