Steel structure engineering quantity calculation and quotation key points

Steel structure engineering quantity calculation and quotation key points

Part I drawings

1、 Drawings: according to the drawing catalogue, clear and check the number of drawings and check whether there is any omission.

2、 Construction drawings

1. General description of design

(1) Construction area, structural form, column spacing, span and structural layout; (2) scope of engineering quantity calculation: clear the scope of bidding quotation for structure, roof, wall, doors and windows; (3) material selection, specification, model and technical requirements; (4) oil paint or coating requirements and fire protection grade of steel structure. 

2. Layout, elevation and section:

The quantities of doors and windows, indoor and outdoor steel ladders, roof color plates, daylighting panels, wall color plates, roof ventilators, canopy, downpipes, edge closing and flashing parts, gutters, etc. can be counted.In statistics, the material, specification and model of each material shall be indicated.

Structural construction drawing

1、 General description of structural design

(1) Material: the material corresponding to each part (steel column, beam, purlin, support, etc.), such as Q235, Q345, strength grade requirements of high-strength bolts, etc. (2) welding quality requirements: weld quality grade, NDT requirements, such as splicing weld quality grade should reach grade I, 100% flaw detection is required, and 20% flaw detection for secondary weld is required, which involves the calculation of NDT cost.(3) Derusting requirements: manual and power tool derusting (st), spray or ejection derusting (SA).The cost of rust removal is different for different derusting grades.(4) Paint (coating) requirements: paint type, painting times, paint film thickness, fire rating, fire resistance limit of each part. 


2、 Layout, elevation, section and node details:

1.The following quantities can be calculated in turn:

(1) Embedded iron parts: including embedded positioning plate, embedded bolt and nut; (2) steel column, wind column, steel beam, crane beam; (3) roof support, tie bar, column support, canopy framework; (4) roof purlin, wall purlin, corner brace and pull rod of roof and wall purlin; (5) during calculation, pay attention to the calculation of crane beam and column connector, base plate, roof and wallFor the quantities of surface purlin supporting plate, connection plate between corner brace and steel column and beam, steel sleeve of diagonal tie rod, etc., the quantity of high strength bolts shall be counted. 

2. If there is a material list in the drawing, the size, specification and quantity of the parts in the list can be checked in turn according to the part number listed in the material list, and whether there are missing, missing and wrong calculation.

3. Pay attention to whether there are design changes and modifications, supplementary instructions, Q & A, etc.

Matters needing attention in calculation

On the format of engineering quantity calculation 

1. The weight unit of steel structure is kg, the unit of area is m2, and the unit of length is m. The calculation results are all kept to one decimal place.

2. When calculating the weight of components, the parts of components can be numbered from bottom to top, from left to right, and calculated in this order.

3. The format of the formula is as follows:

(1) Plate: Specification × length × width × quantity, for example – 6 × 500 × 300 × 5, it means that the plate thickness of the part is δ = 6 mm, the plate length is 500 mm, the width is 300 mm, and the quantity is 5 pieces.The weight calculation formula is: 6 × 0.5 × 0.3 × 7.85 × 5 = 35.3kg (2) profile: specification, length × quantity × specific gravity, for example, L50 × 5, l = 3500mm × 5 × 3.77, which means equal leg angle steel with a limb width of 50mm, length of 3500mm, quantity of 5 pieces and specific gravity of 3.77kg/m.The weight formula is: 3.5 × 5 × 3.77 = 66.0kg

2、 Some points for attention in calculating dimensions

1. Pay attention to the elevation value of indoor and outdoor and steel column bottom plate, whether it is ± 0.00 or other elevation values.When the length (or height) is calculated by elevation value, special attention should be paid not to be calculated as ± 0.00.2. The calculation of the height (or length) of stiffening plate, purlin corner brace and parapet eaves bracket corresponding to variable H-section members (beams and columns) can be calculated according to the average H-section height of beams and columns.3. The length of roof purlin shall be calculated according to the full length without deducting the gap between purlins. In addition, the length of purlin occupied by roof beam at gable shall be added. For example, if the axis represents the center line of roof beam, then: purlin length = axis length + roof beam width.4. In the calculation of wall purlins, attention should be paid to whether the door posts and door beams are double purlins, and whether there are double purlins in other parts.5. The length of the tie rod is calculated by adding 50 mm to each end of the corresponding purlin spacing, and the length of each tie rod is increased by 100 mm.

6. Calculation of edge closing and flashing

(1) Calculation scope: roof ridge cover plate, flashing board at the interface between gutter and roof panel and parapet, flashing board at the interface between gable and roof panel, coping flashboard on the upper part of parapet, edge closing plate at wall corner, edge closing plate around doors and windows, flashing board at the junction of wall panel and brick wall, flashing board at the junction of wall and canopy, and edge closing plate around canopy.If it is a double-layer plate, the edge closing parts at the joints of roof inner plate and wall inner plate shall be calculated separately.(2) About the width of the edge closing flashing plate: Generally speaking, the expanded width of the edge closing flashing part can be calculated as 300 ~ 400mm, and the unfolded width of parapet coping and roof ridge cover plate is calculated as 500 ~ 700mm.In the actual calculation, it can be calculated according to the corresponding contact details. 

7. For the web of variable cross-section beam and column, the weight shall be calculated according to the net weight in bidding, subcontracting settlement and cost calculation, and shall be calculated according to the external rectangle when handling the settlement with Party A.All kinds of connecting plates are calculated as external rectangle. 

3、 Parts that cannot be recalculated

1. High strength bolt: the connection between column and beam and the connection between crane beam are shared by two components, and one component cannot be calculated once.2. Roof support, tie bar, column support: some construction drawings show the partial layout of roof support in the column support drawing, but it has been calculated in the calculation of roof support, so it should not be calculated again. In this case, the drawings of roof support and wall support should be compared.

4、 Other precautions

1. When calculating the specific gravity of profile, especially H-beam and steel pipe, do not forget to reduce the thickness.For example, when calculating the specific gravity of steel pipe, do not calculate it as round steel, but subtract the area occupied by inner diameter.2. When referring to the specific gravity of the materials in the hardware manual or other materials, be sure to read them clearly and do not make mistakes.3. The specific gravity of C-type purlin can be calculated according to the developed area.4. The framework of hollow sunlight board, aluminum plastic plate and other decorative surface materials should not be omitted.5. All calculation processes should be careful and careful, and should not be careless. In general, the calculation should be checked twice.We should bear in mind the saying that “a mistake is a thousand li”.If the calculation accuracy is low or there is error, the consequence will be very serious.In addition, we should not be ashamed to ask questions, be open-minded and eager to learn; we should often go to the front line of the project, understand and be familiar with various construction technologies and processes, deepen our impression, and lay a foundation for better budget and settlement work.

Post time: Jul-04-2020