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Turbo-generator machines while operation generate harmonic load on the foundation which may create heavy vibration in case it’s not considered in the foundation design. The present work studies the effect of raft, pile with raft and barrettes with raft subjected to harmonic load on the turbo-generator foundation in medium dense and partially saturated sand. Detailed computational analysis was carried out with the help of SAP; 2000 software; the numerical model was analysed and compared with the experimental results. Both experimental and numerical results reveal that the displacement at top deck is lower for barrettes compared to raft and pile structures, which results in least vibration at top deck for barrette-supported turbo-generator foundations. There is also decrease in spectra acceleration, stress, base shear and increase in natural frequency in barrette-supported foundations compared with raft- and pile-supported foundations. Hence, barrettes with raft are recommended under dynamic loading in poor soil conditions because it transfers the dynamic load through columns to barrettes thus increasing the stability of the turbo-generator foundation. [ABSTRACT FROM PUBLISHER]

The main objective of this study is to develop a new measurement technique without touching the measured object. Digital Image Correlation (DIC) is an advanced measurement technique used to measure the displacement of particles with very high accuracy. This powerful innovative technique is used to correlate two image segments to determine the similarity between them. For this study, three geometrically similar beam specimens of different sizes were cast and tested under three-point bending in a closed loop servo-controlled machine with crack mouth opening displacement control with a rate of opening of 0.0005 mm/sec. Digital images were captured before loading (unreformed state) and at different instances of loading and analyzed using correlation techniques to compute surface displacement, crack opening and sliding displacement, loadpoint displacement, crack length and crack tip location. It was seen that crack mouth opening displacement and vertical load-point displacement computed using DIC analysis match well with those experimentally measured. [ABSTRACT FROM AUTHOR]

Granular piles are frequently used as a method of improving soft grounds as they provide increased bearing capacity and reduce foundation settlements. However, in very soft clayey soils, they may not derive their load-carrying capacity by low confining pressure provided by the surrounding soil. In such circumstances, granular piles may be reinforced with suitable geosynthetic to increase its load-carrying capacity and to reduce excessive bulging. In this study, the performance of small group of geosynthetic-reinforced granular piles (GRGPs) is examined in terms of load-carrying capacity, settlement, and modulus by laboratory model tests. The parameters investigated include modulus of reinforcement material, area replacement ratio (ARR) based on the column diameter and reinforcement length. The results indicated that increasing the modulus of the reinforcement and the ARR based on the column diameter enhances the overall performance of the GRGP group. It was also observed that reinforcement on top portion of the granular pile is sufficient to substantially increase the load-carrying capacity of granular pile group. [ABSTRACT FROM AUTHOR]

Foundation plays a significant role in safe and efficient turbo machinery operation. Turbo machineries generate harmonic load on the foundation due to their high speed rotating motion which causes vibration in the machinery, foundation and soil beneath the foundation. The problems caused by vibration get multiplied if the soil is poor. An improperly designed machine foundation increases the vibration and reduces machinery health leading to frequent maintenance. Hence it is very important to study the soil structure interaction and effect of machine vibration on the foundation during turbo machinery operation in the design stage itself. The present work studies the effect of harmonic load due to machine operation along with earthquake loading on the frame foundation for poor soil conditions. Various alternative foundations like rafts, barrette, batter pile and combinations of barrettes with batter pile are analyzed to study the improvements in the vibration patterns. Detailed computational analysis was carried out in SAP 2000 software; the numerical model was analyzed and compared with the shaking table experiment results. The numerical results are found to be closely matching with the experimental data which confirms the accuracy of the numerical model predictions. Both shake table and SAP 2000 results reveal that combination of barrette and batter piles with raft are best suitable for poor soil conditions because it reduces the displacement at top deck, bending moment and horizontal displacement of pile and thereby making the foundation more stable under seismic loading. [ABSTRACT FROM AUTHOR]

Accomplishing maximum spans by creating new bridge systems has always been an interesting logical challenge. The concepts of modified cable-supported bridges have been proposed in the past that promise to surpass the more traditional cable-supported bridges in terms of maximum span length. The innovation in structural form, material technology and methods of analysis serve economy and better performance for longer span bridge structural system. The construction of long-span bridge is possible using high strength materials, innovative forms of structural system and novel method of analysis and design. The cable-stayed bridge and suspension bridge are structural systems used to achieve longer span bridges. The cable-stayed bridge has better structural stiffness and the suspension bridge has the ability to provide longer central span. To achieve a very long-span bridge with better structural behavior, a combination of the above two structural systems serves the purpose. The innovative form of hybrid cable-stayed suspension bridge with 1400 m main span and 700 m central suspension portion is considered for the analysis. The geometrical parameter like length of side span also plays an important role in the behavior of bridges. In this paper, bridge behavior is presented for variable length of side span. Nonlinear static analysis and modal analysis are carried out using SAP2000 software. The effects of side span length on the static performance of bridge are presented in the form of axial forces in deck and main cables. The dynamic behavior of the bridge is presented in the form of time period of bridge in lateral and vertical directions. [ABSTRACT FROM AUTHOR]

With the development of the enhanced materials and techniques for analysis of bridge, long span cable-supported bridges are introduced. Cable-supported bridges comprise both suspension and cable-stayed high strength bridge systems. Both these forms of cable-supported bridge are flexible structures in behavior. These flexible systems are susceptible to the dynamic effects of wind and earthquake loads. With the increasing span of the bridge, the flexibility of the bridge is escalating. In this paper, an attempt is made to enhance the rigidity of long span bridge . For enhancing the rigidity of the bridge in lateral and vertical directions, a different configuration of the cable-stays of long span cable-stayed bridge is considered. To understand the response of the long span cable-stayed bridge, the modal time history analysis is carried out in SAP2000 software. The parameter considered to analyze the cable-stayed bridge is dissimilar to cable-stays configuration. The behavioral response of the bridge is presented in the form of a time period in lateral and vertical direction for structural members of the bridge. [ABSTRACT FROM AUTHOR]

Stone column is often employed for strengthening of an embankment seated on deep sot clay. But in very sot clay having undrained shear strength less than or equal to 15 kPa, stone column may not derive adequate load carrying capacity and undergo large lateral deformation due to inadequate lateral confinement. In such circumstances, reinforcement to individual stone column by geosynthetics enhances load carrying capacity and reduces lateral deformation. This paper addresses parametric study on behaviour of embankment resting on Geosynthetic Reinforced Stone Column (GRSC) considering parameters such as stone column spacing to diameter ratio, deformation modulus of stone column material, geosynthetic stiffness, thickness of sot clay, and height of embankment by 3D numerical analysis. Finally, equation for Settlement Improvement Factor (SIF), defined as ratio between settlement of embankment without treatment and with geosynthetic reinforced stone column, is proposed that correlates with the major influence parameters such as stone column spacing to diameter ratio, deformation modulus of sot clay, and geosynthetic stiffness. [ABSTRACT FROM AUTHOR]