Foreword

TCVN 4613:2012 replaces TCVN 4613:1988.

TCVN 4613:2012 was converted from TCVN 4613:1988 in accordance with Clause 1, Article 69 of the Law on Standards and Technical Regulations and Point a), Clause 1, Article 6 of Decree No. 127/2007/ND-CP dated August 1, 2007 of the Government detailing the implementation of certain articles of the Law on Standards and Technical Regulations.

TCVN 4613:2012 was drafted by the Institute of Architecture, Urban and Rural Planning – Ministry of Construction, proposed by the Ministry of Construction, appraised by the Directorate for Standards, Metrology and Quality, and promulgated by the Ministry of Science and Technology.

1. Scope of application

1.1. This standard specifies the basic principles for representing steel structure drawings in technical construction design documents.

1.2. In addition to complying with the provisions in this standard, the representation of steel structure drawings must also comply with other relevant regulations.

2. Conventional symbols

The symbols for steel materials and connection types in steel structures are specified in Table 1.

NOTE: If symbols not included in Table 1 are used, they must be annotated on the drawings.

Table 1 – Conventional Symbols

Unit: millimeter

Symbol Name	Symbol
1. Equal-leg angle steel
2. Unequal-leg angle steel
3. I-beam steel
4. U-channel steel
5. T-shape steel
6. Z-shape steel
7. Round solid steel
8. Tubular steel
9. Square steel
10. Steel plate, steel sheet
NOTE: – These symbols are used to represent steel section profiles or member cross-sections; – The dimensions (a, b, B, h) and quantity of steel sections do not necessarily have to be represented in all cases; – When the number of steel section profiles of a member has been represented (e.g., +][), it is not necessary to indicate that quantity again; – In small-scale drawings, steel sections and plates may be represented by a bold line, but for I-beam and U-channel beam members, the rounded end of the cross-section must be represented.
11. Drilled hole mark
12. Oval (slotted) hole
13. Round hole with countersink on one or both sides (for assembly)
14. Countersunk rivet
15. Round head rivet
16. Floor anchor bolt
17. Temporary assembly bolt
18. Notched bolt for temporary assembly
19. Butt weld for assembly
20. Butt weld for fabrication
21. Lap weld for assembly
22. Lap weld for fabrication
NOTE: – The symbols from number 11 to number 22 are only used when representing the locations of drilled holes, bolt holes, and rivets; – The dimensions of the drawn symbols are based on the scale of the drawing, but the diameters of the holes range from 1.5 mm to 2.0 mm; – If the scale or dimensions of the drawing are too small to adequately represent the round hole symbols, they may be replaced by symbol number 11 (drilled hole symbol) at the corresponding locations; – On side views, holes along the longitudinal axis of bolts and rivets are represented by a thin short line corresponding to the axis; – In cases where holes need to be pre-machined before assembly, the hole diameter and bolt or rivet diameter must be clearly indicated. If the drilled hole is machined during assembly, only the hole diameter needs to be specified; – For symbol number 16 (Floor anchor bolt), the accuracy grade is written directly inside the circle, while the number only indicates the circle diameter dimension. – The alphabetic symbols written on the symbols in this Table must be replaced by numbers on the actual drawings. Where: a is the flange width of T-shape steel, side dimension of steel cross-section, in mm; b is the flange width of unequal-leg angle steel, in mm; c is the leg length of equal-leg angle steel, shorter leg length of unequal-leg angle steel, vertical leg height of T-shape steel, smaller dimension (thickness) of flat steel or steel sheet cross-section (for steel sheet, typically symbolized as δ), short axis dimension of oval hole, in mm; D is the diameter of round steel, diameter of drilled hole or reamed hole of machined part, in mm;d is the leg thickness of angle steel, in mm; h is the width of flat steel, strip steel, steel plate, steel sheet cross-section, in mm; N is the section number or dimension of the steel shape according to type; n is the quantity of a steel section type or dimension in the cross-section; m is the machining accuracy grade. – The diameters of the circles enclosing the part and component numbers range from 6 mm to 8 mm.

