As a new type of structure, whether the space frame structure can be promoted for a long time depends not only on the success of the technology of the structure itself but also on the space frame cost, which is more important than the traditional structure cost.
Compared with the traditional ordinary steel roof truss and brackets (old structure), Large span industrial warehouse space frame cost is relatively low. The process requirements of modern workshops with many production lines and the advantages of the space frame structure just happen to meet the process requirements for large column spacing. The industrial warehouse is 15m wide, consists of two spans of 24m+21m, and is 84m long. The column spacing of the central column of the old structure is 12m, and the column spacing of the central column of the space frame is expanded to 18m. A small number of cranes with a weight of 0.5~2t are hung on the roof. The space frame roof load is 180kg/m2, and the calculated steel consumption is about 22.7kg/m3 (excluding skylights), which is 26.1% less steel than the traditional ordinary steel roof trusses and brackets. The construction cost is 6.37% higher than the old structure.
For example, the use of GRC roof panels and the latest thermal insulation materials designated by the state will increase the investment of space frame roofs by RMB 140,100 (excluding the increase of RMB 14,100 in the upgrading of waterproof materials), an increase of 19.13%. However, if the utilization rate of the plant area is taken into account, it is estimated that it can be increased by 3%, and the investment in the roof is 7.78% higher than that of the old structure. If the locally developed roof panels and insulation materials are used, the roof investment of the space frame is only 3.01% higher than that of the old structure; if the utilization rate of the space frame workshop area is taken into account, it is estimated to increase by 3%, and the cost of the space frame roof will be saved. 8.61%.
Through calculation, it is found that the column spacing of the center column is 18m, which is an economical column spacing. Because the calculated column spacing of the center column is 15m, the amount of steel used is about 0.2kg/m2. Another feature of the space frame is that it has been considered in the calculation that the crane can be suspended in any plane position of the workshop to adapt to the development and change of the process. It has also been calculated that with the space frame plan with three spans of 15m+15m+15m and the column spacing of the center column is 15m, the steel consumption is reduced by 3. Aug/m2, and the investment of the space frame itself is reduced by 66,800 yuan.
The type of the above-mentioned space frame is a square pyramid. If there is no crane in the building, other space frame types that save steel can be used, which can further reduce the space frame cost.
In addition, for the calculation of the space frame cost in most cases, the installation cost of the space frame is an inevitable part， The following eight factors affect the cost of space frame installation:
The installation costs of the space frame are limited by many conditions, such as the unevenness of the site, whether the crane is used well, what is the construction plan of the space frame, the climate of the project location, etc.
♦The node form of the space frame: the most commonly used node forms are welded ball space frame and bolted ball space frame. Under normal circumstances, the installation cost of welded ball space frame is higher than that of the bolted ball;
♦Space frame size: the larger the space frame size, the lower the installation cost of the space frame;
♦The number of component specifications: the greater the number of specifications. The higher the installation cost
♦Elevation: The higher the elevation, the higher the installation cost of the space frame;
♦Site conditions: If the site conditions are good, and the hoisting equipment such as tower cranes and car cranes can achieve full coverage of the space frame, the general installation cost is lower;
♦The complexity of the shape of the space frame; the more complex the space frame, the higher the installation cost;
♦Questions about the span and column of the space frame: Obviously the larger the span and the same, the higher the installation cost;
♦Scheme: the more reasonable the construction scheme, the lower the installation cost.
Therefore, the cost control of steel structure space frame Industrial warehouse building has a direct impact on the realization of project economic benefits. In order to maximize profits and ensure engineering benefits, it is necessary to strengthen engineering cost control and management. Due to the huge amount of steel used and the high price in the process of engineering construction, it occupies a relatively large proportion of the engineering cost. Therefore, in order to effectively reduce costs and improve profit margins, it is necessary to strengthen the cost management of steel structure space frames, so the cost management of space frames is mainly From the following aspects:
1. initial preparation work
Because the preparation of the steel structure space frame project budget is related to too many sciences and fields, the preliminary work must be fully prepared so that the project budget can be effectively controlled. At the beginning of the project, it is necessary to fully understand the design principle and composition of the space frame, the materials used in several phases, the required equipment, the market, etc., to fully understand some overhead items, mainly including the cost of construction personnel and the cost of machinery and equipment. and material costs. In addition, because there will inevitably be some hidden safety hazards during the steel structure space frame engineering project, it is necessary to carry out an overall risk assessment and systematic analysis for the entire project. Also, understand the cost of quality. The cost requirements to ensure the quality of the space frame project, such as inspection expenses, etc.
