Dear members, i need these papers:
Full-scale damping measurements of structures in Australia
Abstract:
Full-scale damping measurements were performed upon three classes of civil engineering structures including free-standing lattice towers, reinforced concrete buildings and pedestrian footbridges. Most of these structures were subjected to forced vibration tests to obtain structural damping estimates. Autocorrelation and random decrement procedures were used to extract total damping from load-induced resonant response signals. Both these procedures were further scrutinised in light of the measured results. A simplified analytical expression for aerodynamic damping was derived. Some damping predictors were proposed based upon the findings of this paper.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
http://forum.civilea.com/thread-27464.html
***************************************
Along-wind response of lattice towers—II. Aerodynamic damping and deflections
Abstract:
The analysis of the along-wind dynamic response of freestanding lattice towers in Part I, is continued in this paper. The expression for the ratio of the aerodynamic damping coefficient to the critical value is derived. The mean, background and resonant components of the deflection at the top of a tower, required for serviceability design considerations, are also derived. The results are all given in a ‘closed form’. Finally, the sensitivity of the gust response factors to calculation height, taper ratio and mean velocity, is investigated for a representative tower.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
http://forum.civilea.com/thread-27464.html
***************************************
Along-wind response of lattice towers: part I - derivation of expressions for gust response factors
Abstract:
The along-wind dynamic response of free-standing lattice towers is considered. Expressions are derived for the gust response factors applicable to the shearing force and bending moment at an arbitrary height on a linearly tapered tower. These expressions are similar in form to those previously used for the gust response factor, but include extra factors which incorporate the effects of various parameters associated with the wind and the structure, such as mode shape, mean velocity profile, taper, type of load effect, and its elevation on the tower.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
http://forum.civilea.com/thread-27464.html
***************************************
Guyed masts under wind load
Abstract:
The essential requirement for a safe and economic design of guyed masts is an exact knowledge about wind loading and the corresponding response of the structure. In thisresearch project windprofiles and statistical parameters of the turbulence structure are determined by measuring the wind speeds on 17 levels with relatively small vertical distances (18m) up to the height of 341m. The dynamic response of the mast is determined by measuring the strains of the corner legs and the rope forces as well as the accelerations of the mast shaft. Based on the experimental results a system identification is performed, taking account of the nonlinearities of the ropes. Calculated results are compared with measured ones.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
http://forum.civilea.com/thread-27464.html
***************************************
Dynamic gust response factors for guyed towers
Abstract:
The dynamic component of guyed tower response is generally larger than the mean component and has significantly different characteristics. Predictions of peak response based on the static behaviour under steady winds can give misleading and often unconservative results. A simplified method for estimating dynamic response is presented that uses a series of static load patterns to approximate the effects of gusting winds. The response to these patch loads is modified by factors that depend on the physical properties of the tower and the characteristics of the wind. Comparisons are made between the patch load method, the gust factor method, and the more rigorous statistical method.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
http://forum.civilea.com/thread-27464.html
***************************************
Geometric non-linear analysis of three-dimensional guyed towers
Abstract:
Three-dimensional geometric non-linear analysis of guyed towers using linear isoparametric formulation within an updated Lagrangian coordinate framework is presented. The complex non-linear behaviour of the guy cables is simplified by the equivalent modulus approach. Shear locking of the two-noded beam element is corrected by reduced order of integration and altering the elastic coefficient for the transverse shear. The formulation is general enough to include transverse shear effects, eccentricity of the centroidal axes from the beam shear centre and the product of inertia of the beam cross-section. A typical guyed tower example is solved and results are compared with the published work.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
http://forum.civilea.com/thread-27464.html
***************************************
Nonlinear seismic response of antenna-supporting structures
Abstract:
In the event of a severe seismic excitation, preservation of essential infrastructures, such as telecommunication facilities, is of high priority. The objective of this paper is to investigate the geometrically nonlinear response of antenna-supporting guyed towers under earthquake loading. Two guyed towers are analysed: a 350 ft (107 m) tower with six stay levels and an 80 ft (24m) mast with only two stay levels. Two horizontal accelerograms are used, El Centro and Parkfield, with each record being scaled to match the elastic design spectra of the 1990 National Building Code of Canada. Elements of response analysed are: guy tensions, horizontal shears, and displacements and rotations at the tip of the mast. Results indicate that although the absolute values of the dynamic amplifications are well below the limit strength and serviceability criteria for such towers, dynamic interactions between the guywires and the mast are important, especially in the vertical direction. Multiple support excitation of the tallest tower also causes additional dynamic effects that are not present when only synchronous ground motion is studied.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
http://forum.civilea.com/thread-27464.html
***************************************
Nonlinear dynamic response of a guyed tower to a sudden guy rupture
Abstract:
The geometrically nonlinear dynamic response of a three-dimensional model of a guyed tower, when a selected guy suddenly ruptures, sending an impulsive shock to the entire structure is studied. The sudden rupture of a guy is simulated by the instantaneous removal of its end tension, applied as an external force at its mast attachment point. A 500 ft tall tower with three stay levels was analysed. The analysis was performed for a nominal wind speed acting in the plane of the ruptured guy, assumed to be a windward one. The mast was modelled by a three-dimensional space truss and the guys by three-dimensional elastic catenaries.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
http://forum.civilea.com/thread-27464.html
***************************************
Analysis of cable structures
Abstract
A numerical procedure has been developed to analyze complex 3-dimensional assemblies of substructures and cables. The procedure is applicable to guyed towers, flexible transmission lines, cable roofs or mooring networks. The computer program, which has been developed to analyze these composite structures, accepts arbitrary loads on the substructures but restricts the loads on the cable elements to gravity, thermal, or fluid drag effects.
The algorithm is built around an efficient cable element subprogram. From given loads and given positions of the ends of a cable, the subprogram determines the complete geometry of the cable, its end forces, and its tangent stiffness matrix. The cable elements are connected together or to substructures nodes.
The equilibrium configuration of the assembly is approached by successive iterations which decrease the imbalance of forces which still exist at each node at the end of the previous iteration. Special numerical schemes, which insure rapid convergence of the analysis, are presented.
The computer algorithm is discussed in detail, and the simplicity and efficiency of the formulation is demonstrated by several examples. Very large displacements of the nodes and associated second order effects on the substructures do not present any difficulty as the imbalances and stiffnesses at each iteration are based on the geometry of the system at the end of the previous iteration.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
http://forum.civilea.com/thread-27464.html
***************************************
Interactive graphics for guyed tower analysis
Abstract
The interactive graphic features of a special purpose software for the nonlinear analysis of guyed towers are described.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
http://forum.civilea.com/thread-27464.html
***************************************
Dynamic gust response factors for guyed towers
Abstract
The dynamic component of guyed tower response is generally larger than the mean component and has significantly different characteristics. Predictions of peak response based on the static behaviour under steady winds can give misleading and often unconservative results. A simplified method for estimating dynamic response is presented that uses a series of static load patterns to approximate the effects of gusting winds. The response to these patch loads is modified by factors that depend on the physical properties of the tower and the characteristics of the wind. Comparisons are made between the patch load method, the gust factor method, and the more rigorous statistical method.
Code:
***************************************
Content of this section is hidden, You must be registered and activate your account to see this content. See this link to read how you can remove this limitation:
http://forum.civilea.com/thread-27464.html
***************************************
regards,
apocalipse