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This paper looks at the use of fiber reinforced polymer (FRP) reinforcement in concrete columns, for use in new construction. The state-of-the-art on FRP reinforced concrete (RC) columns is presented with a brief discussion of research findings. The behavior of columns as well as FRP reinforcement in compression is included. The use of FRP transverse reinforcement is discussed in terms of its effectiveness as confinement reinforcement. The paper also includes a summary of an experimental study of FRP RC columns currently being conducted at the University of Ottawa. Details of the test program, as well as test results, are given. Results indicate that FRP reinforcement can be effectively used in new concrete columns. The use of FRP transverse reinforcement in columns was also investigated experimentally and analytically. Carbon FRP grids were used as column confinement reinforcement. Test results indicate that these grids, with relatively lower elastic modulus as compared to steel of equivalent volumetric ratio, were able to confine concrete effectively and improve column inelastic drift capacity. Columns with CFRP grids showed lateral drift capacities of from 4-6%, depending on the grid size and the number of grid cells.
Recent bomb attacks on buildings have raised awareness about the vulnerability of structures to blast effects. The resiliency of structures against blast-induced impulsive loads is affected by structural characteristics that are also important for seismic resistance. Deformability and continuity of structural elements, strength, stiffness, and stability of the structural framing system and resistance to progressive collapse are factors that play important roles on the survivability of buildings under both blast and seismic loads. The significance of these structural parameters on blast resistance of reinforced concrete buildings is assessed through structural analysis. Both local element performance and global structural response are considered while also assessing the progressive collapse potential. The buildings under investigation include 10-storey moment resisting frames with or without shear walls. The blast loads selected consist of different charge-weight and standoff distance combinations. The results are presented in terms of ductility and drift demands. They indicate improved performance of seismic-resistant buildings when subjected to blast loads, in terms of local column performance, overall structural response, and progressive collapse potential.
Two discussions of a paper with the aforementioned title by J. Hoshikuma, K. Kawashima, K. Nagaya, and A.W. Taylor, published in this journal (Volume 123, Number 5, May 1997), are presented. The first discusser presents a model that he proposed in 1991, which was developed on the basis of a large database including 63 column specimens with rectangular hoops from five different experimental programs. He also proposes that the effect of hook shape, the relationship between the strength of the unconfined specimens the authors tested to the cylinder strength, and the possible effect of longitudinal reinforcement warrant further investigation. The last two discussers present eight points that they believe deserve further attention before the authors' approach for confined concrete columns can be utilized. Discussions are followed by closure from the authors.
Abstract As aging infrastructures raise public concerns, evaluating their performance is crucial for maintaining structural integrity, especially for corroding prestressed concrete members. These structures may experience substantial tendon cross‐sectional area loss before any visible deterioration becomes detectable. While various non‐destructive techniques (NDT) have proven effective in labs, correlating corrosion‐induced damage in field members remains a challenge. Establishing these correlations is key for understanding the overall performance of aging structural concrete elements and ensuring their continued safe operation through non‐invasive means. This paper investigates various NDTs on a concrete bridge deck, aiming to correlate results. Visual inspection, Schmidt rebound hammer, Ultrasonic Pulse Velocity (UPV), corrosion detection techniques, Ground Penetrating Radar (GPR), Ultrasonic Pulse Echo (UPE), and Impact Echo (IE) methods are evaluated for detecting concrete deck damage. Results show the methods' capabilities in detecting defects to a certain extent, highlighting their potential in assessing aging concrete infrastructures.
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Fragility analysis was conducted for reinforced concrete frame buildings in Canada designed based on the 1965 National Building Code of Canada as representative of pre-1975 era of seismic design practice. Two-, five-, and ten-storey buildings were designed for Vancouver and Ottawa, representing buildings in high and medium seismic regions. They were modelled for inelastic response time history analysis, with respective inelastic hysteretic models for flexure and shear. Software PERFORM-3D was used to conduct incremental dynamic analysis under incrementally increasing earthquake intensity. Probabilistic analysis of the results of incremental dynamic analysis led to the development of fragility functions, which can be used as seismic vulnerability assessment tools. The results are compared with those generated for frame buildings designed on the basis of the 2010 NBCC. The comparison indicates that the probabilities of exceeding performance levels are significantly higher for older buildings relative to recently built fully ductile and moderately ductile buildings, respectively.
