Shiraz University
Iranian Journal of Science and Technology Transactions of Civil Engineering
2228-6160
28
5
2013
03
02
Free vibrations of flexibly connected elastically supported stiffened coupled shear walls with stepwise changes in width
605
614
EN
10.22099/ijstc.2013.1112
In this study, a free vibration analysis of flexibly connected, elastically supported, stiffened coupled shear walls is carried out by a simplifying method widely used in the past for the static analysis of similar structures [1]. This method, called the continuous connection technique (CCT), comprises an efficient tool for the predesign computations related to the treatment of high-rise buildings. While the discrete structure is formulated as a continuous medium, the continuously distributed mass of the structure is discretized to a system of lumped masses for finding the corresponding flexibility matrix. After obtaining the standard frequency equation of the discrete system, the circular frequencies are determined in a straightforward manner and used to find the modes of vibration. Some comparisons are made between the results of the present method and those of a previous one, resulting in a perfect match of the two
Stiffened coupled shear walls,continuous connection technique,free vibration
http://ijstc.shirazu.ac.ir/article_1112.html
http://ijstc.shirazu.ac.ir/article_1112_d41d8cd98f00b204e9800998ecf8427e.pdf
Shiraz University
Iranian Journal of Science and Technology Transactions of Civil Engineering
2228-6160
28
5
2013
03
02
Non-linear elastic stability of rectangular frames under various loading
615
618
EN
10.22099/ijstc.2013.1113
The post-buckling behavior of rectangular frames in an elastic domain is studied in depth. In analysis, unsymmetrical geometry, sway possibility and support conditions are considered in order to find their influences on load-deflection paths and non-linear deformations. The static perturbation technique is used for analysis and discussion. The first, a second order perturbation problem as an accurate measurement for the frame, is solved and the solutions compared with previously published papers. The results reveal that symmetric frames with a sway movement, due to lack of an axial force in the beam in the first order perturbation analysis, have a symmetric bifurcation point. However, the post-buckling behavior of un-symmetric frames with or without sway is bifurcated in an asymmetric manner
Non-linear,post-buckling,Stability,frames,perturbation
http://ijstc.shirazu.ac.ir/article_1113.html
http://ijstc.shirazu.ac.ir/article_1113_d41d8cd98f00b204e9800998ecf8427e.pdf
Shiraz University
Iranian Journal of Science and Technology Transactions of Civil Engineering
2228-6160
28
5
2013
03
02
Strength and deformation properties of a schist rock in Isfahan
619
622
EN
10.22099/ijstc.2013.1114
In most parts of the city of Isfahan, at depths of 5 to 20 meters from the ground surface, schist is the predominant rock. This schist is a layered rock with variable thickness of 3 cm or more. Triaxial tests were conducted on the specimens with various anisotropic angles under confining pressures of 0, 7 and 15 MPa, and axial stress-axial strain were measured and plotted for various conditions.
<span style="font-size: x-small;">The results obtained reveal the effects of schistosity on the strength and deformability of the rock very clearly. The modulus of deformation of this rock varies with the anisotropic angle. For zero orientation, the modulus of deformation increases to a maximum. The results show that the friction angle and cohesion are affected by the anisotropic orientation, which is more important for the cohesion than the friction angles. It is not possible to apply failure criteria such as Mohr–Coulomb and Hoek–Brown for this rock without consideration of anisotropy orientation. </span>
Schist rock,Anisotropy,triaxial test
http://ijstc.shirazu.ac.ir/article_1114.html
http://ijstc.shirazu.ac.ir/article_1114_d41d8cd98f00b204e9800998ecf8427e.pdf
Shiraz University
Iranian Journal of Science and Technology Transactions of Civil Engineering
2228-6160
28
5
2013
03
02
An empirical model for prediction of conveyance efficiency for small earth canals
623
628
EN
10.22099/ijstc.2013.1115
Most of the water loss in distribution and conveyance earth canals occurs through seepage. This loss should be considered in irrigation network design through conveyance efficiency (e<sub>c</sub>). It is a common practice for the value of e<sub>c</sub> to be measured in existing irrigation systems under different soil types, vegetation covers and canal sizes. However, it is a costly and time consuming practice, therefore, empirical models to indicate the relationship between e<sub>c</sub> and soil texture, canal capacity and vegetation cover in earth canals may be effective in the estimation of e<sub>c</sub> at different conditions. This research was conducted to measure the conveyance efficiency in earth canals that are well above groundwater level with different soil textures and water weed densities in the northern and north-western areas of Isfahan province, I.R. of Iran. Conveyance efficiency of a km reach in distributary earth canals with a sandy loam soil was 67.3%, and for a clay loam soil in tributary earth canals 95.8%. The vegetation cover in the earth canal did not affect the e<sub>c</sub> value significantly. Therefore, it is concluded that traditional earth canals with medium to heavy soils in the study area have high e<sub>c</sub> and the lining may not be economically justified. Furthermore, for earth canals well above the groundwater level a multiple regression model was presented to estimate the e<sub>c</sub> value based on flow rates smaller than 404 <em>l</em> s<sup>-1</sup> in distributary and tributary canals and sand content in soil
Modelling,conveyance efficiency,small earth canal
http://ijstc.shirazu.ac.ir/article_1115.html
http://ijstc.shirazu.ac.ir/article_1115_d41d8cd98f00b204e9800998ecf8427e.pdf