Shed calculations
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Shed calculations

Inclined steel frames, which are also called shed calculations, are used to cover large openings in buildings such as factories, warehouses, airplane hangars, sports halls, etc. This type of covering has advantages over other types of trusses, the most important of which are: saving materials and construction and installation time, a more beautiful view and more use of the space under the roof, it shows different types of inclined frames.

Types of shed frames

Figure 1 - Types of shed frames

The general principles that are taken into consideration in the Sule calculation book are as follows:

General calculations of the shed
including the general characteristics of the structure such as the number of openings, the type of structural system

The side load resistant system in sheds is usually as follows.

In the longitudinal direction, it is a simple articulated frame with a cross-type converging bracing system, and in the transverse direction, it is a medium bending frame.

The structural system of the shed

Figure 2 - Structural system of the shed

Specifications of consumables

Regulations used in analysis and design

The loading of the structure is done in accordance with the sixth topic of the 92nd edition and the 2800 standard of the fourth edition.

The metal frame and all the connections of the structure are designed manually and based on the requirements of the seismic design of the 10th issue of the 92 edition.

The lateral and vertical rise of the structure for different loads has been controlled according to the EuroCode 3 standard.

The maximum length of the structure has been controlled according to AISC360 due to the necessity of installing the expansion joint.

ACI318 standard as well as Iran's concrete regulation, topic 9 are used for foundation design.

Software used in analysis and design and drawing

Shed design with SAP2000 and SAFE and shop in Tekla Structures and drawing maps in two modes as BIM and Autocad

Structural loading in shed calculations
Dead load, which includes the load of structural members, load of purlins and roof covering.

Snow load considering the effect of slope and asymmetric distribution of snow

The snow load on the ground, Pg, is the weight of the snow layer on the horizontal surface of the earth, which according to the statistics in the region, the probability of exceeding it is 2% per year (return period of 02 years) is the snow load on the ground in different regions of the country.

Sole snow load


Wind load, wind reciprocation effect and pressure and suction on the roof and every extension

Buildings and structures and all their components must be designed and built for the effect caused by wind, based on the rules of this chapter. This effect should be calculated according to the average wind speed in the area, the height and geometrical shape of the buildings, and the amount of covering and blocking that the adjacent obstacles create for them in front of the wind.

earthquake load

We carry out the earthquake loading according to the 2800 regulation for the structure.

Thermal loads, contraction and expansion

We carry out the thermal loading of the structure based on the President's Strategic Management Publication 325.

Crane load in industrial sheds

The crane's live load depends on its operating load. In bridge and single-rail cranes, the design loads of the beams below the series along with their connections and seats must include the maximum load of the crane bridge wheel, vertical impact, and lateral and longitudinal loads caused by the movement of the crane.

The heavy load of the shed

Figure 5 - Heavy load of the shed

Design for stability in shed calculations
The 10th issue of the 92 edition has proposed three methods to determine the required axial and bending capacity of the members.

Direct analysis method

Effective length factor method

First order analysis method

Ensuring the stability of the entire structure and all its components is one of the requirements of analysis and design. According to the requirements of this section, the stability of the entire structure and all its components is provided if the works mentioned below are effectively included in their analysis and design.

Axial, bending and shear deformations of structural members and deformations of other components (such as connections) that are effective in moving the structure.
The works of the second order include the works of 𝑃−𝛿 and 𝑃−ფ))
Geometric defects (including crookedness and unevenness)
Reducing the stiffness of members due to inelastic behavior mainly due to residual stresses
Uncertainty in estimating hardness and strength
Lateral displacement control

The European regulation stipulates that the vertical movement of the crown of the shed under gravity loads and the lateral movement of the shoulder under wind load should be controlled in the service mode.

Rollover control

If we consider the effective weight of the overturning anchor only due to the dead load and ignore the weight of the side walls and foundation, we control the overturning for two loads of wind and earthquake.

Shed design and calculations
Design of rafter and column

Column and behavior of the shed
Figure 6 - Column and structure of the shed

Stress ratio in critical frame members

Shed analysis

Figure 7 - Analysis of the shed

Design of lateral and roof restraints

Shed bracing

Figure 8 - bracing of the shed

Purlin or lape design

In general, logs should have the ability to withstand bending caused by dead loads, snow and wind loads. The main regulation for the design of these sections is the AISI96 regulation, the translation of which was recently published by the strategic management of the president under the title of publication 219.

Perlin or Lape Sule
Figure 9 - Perlin or Lape Sule

Bra design

In order to prevent lateral buckling of the main girder of the frame in the parts where the lower wing is under pressure (negative anchor areas), the compression wing is restrained by means of a lateral restraint called a bra to the joists on both sides of the frame.

Shed BRA design
Figure 10 - design of the bra of Sule

Sagrod design

Strat design

Strat Sule

Figure 11 - Strat Sule

Design of lateral restraints and their connections

Shed restraints

Figure 12 - shed restraints

Column page design

Usually, the face of the columns is designed assuming the joint behavior of the column foot in the shed

.

The floor of the pillar of the shed
Figure 13 - The floor of the shed column

Foundation design

We consider the range of load transfer from the column to the foundation to be approximately equal to the average dimension of the column and column plane. We connect the individual foundations with coils. These coils do not have a bending function and are used only to integrate the piles.

Pi Sule

Figure 14 - Foundation of the shed

Wall post or wind column design

The way of connection is that a sheet is welded under the lower wing of the rafter and the post wall is connected to this sheet by means of two screws. To connect the wall post to the rafter, we use a screw connection with a long bean hole.

Sole wind column

Figure 15 - Sole wind column

Crane beam design

The design of the crane beam is done through its loads in the most critical state.

Crane carrier beam

Figure 16 - Crane carrier beam

Crane bracket design

We assume that the carriage is placed near the bracket in such a way that the point of origin of the forces from the guide wheels is located exactly in the middle of the bracket. Therefore, the bracket connection should be equal to 2Q for the shear force.

Shed crane bracket
Figure 17 - Shed crane bracket

Bolt harness design

The restraining length of hook bolts will be equal according to ACI.

The desire to restrain the foundation of the shed
Fig. 18. The support shaft of the shed foundation