Termining the Dynamic Properties of Castellated Beams Using the White-Noise
mohammadali
lotfollahi
author
text
article
2004
per
In investigation of dynamic specifications of castellated beams, it is necessary to be studied the excitation intensity of dynamic mode shapes for different loading conditions. It is evident that for a specific loading, not all modes of a structure are excited and the structural response depends on the applied loading specifications. In this paper using the finite element method (based on ANSYS software), a dynamic load with properties of white noise in a proper frequency range is applied on the both cantilever catellated and plain webbed beams. The dynamic specifications and different excited modes of them are taken into investigation. It could be seen that the loading conditions are very important in order to excite and define the dynamic specifications of these beams. In a uniformly loaded cantilever beam with the white-noise properties, merely some of the vibration modes, that is, the flexural modes are excited and the effects of some of the other modes such as torsional modes are eliminated. Therefore, in order to excite all of the vibration modes a loading with proper frequency band should be applied. Also it should be mentioned that the current method indicates that castellated beams are weak in comparison with plain webbed beams subjected to dynamic gravity loads which cause bending moments and excite the flexural modes.
آنالیز سازه - زلزله
دانشگاه آزاد اسلامی واحد مراغه
2345-6310
1
v.
1
no.
2004
2
9
http://civil-strj.iau-maragheh.ac.ir/article_518727_80366554f18c428a0e983fdc9957bd39.pdf
Experimental Study of Volume Change and Swelling Pressure Of Compacting of Clay Soil
imam
ashayeri
author
shahab
yasrebi
author
text
article
2004
per
Expansive behavior is usually observed in Soils, Which Contain fractions of clay minerals in their composition. Water absorption of clay particles and change of natural water content of soil up to plastic limit and down to shrinkage limit will cause significant volume change in expansive soils and will result in severe damages to the structures, buildings and foundations. Swelling potential is directly related to clay minerals activity and soil plasticity. Besides all the parameters expressing composition of a soil environmental conditions provide conditions to free the swelling potential. In the present study, in order to observe effects of soil mineralogy, plasticity and compaction indices such as water content and dry unit weight swelling behavior of five clay soils with plasticity index of 10 to 60 has been investigated. Free swelling and constsnt volume swelling pressure tests have been done on compacted samples. Results of experiments indicate the swelling potential increases by increasing plasticity Index, and clay size fraction in soil composition.
آنالیز سازه - زلزله
دانشگاه آزاد اسلامی واحد مراغه
2345-6310
1
v.
1
no.
2004
10
15
http://civil-strj.iau-maragheh.ac.ir/article_518728_c9850f50b1be4bb3859ce90143446a3b.pdf
Using Mushroom Shaped Basements under Buildings Isolator in Order To Reduce the Earthquake Effect on Structures
agi
bairami
author
Majed
bargiyan
author
text
article
2004
per
A new base isolation method for reducing the destructive effect of earthquake is proposed in this method mushroom shaped basements are used under structures as base isolation. These basements have spherical surface and are located on foundations. Basements have pinned arms that are connected. When the length of the arm is less then the radius of spherical surface, the action of them is similar to a spring. In other words, when a displacement in a structure happens. A returning force is supplied to the structure and the stability of the structure is guaranteed. The specification of these springs is so that their stiffness can easily be set. As the stiffness is settable therefore the stiffness can be set in a way that firstly, the force applied to the structure will be acceptable, the maximum displacement will not exceed allowable limit. In this research the basements together with the structure were modeled as a one-degree freedom system of mass, spring and damper.
آنالیز سازه - زلزله
دانشگاه آزاد اسلامی واحد مراغه
2345-6310
1
v.
1
no.
2004
16
22
http://civil-strj.iau-maragheh.ac.ir/article_518729_94ad7db6920ed37b2350ea352f4b7c3f.pdf
Experimental Study of Buckling and Postbucking Behavior of Cylindrical Shells
Hossein
showkati
author
text
article
2004
per
The buckling and postbuckling response of laterally pressurized cylindrical
Shells was investigated experimentally, with special attention given to the influence of elastic boundry condition. In this program two speciments were fabricated from mild steel sheets of 1 meter length, 1 meter diameter and 0.55 mm thickness, they were tested under the action of inertial vacuum. Initial geometric imperfections were measured. Their behavior was characterized by prebuckling, initial buckling overall buckling, postbuckling and final collapse by a local torisional failure. The final deformations were measured.
آنالیز سازه - زلزله
دانشگاه آزاد اسلامی واحد مراغه
2345-6310
1
v.
1
no.
2004
24
30
http://civil-strj.iau-maragheh.ac.ir/article_518730_ad1dcfc3fb4b42ba1129e8fb371381d8.pdf
Estimating the Properties of Fundamental High Strength Concrete with Statistical Methods and A.N.Ns and their Comparison
mehdi
rezai
author
Mohammadreza
henaglo
author
hassan
afshin
author
text
article
2004
per
آنالیز سازه - زلزله
دانشگاه آزاد اسلامی واحد مراغه
2345-6310
1
v.
1
no.
2004
32
37
http://civil-strj.iau-maragheh.ac.ir/article_518731_a71154a4eba6f476d818f55631e36c50.pdf
Using Finite Element Method in Investigation Influence of an Opening on Reinforced Concrete Slabs
mohammad
lotfollahi
author
Hamidreza
golgon
author
text
article
2004
per
آنالیز سازه - زلزله
دانشگاه آزاد اسلامی واحد مراغه
2345-6310
1
v.
1
no.
2004
38
43
http://civil-strj.iau-maragheh.ac.ir/article_518732_127d9019c5a94aff05bb98116f4a1237.pdf