تجزیه و تحلیل مهار دکل مشبک فولادی تحت بار زیست محیطی

ساخته شده از آهن مشبک فولادی در میان تحمل بار سازه کارآمد ترین در زمینه ساخت و ساز بلند رتبه. تجزیه و تحلیل غیر خطی از یک دکل مشبک فولادی مهار شده با استفاده از SAP انجام شده است 2000 برنامه محدود عنصر برای مقادیر ضخامت یخ های مختلف در 1500 متر از ارتفاع. پس از تعریف مدل هندسی و متقابل- خواص بخش, ترکیبات بار های مختلف مورد تجزیه و تحلیل. سرانجام, سرعت باد- رابطه ضخامت یخ به دست آمده است, و حداکثر سرعت وزش باد است که ساختار می تواند تحمل برای متفاوت ضخامت یخ تعیین.

1. مقدمه

Lattice mast is a general name for different kinds of steel masts.A lattice mast or truss mast is a freestanding framework mast. These structures can be used as transmission masts especially for

voltages of more than 100 kilovolts, as radio masts (self-radiating masts or carriers for aerials), or as observation masts for safety purposes. Big and heavy frame sections are not required in these

masts. This is why they are lighter than other mast types, and the modules can easily be connected to one another.

Steel lattice masts have been used for many years in the countries where the ice and wind loads are considerable. This is due to increasing demands of modern industry with regard to communication and energy. There are different styles of masts on which small wind generators are mounted: freestanding, guyed lattice, and tilt-up. Freestanding masts are relatively heavy duty, and they stay upright without the help of guy cables. Guyed lattice masts use guy cables to anchor the mast and keep it upright using a relatively small quantity of concrete. Cables stretch from three points near the top of the mast to the ground at some distance from the base of the mast. These constructions are quite light compared to freestanding masts, and therefore constitute the least expensive means for supporting a wind turbine. با این حال, they require a larger area to accommodate the guy cables.

The technical efficiency and durability of steel lattice masts have increased in recent years. The behaviour of steel lattice masts has been investigated in literature. As the design procedure is significant in these masts, the structural analysis is related to the geometrical model and section properties. بدین ترتیب, the module production and assembly steps, and economic costs, are directly related to the design of masts. Steel lattice masts on land are vulnerable structures. They are mostly affected by environmental loading. Wind loads are the most effective design criteria for these structures. با این حال, the ice effect must also be taken into consideration, especially at high elevations. In cold regions, these two effects are combined. از این رو, the relationship between the wind and ice must be investigated by conducting proper finite-element analyses to avoid the collapse of such structures. In this paper, the non linear analysis of a guyed steel lattice mast 80 m in height is performed using the SAP 2000 program. While the model is constituted according to TS 648 load conditions are taken from TS 498. The altitude of the structure is taken to be 1500 متر, and the snow region IV is adopted, which is the most conservative option. در این روش, the analysis can also be used for other snow regions. The structure was first analysed without any ice effect. Afterwards, the ice thickness was gradually increased, and the relationship between the wind speed and ice thickness was determined.

2. Materialand method

Proper sections and angles of the steel lattice mast are first determined. Afterwards, the three dimensional finite element model is given in Figure 1. Top view of the model is presented

in Figure 2. Face sections of the model, showing the distances with angles, are shown in Figure 3 and Figure 4.

شکل 1. 3-D مدل

شکل 2. بالا چشم انداز

شکل 3. A و B صورت بخش

شکل 4. C صورت section

جدول 1. ماده properties

جدول 2. section properties

جدول 3 سرعت باد و بارهای با توجه به ارتفاع

A module 3015 mm in length is made of steel members. Columns are placed at an angle of 900 to the ground. Vertical steel members connect columns to one another, and are placed vertically with respect to the columns. Diagonal members are placed by definite angles to the columns, and they also connect the columns to one another. A column with diagonal and vertical members that constitute the module, are shown in Figure 5.

شکل 5. واحد اعضا

Guy members and modules are named according to the total height from the ground level. The guy and section numbers, with related heights, are presented in Figure 6.

جدول 4. خواص ارتفاع و برف

جدول 5. یخ properties

وجود دارد 26 ماژول ها در دکل شبکه. ستون, عمودی,و اعضای مورب در هر صورت از ماژول هستند شکل shownin 7. جهت باد مثبت و منفی موثر بر
ماژول نیز در شکل ارائه شده.

جدول 6 خواص بخش

Load combinations used in the analysis are given in Eqn (1) and Eqn (2) as follows. The combinations are constituted by Snow loads, ice loads according to ice thickness values,

and wind loads effecting different heights of the lattice mast with wind speeds are given in Table 7.

اثرات بار جانبی اعضای. بار برف توزیع شده است با در نظر گرفتن سطح بالای اعضای محاسبه.