This study investigates the feasibility of the application of ultrasonic measurement to characterize Steel-Fiber-Reinforced Concrete (SFRC) Specifically, the effects of steel fiber content, age, moisture content, and fiber orientation on Ultrasonic-Pulse-Velocity (UPV) were investigated In this regard, beam and cylindrical samples were fabricated with different steel fiber contents The result indicated that for beam specimens the UPV increases with the addition of fiber up to 2% and decreases for higher fiber percentages Additionally, the fiber orientation within the beam specimens influences the UPV measurements For cylindrical samples, the rate of UPV decreased with the addition of steel fiber reinforcement In addition, it was discovered that the curing period affects the magnitude of UPV

/pdf/application-of-ultrasonic-measurements-for-the-evaluation-of-2y5t95z1vl.pdf

Application of Ultrasonic Measurements for the Evaluation of Steel Fiber Reinforced Concrete

Seismic analysis and risk assessment of safety-critical infrastructure like hospitals, nuclear power plants, dams, and facilities handling radioactive materials involve computationally intensive nu...

https://www.tandfonline.com/doi/pdf/10.1080/00295450.2020.1807282

MASTODON: An Open-Source Software for Seismic Analysis and Risk Assessment of Critical Infrastructure

Industrialized societies depend on the proper functioning of a whole range of technological infrastructures, such as electricity, road and railway networks and telecommunications which, due to their importance, are generically referred to as critical infrastructures (CIs). Technical failures, natural disasters and malicious events, if not terrorist, could have devastating effects on these infrastructures. The events of the last few years have accelerated efforts to identify and designate CIs at national and European levels and have reinforced concerns about increasing their protection in sensitive sectors for the safety of the individual and the community. The aim of this research is to provide the basic elements to understand the issue along with the reasons for its importance both at national, European and international level. In particular, after analyzing the origin of the problem, a systematic literature review is carried out to study the current research around future perspectives relating to the management of Cis, with particular focus on three research questions: RQ1 “What types of risk assessment methods are used to manage CIs?”, RQ2 “What are the environmental risk mitigation strategies for CIs?” and RQ3 “What is the role of the human factor in the prevention of risks for CIs?”. The results aim to be guidelines for decision makers and researchers interested in this topic. 

/pdf/critical-infrastructures-overview-past-present-and-future-14aa3f03.pdf

Critical Infrastructures Overview: Past, Present and Future

The acoustic fluid‐structure interaction (FSI) formulation is a practical numerical approach for the seismic analysis of fluid‐filled tanks. However, there are no verification and validation studies reported in the literature that demonstrate the ability of an acoustic FSI numerical model to predict responses important to structural and mechanical design for intense translational and rotational earthquake inputs. Herein, an acoustic FSI formulation is implemented in the open‐source Multiphysics Object‐Oriented Simulation Environment (MOOSE), and is formally verified and validated using analytical solutions and code‐to‐code verification, and experimental data, respectively. The analytical solutions are for small amplitude, unidirectional seismic inputs. The code‐to‐code verification utilizes a previously verified and validated Arbitrary Lagrangian‐Eulerian (ALE) numerical model in the commercial finite element code LS‐DYNA. The validation studies utilize a comprehensive data set assembled from results of 3D earthquake‐simulator tests of a fluid‐filled vessel. The acoustic numerical model in MOOSE is verified and validated for hydrodynamic pressures and support reactions except for cases that involve significant convective response. For small amplitude inputs, numerically predicted wave heights match those of the analytical solutions. The numerical model is not verified and validated for wave height calculations under intense 3D seismic inputs. The run times for the acoustic FSI simulations in MOOSE are an order of magnitude, or more, shorter than for the corresponding ALE simulations in LS‐DYNA. The utility of the MOOSE acoustic FSI implementation is demonstrated by seismic analysis of a building equipped with a fluid‐filled, advanced nuclear reactor.

Development, verification, and validation of comprehensive acoustic fluid‐structure interaction capabilities in an open‐source computational platform

Due to seismic response, accumulation of permanent ground deformation (lateral spreading) is an important mechanism of much practical significance. Such deformations typically occur near a ground s...

Asymmetric input motion for accumulation of lateral ground deformation in laminar container shake table testing

Dynamic ground and ground-structure responses are heavily dependent on the soil shear wave velocity. During seismic excitation, soil stiffness inferred from the shear wave velocity (Vs) might change significantly and affect the overall system response. In this study, an instrumentation and analysis framework was developed to allow for continuous estimation of Vs during dynamic/seismic excitation. The framework is presented along with representative applications during shake table testing of saturated sand strata. For that purpose, results from two different 1-g shake table tests conducted in a laminar soil container are examined and analyzed. In this context, evolution of the soil Vs profile during the shaking event is tracked and documented. The experimental setup, test procedure, and test results are described. Time histories of Vs at different depths within the sand strata are discussed. Overall, the developed techniques can be conveniently included in routine 1-g and centrifuge shake table experimentation efforts, when properly accounting for the differences between sizes of 1 g and centrifuge models.

Shake Table Testing: A High-Resolution Vertical Accelerometer Array for Tracking Shear Wave Velocity

Polymer Injection and Liquefaction-Induced Foundation Settlement: A Shake Table Test Investigation

For large embedded structures, soil-structure interaction (SSI) plays a major role in dictating the overall seismic response. In light of recent strong seismic excitation affecting such str...

Three-Dimensional Seismic Response of a Large Embedded Structure and Induced Earth Pressure

Currently, the knowledge base and quantitative data sets concerning cut and cover tunnel seismic response are scarce. In this report, a large-scale experimental program is conducted to assess: i) stiffness, capacity, and potential seismically-induced nonlinear deformation mechanisms of a representative reinforced concrete tunnel liner, and ii) seismic demand as dictated by the surrounding soil and the tunnel-ground interaction mechanisms. In this regard, the conducted testing efforts allow for more accurate representation of the tunnel reinforced concrete liner configuration, and for use of field soil materials and construction procedures. Based on the recorded experimental data sets, computational studies are performed to further assess the involved soil-structure-interaction mechanisms. Overall, these studies constitute an initial important step towards ultimately providing experimentally validated engineering procedures for use in the development of cut and cover tunnel seismic assessments and design guidelines.

Kyungtae Kim

Papers

MASTODON: An Open-Source Software for Seismic Analysis and Risk Assessment of Critical Infrastructure

Shake Table Testing: A High-Resolution Vertical Accelerometer Array for Tracking Shear Wave Velocity

Polymer Injection and Liquefaction-Induced Foundation Settlement: A Shake Table Test Investigation

Three-Dimensional Seismic Response of a Large Embedded Structure and Induced Earth Pressure

Racking Response of Reinforced Concrete Cut and Cover Tunnel