It is estimated that the measurement of reinforcement engineering is a "nightmare" for every beginner of business cost.
I remember that around 1999, a large residential project did not have efficient measurement tools such as measurement software. At that time, the 96G101 atlas of flat method construction was just launched. Before the implementation of flat method construction, the design institute generally had detailed drawings of reinforcement nodes and reinforcement lists, and even marked the details and weight of reinforcement on the drawings in the form of tables, The calculation of steel bars is relatively simple. If we want to find the hand drawn blueprints of the past, we may have to go to the archives to find them.
The implementation of steel bar flat method construction has doubled the efficiency of the design institute, but it has added a lot of burden and trouble to the construction company. To calculate the steel bar, the first step is to go through the flat method construction atlas. I turned over 96G101 once in the year, and wrote several large manual calculation drafts, but now I have forgotten all about it. Moreover, the flat method atlas has changed many versions, and I am also a "little white" for the reinforcement engineering.
The article pushed today is that we have been working as reinforcement engineers for 23 years, and we have worked together for more than 10 years. In the project, I "forced" him to use software to proofread, which greatly improved efficiency, facilitated review, calculation and plan making than he did by hand. Later, I "forced" him to use graphic calculation software. Now he is not only an expert in reinforcement engineering, It can also be called an expert to use graphics to calculate quantities.
A week ago, I asked him to write this article about the measures he had been troubled with. It really benefited a lot. I would like to share it with you.
Although the measure reinforcement is not a load-bearing reinforcement in the structure and does not need design calculation, it is necessary to ensure the project quality and the accurate placement of the load-bearing reinforcement in the actual project. In the project settlement, the calculation of measure reinforcement can refer to 11G902-1 atlas as the basis.
1. Purpose and type of measure reinforcement
As the skeleton of the whole building, the accuracy of the position of the reinforcement is directly related to the safety of the structure. If the protective layer of the reinforcement is too small, it will be corroded due to the impact of the external humid environment, and the deviation of the reinforcement will become a lifelong hidden danger that cannot be remedied. Therefore, in order to ensure the accurate layout of the stressed reinforcement, the use of measure reinforcement is essential. In the actual project, there are several kinds of measure reinforcement with large amount and common use, as shown in the figure
1.1 stirrup
As a measure reinforcement for floor slab and foundation raft construction, stirrup reinforcement is indispensable, not only for on-site construction but also for engineering cost measurement.
In the actual construction process, in order to ensure the effective height of the reinforcement of the floor slab and foundation raft, fix the upper layer reinforcement mesh, and ensure that the protective layer of the upper layer reinforcement is within the specified specification range, usually a full-length stirrup bar is set between the two layers of reinforcement mesh, and the diameter of the stirrup bar is not less than the diameter of the upper layer load-bearing bar.
If the thickness of the foundation plate is greater than 800 mm, stirrup bars should not be set, and steel brackets welded with angle iron should be placed to ensure the upper reinforcement load and construction load. The specific construction method shall be in accordance with the special construction scheme for reinforcement prepared by the construction unit.
As shown in the figure below:
The raft and the horse stool reinforcement in the floor slab arranged in two directions with two nets shall be arranged in full length according to the row spacing of S=1000mm, and the distance between the first row and the last row of horse stool reinforcement and the slab edge is S/2.
Each row of horse stool bars shall be placed according to the clear length of the plate. Two adjacent horse stool bars in the same row shall overlap each other by 100mm: for the structure with only negative bars, horse stool bars shall be arranged as follows. When the length of the negative bars extending into the plate is less than or equal to 1500mm, a row of horse stool bars shall be placed under the negative bars; When the length of the negative reinforcement extending into the plate is more than 1500mm, the horse stool reinforcement shall be arranged according to the row spacing S=1000mm; The distance between the support edge and the bend of the horse stool reinforcement is S/2, and horse stool reinforcement may not be arranged in the intersection area of vertical and horizontal negative reinforcement.
As shown in the figure below:
1.2 Ladder bar and top formwork rod
In the process of binding the shear wall, in order to ensure the distance between the reinforcement mesh of the shear wall and the spacing between the protective layer of the shear wall and the horizontal reinforcement, the vertical and horizontal ladder reinforcements are usually used. Refer to 11G902-1 atlas as the basis.
