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This paper focuses on the dynamics of a submerged compound pendulum (SCP). The considered pendulum consists of a horizontal cylindrical element at its lowermost portion and a plate between the cylindrical element and the pivot. An approximate analytical expression for the natural frequency of the submerged compound pendulum is proposed. Further, a two-dimensional (2D) numerical model of the pendulum is developed using ANSYS (FLUENT). The natural periods of the SCP are determined for different geometric configurations. The analytically estimated natural periods of the pendulum match well with those obtained from numerical simulation. [ABSTRACT FROM AUTHOR]

In a laterally excited, partially liquid-filled U-shaped container, oscillation is the predominant motion of the liquid. However, there would be some sloshing in the liquid free surface at the vertical limbs of the container. Due to the presence of high-energy velocity pulses, near-fault ground motions can cause significant sloshing in the vertical limbs of the container. Thus, it is necessary to examine the effect of near-fault earthquake excitations on the sloshing liquid height, sloshing-induced hydrodynamic pressure, and shear stress at the walls of the U-shaped containers. The same is attempted in this paper. The standard "k-epsilon" turbulence model with enhanced wall function is considered in this study. The outcome of this study reveals that the time-wise frequency variation of the near-fault ground motions significantly affects the sloshing response of the liquid stored in the U-shaped containers. It is observed that the sloshing-induced hydrodynamic pressure is severely influenced by the frequency content of the ground motion records rather than their peak ground acceleration. [ABSTRACT FROM AUTHOR]

Bamboo has been used in various civil engineering applications for several decades, but its use as a substitute for steel in reinforced concrete is still in the nascent stage. Because the properties of bamboo differ both interspecies and intraspecies, a bamboo-reinforced concrete (BRC) member has a larger uncertainty than a steel-reinforced concrete member. Further, bamboo possesses comparatively lower bond strength than steel embedded in concrete. The bond properties have a significant impact on the behavior of BRC beams, especially the displacement response. Therefore, it is essential to characterize the bond properties between bamboo and concrete before designing a BRC beam. In this work, the bond properties are experimentally characterized first through a series of pullout tests. The average bond strength was found to be 2.41 MPa with a standard deviation of 0.4 MPa. Statistical analysis of the experimental findings suggests that the bond strength followed a lognormal distribution. Subsequently, a finite-element model for the pullout tests was developed by utilizing a surface-based cohesive interaction. Our numerical results agreed with the experimental results. By treating the bond stress as a random quantity in the numerical model, 81% of the experimental results were captured. Finally, a finite-element model of a BRC beam was developed, whose results agreed well with the experimental ones. Our experimental results and numerical models may be adopted for creating a rational design framework for BRC members. [ABSTRACT FROM AUTHOR]

The assessment of response of an aged concrete dam is important for the prediction of its behavior during earthquakes, so that remedial measures can be taken at the right time to withstand future earthquakes. The assessment is necessary, since the analyses procedures may become obsolete and the state of the art may change as the time of construction and the structural material may deteriorate due to harsh environmental conditions. At the same time, the sediment will be accumulated at the reservoir bottom on the upstream side of the dam. The process of siltation depends on the reservoir topography and climatic variability, i.e., increased flood frequency and river inflow. The decision of retrofitting or strengthening the aged dam necessitates accurate analysis of the same in the presence of accumulated sediment. In this paper, an approach to include the time-dependent degradation of concrete owing to environmental factors and mechanical loading in terms of isotropic degradation index is presented. The absorption of pressure waves at the bottom of the reservoir due to the presence of sediments has been incorporated in the hydrodynamic pressure equation. The response of an aged concrete dam in the presence of sediment layers under seismic excitation is studied. The outcomes show the efficiency of the proposed algorithm. DOI: 10.1061/(ASCE)0733-9399(2007)133:4(400) CE Database subject headings: Dams, concrete; Finite element method; Reservoirs; Degradation; Absorption; Sediment.

This article deals with the seismic performance evaluation of concrete gravity dams considering fluid–structure–soil interaction in a finite-element framework. Two-dimensional finite-element formulation and analysis of dam–reservoir–foundation system was carried out in MATLAB code. A displacement-based Lagrangian technique was adopted for the dam and foundation domain, and the reservoir domain was modeled using the pressure-based Eulerian technique. The fluid–structure–soil interaction problem was solved using a direct coupling methodology. The coupled system consisted of three domains: dam, reservoir, and foundation. Free vibration analysis was performed to observe the effect of the interaction with the reservoir and foundation on the natural vibration modes of the dam. Dynamic response quantities of the dam, such as crest displacement and principal stresses at heel and neck were obtained considering interaction with and without the reservoir and foundation. The alteration in the responses of the reservoir and foundation based on the interaction with other domains was also examined. Emphasis was placed on the variation of the dynamic behavior of the dam, reservoir, and foundation when considered in a coupled manner. Finally, the seismic performance of concrete gravity dams was evaluated following a rational methodology based on the outcome of linear time history analysis. This study considered all the necessary modeling and analysis aspects to represent the actual physical scenario of the dynamic behavior of concrete gravity dams, and it provides a descriptive presentation of a simple and efficient approach for seismic safety assessment. [ABSTRACT FROM AUTHOR]