2. Master construction drawings
Study the drawings of the steel structure project to understand the engineering quantity of the steel structure project. It has become the basis for the preparation of steel structure engineering budget, in which the engineering quantity is the core. The accuracy of the calculation of the engineering quantity plays a vital role in the engineering budget. Therefore, it is necessary to have a deep understanding of the drawings, and only when you truly master engineering and have a good understanding of the project can the accuracy of the engineering budget be effectively improved.
3. Bill of Quantities and Cost Pre-warning Price Review
The cost management personnel can timely point out the missing items and unclear places in the construction drawings during the drawing review stage, and final confirmation needs to be made before the bill of quantities is published. In the process of compiling the bill of quantities, the bidding entity needs to ensure that its data is clear and accurate, which can be calculated and measured, and try to avoid the phenomenon of ambiguity or lack of specific measures; it should also pay attention to the completeness of the bill of quantities, Eliminate the phenomenon of missing items and effectively prevent the construction unit from claiming or requesting design changes during the construction process. At the same time, in the process of cost early warning price review, the proportion of steel structure cost is relatively high. Therefore, it is necessary to strengthen the market inquiry comparison between steel plate and color steel plate materials to ensure the accuracy of cost early warning price.
4. Metered Payment Control
When carrying out the cost control and management of the light steel structure space frame workshop construction stage, it is necessary to install all items to measure and compile the measurement and payment control report, and the management staff needs to review the contractor’s measurement and payment certificate and other qualifications to prevent the occurrence of excessive measurement during construction. the situation, leading to the existence of the overpayment. At the same time, the effective management and control of on-site engineering measurement and payment is completed, and the measurement and payment links are separated and handled separately by different personnel. In the future, all measurement and payment-related documents need to be signed by the person in charge of the contractor, the construction agency, and the supervision unit. When carrying out the measurement of foundation, original ground, and concealed works, it is necessary to conduct joint measurements of three parties, so as to effectively ensure the accuracy and fairness of on-site measurement work.
5. Control of space frame engineering changes
During the construction process, due to the influence of the owner or the limited construction of the specific site, design changes will occur. If there are multiple changes, the total project cost will be affected. Therefore, in the early stage of each design change, it is necessary to complete the discussion on the increase and decrease of the engineering quantity and cost, and submit it to the original design unit for feasibility determination. For the engineering cost control in the design change link, it is necessary to conduct a detailed review of the increase of the design content and the improvement of the design standard, so as to avoid an excessive increase in the engineering cost. The review of engineering changes needs to strictly follow the requirements of saving construction funds and resources, speeding up the construction speed, and improving the quality of the project, and at the same time, it can better meet the relevant requirements of society, and the environment, and economy.
6. Improve the effectiveness of cost management
Having reached a high level of cost control of steel structure projects, we must pay attention to whether the means of cost control are reasonable and effective. Steel structure projects have dynamically changing properties, so it is necessary to start from the whole project, and the overall engineering personnel must think about it and formulate a comprehensive control method for the overall steel structure project. First, we must consider the overall cost control of the project. For each stage of the project, generally including project report analysis, architectural design, project development, and acceptance after the project is completed, the cost control idea must be considered. , In any period, we should pay attention to cost control and establish a sound and perfect cost management system.
7. Cost Management in the Completion and Settlement Stage of space frame Project
In the completion and settlement stage of the steel structure, it is necessary to start from the supervision of the relevant materials provided by the construction enterprise. The supervision unit needs to cooperate with the project cost control personnel to conduct a preliminary review and issue an audit report of the supervision completion final account. At the same time, in the final accounts of completion, it is necessary to check the project bidding documents, contracts, and other materials with the specific construction materials and engineering quantities, confirm the cost of the visa form and the contact form, and verify the engineering quantity with the engineering records, and submit the results. Among them, if the project quantity is not completed according to the construction drawing requirements or the project quantity change is not completed according to the relevant standards in the specific operation process, the cost shall be reduced; in the contract, the relevant conditions for the project cost and risk cost are stipulated in the contract, if they appear in the contract Disagreement will require a fee reduction. In the process of settlement review, it is necessary to ensure the rigor of the work, so as to effectively prevent the occurrence of repeated settlement and other situations, so as to control the project cost to the greatest extent.