Volume 1 Issue 4
Authors: Aly El-Kafrawy
Abstract: In the present paper, a non-dimensional mathematical model for high tower buildings and its foundation under randomly fluctuating wind loads and earthquake ground motions excitations is developed as a nonlinear model to study the system more extensively. The main equations of the system could be derived using two different derivation methods, linearized in minimal symbolic forms; which facilitate a subsequent numerical simulation in order to investigate the vibration characteristics of the whole system. The analysis enables designers to have more insight into the characteristics of high tower buildings of similar configuration but with different geometry and material. The complexity of wind loading with its variations in space and time has been considered. A comprehensive mathematical model of six degrees of freedom is presented and solved for free and forced vibrations.
Keywords: Tall Building Vibrations; Modal Analysis; Foundation Vibrations; Power Spectral Density; Random Wind Excitation; Earthquake Ground Motions
Authors: Nikolay N. Karabutov
Abstract: Methods of structural identification of processes in systems of civil engineering with the nonlinearities which are belonging to the class of the hysteresis are considered. Methods are based on the multiple-informational approach which is based on the analysis of static structures, reflecting a condition of nonlinear system of identification. The criterion is introduced, allowing making the solution on level of linearity (nonlinearity) of processes in parametrical space on set of secants. Algorithms of definition of structural parameters hysteresis nonlinearities on the basis of the analysis of properties of special static structures are offered. The mode of construction of functions of saturation and hysteresis on a class of random inputs is developed.
Keywords: Structure; Identification; Saturation; Hysteresis; Model; Secant
Authors: Castorina Silva Vieira; Maria Lurdes Lopes; Laura Caldeira
Abstract: The paper presents a numerical study carried out to analyse the influence of the facing panel properties on the seismic response of a 6 m high geosynthetic reinforced soil retaining wall with continuous facing panel. The effect of the restraining condition at the toe of the facing panel and its bending stiffness are analysed. The lateral displacements and the reinforcement tensile loads at the end of construction and after a potential earthquake are analysed and compared. The numerical analyses showed that the facing panel bending stiffness has a significant influence on the pattern of lateral displacements and on reinforcement tensile loads.
Keywords: Geosynthetics; Reinforced Soil Retaining Walls; Facing Panel Stiffness; Numerical Modelling; Seismic Loading
Authors: Keenam Song
Abstract: A PHE (Process Heat Exchanger) is a key component in transferring the high temperature heat generated from a VHTR (Very High Temperature Reactor) to the chemical reaction for the massive production of hydrogen. A performance test on a small-scale PHE prototype made of Hastelloy-X is currently under way in a small-scale nitrogen gas loop at the Korea Atomic Energy Research Institute. Previous research on the high-temperature structural analysis of the small-scale PHE prototype has been performed using the parent material properties over the whole region. In this study, high-temperature structural analysis considering the mechanical properties in the weld-affected zone was performed.
Keywords: Process Heat Exchanger; High-Temperature Structural Analysis; Heat Affected Aone; Weld
Authors: Spyridon S. Kouris
Abstract: Strong earthquakes caused damages or collapses of vulnerable masonry structures. Over the last few decades, a great number of historical masonry bell towers which were erected in areas of relatively high seismic activity, have suffered from damages and cracking by earthquakes. In addition to these damages other causes, as thermal and hydroscopic strain and cyclic stress caused by wind action can act in combination with the long term phenomena and contribute to worsen the damages. Consequently, some of the most known bell towers have collapsed today or have been reconstructed. So, the medieval tower of Pavia (Italy) collapsed on March 17th, 1989, the bell tower of Cathedral of Monza (Italy) collapsed in May, 1993, the Cathedral of Noto (Sicily-Italy) collapsed in March 1999, the bell tower of St. Mark in Venice collapsed in 1902 and it was rebuilt later and many other cases. The few survived till today masonry “slender” bell towers are under considerable damages (such as the bell towers on Corfu island in Greece) and many of them are masterpieces of architecture in the past centuries. The aim of this paper is to describe the behavior of these bell towers under dynamic loading and to research how the geometry of these structures and the ground soil has affected their response to earthquakes. The finite element program SAP 2000 has been used for the study of the dynamic analysis of bell towers.
Keywords: Frequencies; Dynamic Analysis; Masonry Bell-tower
Authors: Essam Zaneldin; Bilal El-Ariss
Abstract: Fiberreinforced polymer (FRP) matrix composites developed for other industries are relatively new in civil construction, both for the rehabilitation of existing structures and for the construction of new structures. In the last two decades a number of civil infrastructure applications have been constructed or rehabilitated with FRP components. Cost-effectiveness, durability, optimized structural panels, and satisfactory repair and retrofit methods have been achieved with the use of FRP in construction applications. The objective of this paper is to present the status of FRP composites asstructural materials in building and construction applications. Parameters that affect their mechanical properties are addressed. Development of codes and standards for FRP composites will widely contribute to their acceptance and adoption in building and construction industries.
Keywords: CompositeMaterials; FRP;Retrofit; Rehabilitatio; Structures; Bridges