3. Provisions for drawing representation

3.1. The geometric diagram of the steel structure is represented in the working position with a small scale (1/50; 1/100; 1/200; …) and drawn in the most visible location on the first drawing of that structure (see Figure 1). The diagram is drawn with thin continuous lines representing the centerlines of the members.

NOTE:

1. The diagram does not show assembly details but must indicate the overall dimensions of the structure.
2. For roof truss structures, the member length values (in mm) and internal force values (in kN) are written directly on the diagram for each corresponding member – the internal force value is written below, the length value is written above.

Figure 1 – Geometric diagram of the steel structure

3.2. For symmetrical structures, it is permitted to represent the diagram of half the structure. If the structure is asymmetrical, the diagram of the entire structure must be represented.

3.3. The scales for representing steel structure drawings are specified as follows:

a) Geometric diagram: 1/50; 1/100; 1/200; 1/500;

b) Configuration representation: 1/20; 1/50; 1/100;

c) Detail representation: 1/5; 1/10; 1/20.

NOTE:

1. For very small details, a 1/1 scale may be used for ease of fabrication;
2. On the drawing of a single component, two types of scales are allowed: a small scale (1/50 or 1/100 or 1/200) for the member lengths and a large scale (1/5 or 1/10 or 1/20) for the member cross-section dimensions and connection details.

3.4. The following must be represented on the overall component drawing (see Figure 2):

a) The main dimensions of each part and overall dimensions based on the centerlines;

b) The lengths of steel members and their numbering sequence for each component;

c) The cross-sections of the steel members.

NOTE:

1. For connections and joints that need to be detailed at a larger scale, all dimensions, numbers, and sequence numbers must be indicated in a circle with a diameter of 8 mm to 10 mm (this circle is divided into two halves: the upper half contains the sequence number of the connection or joint; the lower half contains the drawing number that includes that connection or joint);
2. The reference numbers of steel members and components are written in circles with diameters of 6 mm to 8 mm;
3. For identical members or components in terms of dimensions and configuration, the same reference number is used, but for those symmetrical about an axis, the configurations must be drawn separately; in the material list, the note “forward” (F) or “reverse” (R) must be written next to the reference number to avoid confusion during fabrication;
4. For main members composed of multiple members, the cross-section must be drawn according to the actual composition used in the structural design calculations.

Figure 2 – Example illustration of a roof truss structure drawing

3.5. The following information must be clearly indicated on the structural drawing:

a) The dimensions necessary for fabrication, production, and erection;

b) The reference numbers of steel members, connections, components, and assemblies;

c) The symbols for assemblies and assembly surfaces (using uppercase letters – usually the first letter of the assembly name – and Arabic numerals);

d) The tensile and shear strengths of the steel types used for the structure;

e) The steel grades, welding rod types, weld strengths, weld heights, weld lengths;

f) The elevations of column tops, base plates, beam tops;

g) Points to note during component fabrication and erection;

h) The relationships between drawing sheets.

3.6. When representing complex structures, certain details such as connections, three-dimensional joints, etc. must be drawn separately. These separate detail drawings must include all necessary views, sections, and developed views to clearly represent the complex and hard-to-see parts (see Figure 3, Figure 4).

NOTE: Views looking from above are placed below; views looking from below are placed above; views looking from the left are placed on the left; views looking from the right are placed on the right.

LEGEND: Below each front view, a capital letter with an arrow indicating the direction must be marked.

Figure 3 – Example illustration of a steel structure detail drawing

Figure 4 – Example illustration of a drawing of a composite structure of round steel and steel sections

3.7. Steel structure drawings must include a material summary table presented as shown in Table 2 or Table 3.

Table 2 – Template for the summary table of steel types

Table 3 – Template for the steel classification table