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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 475 Abstracts search results
June 30, 2020
Royce Liu and Alessandro Palermo
Structural redundancy and robustness are necessary to protect against beyond design seismic loads. In this paper, the idea of improving these properties is applied to single column bridge piers using the hybrid PRESSS/Dissipative Controlled Rocking (DCR) system through a novel technique called hierarchical activation. This technique involves the inclusion of more “hinges” (rocking interfaces) and or sets of dissipative devices in such a way that they are activated in a hierarchy with respect to the displacement of the structure. A 2/3 scale cantilever column designed to use this technique was tested. The specimen was capable of multiple configurations, two of which are focused on in this paper: conventional DCR; and segmented DCR (segDCR), which used hierarchical activation. Hierarchical activation was successfully achieved in the experiment; and despite the global response being similar, segDCR was found to be advantageous with respect to reducing the cyclic strain demand on the dissipaters.
Maher AL-Hawarneh, AHM Muntasir Billah, and M. Shahria Alam
In recent years, shape memory alloys (SMA) have drawn significant attention and interests among researchers and structural engineers for diverse civil engineering applications. Superelasticity, shape memory effect, and hysteretic damping are the three major characteristics of SMAs that make them appropriate for bridge engineering applications in high seismic zones. Recent earthquake events have shown the most devastating earthquake loading that structures could experience are the near-fault ground motions. On the other hand, the ground motion duration effect on structural response has attracted a lot of interest over the last decade. This study aims to evaluate the comparative seismic fragility of concrete bridge piers reinforced with SMA rebars and steel rebars in the plastic hinge region under long duration and near-fault earthquakes. The bridge pier is assumed to be part of a lifeline bridge located in Western Canada and has been designed following a performance-based design approach. Fragility analysis has been conducted considering uncertainty in the material properties and the seismic hazard of the site location. Fragility curves are developed using suits of long duration and near-fault motions where each suite contains 20 ground motions. The vulnerability of the SMA-RC bridge piers and steel-RC bridge piers has been evaluated in terms of maximum drift and residual drift as the demand parameters. The outcome of this study indicates how the performance of the SMA-RC bridge pier and steel-RC bridge pier are affected by the duration of ground motion and fault location.
Arya Ebrahimpour and Barbara Earles
Accelerated Bridge Construction (ABC) technologies are being adopted by state transportation departments. One particular ABC technology is the use of precast concrete members joined with mechanical connectors. However, there are concerns about these connections in moderate-to-high seismic regions. A study was carried out for the Idaho Transportation Department (ITD) on the seismic performance of precast columns with grouted couplers versus the conventional cast-in-place columns. Experimental data provided the necessary input to model the grouted couplers. Using the OpenSees finite element analysis program, selected bridges were subjected to the seismic conditions of the most seismically active location in Idaho. Under seismic conditions considered, the stresses in both the longitudinal reinforcing bars and the grouted coupler regions are found to be well within acceptable ranges. The study resulted in recommendations on allowable column drifts, a list of approved grouted rebar couplers, and typical detail drawings for inclusion in the ITD’s Bridge Manual.
Mahmoud Aboukifa, Mohamed A. Moustafa and Ahmad Itani
Ultra-High Performance Concrete (UHPC) is a versatile building material as it is characterized by very high compressive strengths reaching 30 ksi [200 MPa], ductile tensile characteristics, and energy absorption. Currently, UHPC is commonly used in limited structural applications, such as joints and connections between precast structural elements. To extend the use of UHPC in full structural elements, a better understanding of the structural behavior and failure mechanism of such elements is needed. One potential application of UHPC for structural elements is columns, which is the focus of this study. This paper presents an experimental investigation of the behavior of UHPC column subjected to combined axial and lateral loading. A large-scale UHPC column is tested under axial and quasi-static cyclic lateral loading at the Earthquake Engineering Laboratory at the University of Nevada, Reno. To establish a comparison with conventional columns, a normal strength concrete (NSC) column with same dimensions and design as the tested UHPC column is analytically modeled and analyzed under similar loading protocol using OpenSEES. The experimental response of the UHPC column is evaluated and compared to the analytical response of the NSC column. Both global and local behavior are presented and discussed to include damage progression, failure type, peak moment strength, stiffness degradation, and displacement and curvature ductility.
Amer Hammoud and Hassan Aoude
This paper presents the results from tests examining the performance of high-strength concrete (HSC) and normal-strength concrete (NSC) columns subjected to blast loading. As part of the study six columns built with varying concrete strengths were tested under simulated blast loads using a shock-tube. In addition to the effect of concrete strength, the effects of longitudinal steel ratio and transverse steel detailing were also investigated. The experimental results demonstrate that the HSC and NSC columns showed similar blast performance in terms of overall displacement response, blast capacity, damage and failure mode. However, when considering the results at equivalent blasts, doubling the concrete strength from 40 MPa to 80 MPa (6 to 12 ksi) resulted in 10%-20% reductions in maximum displacements. On the other hand, increasing the longitudinal steel ratio from ρ = 1.7% to 3.4% was found to increase blast capacity, while also reducing maximum displacements by 40-50%. The results also show that decreasing the tie spacing (from d/2 to d/4, where d is the section depth) improved blast performance by reducing peak displacements by 20-40% at equivalent blasts. The use of seismic ties also prevented bar buckling and reduced the extent of damage at failure. As part of the analytical study the response of the HSC columns was predicted using single-degree-of-freedom (SDOF) analysis. The resistance functions were developed using dynamic material properties, sectional analysis and a lumped inelasticity approach. The SDOF procedure was able to predict the blast response of HSC columns with reasonable accuracy, with an average error of 14%. A numerical parametric study examining the effects of concrete strength, steel ratio and tie spacing in larger-scale columns with 350 mm x 350 mm (14 in. x 14 in.) section was also conducted. The results of the numerical study confirm the conclusions from the experiments but indicate the need for further blast research on the effect of transverse steel detailing in larger-scale HSC columns.
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