The horizontal ladder reinforcement controls the spacing of vertical reinforcement, the row spacing of vertical reinforcement, and the thickness of protective layer of load-bearing reinforcement. The horizontal ladder bar shall be set in the wall with three layers of upper, middle and lower bars, and shall be replaced by the one larger than the original wall horizontal bar. The horizontal ladder bar shall extend into the concealed column or frame column for 15d.
The vertical ladder reinforcement controls the horizontal reinforcement spacing and the thickness of the protective layer of the load-bearing reinforcement. The spacing of vertical ladder reinforcement is 1.5m, and the reinforcement of the original wall vertical reinforcement with a larger specification is used instead. The vertical ladder reinforcement is added with a top formwork rod. As shown in the figure below
The end of the top formwork rod used for top formwork shall be straight and painted with antirust paint. The antirust paint shall be painted 1cm inward from the end. The length is - 2mm of the wall thickness. The spacing between the top formwork rods is 900mm * 900mm. The diameter and spacing of the reinforcement of the top formwork rod shall be determined according to the scheme prepared by each construction unit.
As shown in the figure below:
1.3 Column longitudinal reinforcement positioning frame
Locating frame is used to limit the longitudinal main reinforcement of the shear wall concealed column of frame shear wall structure or the frame column of frame structure. Generally, one locating hoop is set for each floor.
As shown in the figure below:
When there are multiple rows of steel bars on the upper and lower parts of the beam, it is necessary to place sizing blocks between the multiple rows of steel bars to ensure the distance between the longitudinal bars. The upper part is based on the length of each row of support bars extending into the span. The spacing between sizing blocks is 1500 mm, the diameter of sizing blocks is d (and not less than 25 mm), and d is the maximum diameter of the longitudinal load-bearing steel bars of the beam.
The lower sizing block shall be considered according to whether the lower reinforcement extends into the support. If it extends into the support, it shall be calculated according to the clear span of the beam. If it does not extend into the support, it shall be calculated according to the length not extending into the support. The sizing block length is the beam width minus 2 protective layers.
As shown in the figure below:
The beam positioning reinforcement is mainly used to control the position of the load-bearing reinforcement of the beam not to shift when pouring concrete, so as to ensure that the position of the beam section size is accurate and the corresponding positioning reinforcement is made according to the section size of each beam.
The method is shown in the figure below, and the horizontal reinforcement is 25; The diameter of toothed short rebar is 14mm, and the length is 5cm. The diameter of positioning bar reinforcement shall be determined according to the reinforcement construction scheme prepared by each construction unit.
2. Basis for calculating measure reinforcement
If the national standard list pricing code is used for pricing, according to the provisions in P41 of the Code for Calculation of Quantities of Housing Construction and Decoration Works (GB50854-2013), the supporting reinforcement at the fixed position in the cast-in-place component, the anchor reinforcement of the "iron horse" protruding from the component for the double-layer reinforcement, the hook of the prefabricated component, etc., shall be included in the reinforcement quantities.
One thing to note is that if it is not specified in the design, the quantity shall be confirmed by site visa during construction, and shall be calculated according to the site visa quantity during settlement.
If the quota pricing method is adopted, the only basis for calculation of the amount of measure reinforcement used by both parties is the special reinforcement construction scheme jointly signed and approved by the construction party, the construction party and the supervision unit. Therefore, the construction company must prepare a special construction plan for reinforcement before construction, and the plan should be detailed without omission.
For example, it is stipulated in Article 5 of Reinforcement Works on Page P82 of Volume I of 2016 Budget Pricing of Tianjin Construction Engineering that the measure reinforcement in reinforcement works shall be calculated according to the requirements of design drawings, construction acceptance specifications and approved construction organization design, and the corresponding items shall be implemented according to the variety and specification. If other materials are used, they shall be calculated separately.
As for the measurement and pricing mode that adopts non national standard specifications or quota mode, it depends on the contract and technical parameter conditions. Some clear measure reinforcement is placed in the measure cost and quoted separately from the solid reinforcement. The difference between the quantities of work and the price of steel cannot be adjusted, such as the agreement of a project:
