BEAM – TO-COLUMN CONNECTION CALCULATIONS USING ROBOT SOFTWARE

A beam–to-column connection design and results of engineer calculations using Autodesk’s Robot Structural analysis are shown in the article. Two types of connections, bolted and welded, were calculated. The tensile resistance amounted to 912.74 kN, bending resistance to 100.87 kN·m and effective design capacity of the bolt amounted to 27.69 kN. Normal stress in the weld amounted to σ⊥max = τ⊥max = 72.72 MPa, in the vertical weld to σ⊥= τ⊥= 63.34 MPa and tangent stress amounted to τ|| = 4.37 MPa. The results allowed us to implement minor changes such as increasing the distance between the bolt and the edge and decreasing the size of the fillet welds. The design is fully compliant with the EN 1993-1-8 norm. Using Robot Structural Analysis substantially increased the pace of calculations giving precise and clear outcomes.


INTRODUCTION
Computer assistance in an engineer's work is currently getting more effective and precise.The automation of the design process makes the time of project completion shorter and increases competitiveness of a product [3].Autodesk's Robot Structural Analysis is one of the tools facilitating the work of designers and constructors [1,3].
Autodesk Robot Structural Analysis is an integrated graphic application used for modeling, analysis and dimensioning of various construction types.The program features construction design, carrying out static calculations of a construction, outcomes verification, standardized calculations of construction elements and gathering documentation for calculated and dimensioned constructions.The most relevant features of the Robot include: • a fully graphic definition of construction in the graphic editor (loading a DXF file containing construction geometry prepared with a different program is also possible).
• a possibility of a graphic representation of the designed construction as well as displaying various calculation outcomes (force, displacement, multiple windows work etc.) • calculation of the construction (dimensioning) while designing another construction (multithreading), • carrying out static and dynamic construction analyses, • assigning the rod type while creating the construction model, not in standard modules.• composing any type of print (calculation notes, screenshots, print composition, exporting objects to other programs) [1].

DESIGN OF CONSTRUCTIONAL CONNECTION
The main function of the connection is to distribute the internal forces between the elements.In a steel construction basic elements such as columns, beams, bracings and ties are used.Next, the components of the external building parti-tions-ceilings and partition walls -are attached to the main constructional elements.The most commonly used connection types in multi-storey buildings are [2,4,5]: • articulated nominal connections (beam-tobeam and beam-to-column), • moment connections (beam-to-column) in case of continuous frames, • bracings connections, • column bases.
A type of beam-to-column constructional connection was designed using Robot Structural Analysis software (Fig. 1).The column is an Hsection of an IPE 220 profile and the beam of an IPE 200 profile.St3S steel was used in both parts.

Fig. 1. Beam-to-column connection model
The type of connection, material and profiles geometry were chosen before the calculations.The parameters, e.g.forces and moments, can be set automatically with possible manual modifications in the edition mode.
For this particular connection bolted and welded connections were planned.There were five rows and three columns of 10.9 grade bolds.The sizes and loads in this particular project are presented in Figure 2.

ENGINEER CALCULATIONS OUTCOMES
The next step using Robot Structural Analysis was to carry out engineer calculations and control calculations to verify the bolt arrangements.Table 1 shows the outcomes of the calculations.Next, calculation and verification of the used fillet welds were performed.Table 2 shows the outcomes.

Fig. 2. Sizes and loads
The last stage was to evaluate the forces and tension for frame corner and to verify the stability of the column web.Calculation outcomes are shown in Table 3. Tensile load resistance amounted to 912.74 kN and bending resistance to 100.87 kN•m.effective design capacity of the bolt calculated by the program amounted to 27.69 kN.
Normal stress in a weld amounted to σ ⊥max = τ ⊥max = 72.72MPa, in the vertical weld to σ ⊥ = τ ⊥ = All the outcomes are compliant with the EN 1993-1-8 norm.Minor constructional changes, such as increasing the distance between the bolt and the edge and decreasing the size of the fillet welds ,were implemented.
Filled welds of the following size were used: column web weld a w = 4 mm, flange weld a f = 7 mm, stiffener weld a s = 4 mm and horizontal weld a fd = 5 mm.The loads put on a beam-to-column connection: • bending moment M d = 50 kN•m, • shear force V d = 10 kN, • axial force N d = 10 kN, • bending moment in the lower column M c1d = 50 kN•m, • shear force in the lower column V c1d = 10 kN, • axial force in the lower column N c1d = 10 kN.

Table 1 .
Calculations outcomes and bolt arrangement control

Table 2 .
Calculation outcomes and fillet weld control

Table 3 .
Engineer and control calculation outcomes for frame corner and column web