Masonry infill walls are often used as non-structural elements. According to the past structural failure, ignorance of interaction between infill walls and enclosed frame may lead to the different seismic response for non-ductile building frames. The main contribution of this paper is to analytically investigate the behavior of reinforced concrete with masonry infill panels as participating structural. In doing so, a finite element model based on an equivalent strut method is conducted to represent the behavior of masonry panels. The strut model is calibrated using the results of the companion experimental program, which examined the cyclic behavior of infill panels with and without FRP sheets. Accordingly, a nonlinear spring element and a shell element are used to simulate the behavior of masonry strut elements and FRP sheets, respectively. The nonlinear static analysis (Push over analysis) is accomplished using SAP2000 [1] structural analysis software for a 10-story building with FRP sheets subjec
The corrosion of steel reinforcement in concrete and the resulting deterioration of structures prompted research on fiber reinforced polymers (FRP) as potential reinforcement for concrete members, for use in new construction. FRPs have more favorable advantages for new concrete buildings subjected to seismic loads particularly in corrosive environment. A comprehensive experimental research program was conducted at Ottawa University in Canada to investigate the behavior of FRP reinforced concrete joints to develop design and detailing requirements for FRP reinforced concrete joints under seismic loading. Three large-scale FRP reinforced concrete structural joints were designed, constructed, and tested under cyclic loading. The specimens were T-shape joints consisting of two columns and one beam representing half portion of the first and the second floor of one-bay reinforced concrete frame, or exterior joint of frames with more than one bay. The columns were subjected to the constant axial load and the beams were under reversed cyclic loading. The reinforcement cage was consisted of CFRP bars as longitudinal reinforcement and CFRP grids as transverse reinforcement. The paper presents the details and results of the experimental programs. The results indicate that FRP reinforcement can be used effectively in new concrete buildings. Photographs taken at the selected stages of loading illustrated the performance of each joint. The hysteretic behavior was presented in terms of force–displacement and moment–drift relationships and other hysteretic relationships. Spacing of CFRP grids and arrangement of longitudinal CFRP bars were the main test parameters.
The 1975 Turkish code provisions are first reviewed to provide the background for design and detailing of structures prior to the earthquake. The performance of reinforced concrete and masonry structures is described indicating many of the deficiencies in design, detailing, and construction execution. The behaviour of precast concrete structures, steel structures, and industrial facilities is also presented. The provisions of the 1997 Turkish building code are summarized and a description of new construction provides evidence of both excellent and poor construction practice. Some examples of retrofitting of damaged structures soon after the earthquake are also presented.Key words: seismic design, earthquake, Kocaeli, structures, codes, concrete, precast concrete.
This paper consists of reported information divided into two general categories, performance of High-Strength Concrete (HSC) columns under concentric loads, and combined axial and bending moments. Presented is a brief summary of the highlights of the reported data.
Masonry infill walls are often used as non-structural elements. According to the past structural failure, ignorance of interaction between infill walls and enclosed frame may lead to the different seismic response for non-ductile building frames. The main contribution of this paper is to analytically investigate the behavior of reinforced concrete with masonry infill panels as participating structural. In doing so, a finite element model based on an equivalent strut method is conducted to represent the behavior of masonry panels. The strut model is calibrated using the results of the companion experimental program, which examined the cyclic behavior of infill panels with and without FRP sheets. Accordingly, a nonlinear spring element and a shell element are used to simulate the behavior of masonry strut elements and FRP sheets, respectively. The nonlinear static analysis (Push over analysis) is accomplished using SAP2000 [1] structural analysis software for a 10-story building with FRP sheets subjec
The selection of seismic motions is one of the most important issues for the time-history analysis of buildings. This paper discusses four different methods for obtaining spectrum-compatible acceleration time histories (i.e., accelerograms) of seismic motions. Based on these methods, four sets of accelerograms compatible with the design spectrum for Vancouver were selected for this study. These included (i) scaled real accelerograms, (ii) modified real accelerograms, (iii) simulated accelerograms, and (iv) artificial accelerograms. The selected sets were used as excitation motions in the nonlinear analysis of three reinforced concrete frame buildings designed for Vancouver. The buildings included a 4-storey, a 10-storey, and a 16-storey building, which can be considered representative of low-rise, medium-rise, and high-rise buildings, respectively. The storey shears, interstorey drifts, and curvature ductilities for beams and columns obtained from the analysis were used for the evaluation of the effects of the selected sets on the responses of the buildings. Based on the results from the analysis, scaled real accelerograms are recommended for use in time-history analysis of reinforced concrete frame buildings.
A reconnaissance was conducted in Indonesia to investigate the effects of the 26 December 2004 earthquake and tsunami on buildings, bridges, and other physical infrastructure. The infrastructure in the coastal regions of Banda Aceh was completely devastated by both tsunami wave pressures and seismic ground excitations. The damaging effects of the tsunami were most pronounced in unreinforced masonry walls, nonengineered reinforced concrete buildings, and low-rise timber-framed buildings. Engineered structures survived the tsunami pressure, but many suffered extensive damage due to seismic forces. The majority of the seismic damage was attributed to poor design and detailing of nonductile buildings. Specific observations made during the reconnaissance indicate the engineering significance of the disaster.
