Two calculation methods of capping beam
The traditional simplified algorithm of 1
Represented by Qiaotong.
Direct loading method of influence line of two-cap beam
Represented by Dr. Bridge.
Calculation and drawing of bridge capping beam
Calculation principle of a capping beam
(1) Based on the current bridge and culvert specifications issued by the Ministry of Communications.
⑵ The span of the skew bridge is calculated according to the skew length of the bridge hole and the orthogonal bridge method.
(3) Calculate the load reaction along the bridge direction according to the simply supported beam loading.
(4) The lateral distribution coefficient is symmetrically distributed according to the lever method, and the eccentric load is symmetrically distributed according to the rigid beam method.
5] When the span is three or more, the capping beam is regarded as a double cantilever multi-span continuous beam with rigid support, and when the span is two, it is a double cantilever simply supported beam.
[6] The influence lines of column (rib) supporting reaction and internal force of each calculated section are established.
Once the transverse load is transferred to each beam (plate) through transverse distribution, then each beam (plate) is loaded according to the internal force influence line, and the most unfavorable internal force value caused by people, vehicles and trailers on each calculation section is obtained.
Being combined with load internal force, find out the maximum and minimum internal force of each calculated section, and form an internal force envelope diagram.
Levies The bending moment controls the strength of normal section and the number of main reinforcement, the shear force controls the shear strength of inclined section and the number of inclined reinforcement, as well as the spacing and number of stirrups, and the cracks are controlled by the bending moment.
Second, the drawing principle
(1) According to the overall dimensions of the capping beam, calculate and determine the drawing proportions of the steel structure drawing in the longitudinal and transverse directions respectively, increase or decrease the drawing proportions by 2, and calculate the control coordinates of the elevation, plane, side and reinforcement details at the same time.
⑵ The number of reinforcement is calculated according to the skew angle, the type of bent reinforcement, the number of stirrup turns, the height of capping beam or the elevation of cantilever section.
(3) Draw the elevation, plan, profile and details of the reinforcement, and calculate the number and length (including average length) of the reinforcement.
(4) Calculate and draw the steel bar list, material quantity list and D value list of bent steel bars.
5] Generate *. SCR reinforcement graphic file. Users can display, edit and modify on the screen after entering AutoCAD graphics platform, and output with plotter.
Three-cover beam design
1 Use of template files
The system provides users with template files named n2.qlt and n3.qlt. 1 completed, corresponding to 2-column and 3-column capping beam structures respectively. This data file can be calculated and drawn.
2. Establish the user project file name
There are two methods, one is "Create Project" under the drop-down menu of project management in the main menu of bridge access, and the other is "Open File" under the drop-down menu of "Calculation and Drawing of Pier Cap Beam" in the main menu of bridge access.
3 Enter the cap beam size.
Open the drop-down menu of Bridge Pier Calculation and Drawing, and the data entry form of Bridge Pier Calculation and Drawing will pop up. Select the capping beam calculation, click the "capping beam size" button, and the data entry form will pop up. Enter the basic data of capping beam according to the prompt, and the data entry is finished.
Close the form.
4 Input upper cross-sectional data
Click the "Cross Section" button to open the data entry form, enter the basic data of the upper section according to the prompts, and close the form after data entry.
5 input design data
Click the "Design Data" button to open the data entry form, enter the basic data of design data according to the prompts, and close the form after data entry.
6. Generate the capping beam discrete diagram.
Run "Generate capping beam discrete diagram", the user inputs AutoCAD R 14, and after the command item, type script+space+file name, then the capping beam discrete diagram can be displayed on the screen, and the user can check whether there is any error in data input according to the drawing.
7 input capping beam material
Click the "gland material" button to open the data entry form, enter the basic data of gland material according to the prompt, and close the form after data entry.
8 Enter the design check
The size optimization of the capping beam depends on the section size of the capping beam, the number of columns, the spacing between columns and the upper load. Generally speaking, the design to ensure that the positive and negative bending moments of the capping beam are close is reasonable. How to realize it? Users only need to click "Design Check" to pop up the design check form, and select the left buttons "Cap Beam Size", "Cap Beam Material", "Upper Section" and "Design Data" to modify the data, and then confirm and save. Click Calculate and Generate Cap Beam Envelope Diagram to display the envelope diagram dynamically in the drawing area immediately. If it does not meet the designer's requirements, after saving the modified data, click "Calculate and generate capping beam envelope diagram".
9 browse and print the capping beam calculation.
Close the design check data, click the "Browse capping beam calculation results" button, and select the project file name. At this point, the browsing result form is displayed in the center of the flat screen, and designers can quickly browse the calculation results of capping beams. If the designer wants to browse the transverse distribution coefficient of beam and slab, he only needs to click the "transverse distribution coefficient" button, and if he wants to browse the internal force combination result of capping beam, he only needs to click the "internal force combination" button. Designers can also open the calculation results of another project, click "two different calculation books" first, and then open another calculated calculation book. You can view and compare two different calculation results at the same time. Users can also click the print button to print out the calculation results of capping beam for archiving and future reference.
10 generates the moment-shear envelope diagram and crack reinforcement diagram.
Enter AutoCAD R 14, and type script+ file name after the command: view or draw the bending moment, shear envelope diagram and crack reinforcement diagram. (omitted here)
1 1 Generate reinforcement data of reinforcement structure diagram.
After the design data is confirmed, the user can click "Generate rebar drawing data". At this time, a dialog box will pop up, prompting the user which pier number position the reinforcement data automatically generated after calculation should be stored in. The user must click the dock number with the mouse. For example, Purnot. Now the design is 1. If Purnot. 1 This project is designed for the first time, and pierNo is adopted. 1 will be selected as the data for storing steel bars. If the reinforcement diagram of this project 1 pier has been designed, then don't choose this project 1 pier. Otherwise, the original reinforcement data of 1 pier will be overwritten by the reinforcement data generated by the design. In this case, it is best to choose a larger pier number (such as pier 99) to store the automatically generated reinforcement data after calculation. If 1 pier needs these data, you can use the insert function to insert the reinforcement data of pier 99 into 1 pier.
12 Enter or modify rebar data.
Click "capping beam drawing" mode, and then click "rebar data" to open the capping beam rebar data input dialog box, where users can enter and modify rebar data. After modifying all the data, click the "rebar data check" button, and the system will judge the correctness of the rebar data of the capping beam until the prompt is correct. Some tips, such as 10mm for the diameter of side reinforcement and I-grade reinforcement, will prompt an error or warning when the diameter of reinforcement input by the user is greater than 10mm and the reinforcement grade is II-grade reinforcement, which can be ignored by the user, and a reinforcement diagram can still be generated.
1) Enter or modify capping beam material, protective layer, stirrup spacing and encrypted data.
After the data input dialog box of capping beam reinforcement pops up, click "capping beam material, protective layer, stirrup spacing, encryption", and users can input and modify relevant data. When the modification is finished, click Save to save the file.
2) Input or modify the data of upper and lower reinforcement, short reinforcement and bending reinforcement.
After the data input dialog box of capping beam reinforcement pops up, click "Up and down reinforcement, short reinforcement and bending reinforcement", and users can input and modify relevant data. After modification, click the "Save" button to save the file. When the data to be input is blocked by the schematic display box, you can move the schematic display box and edit the data.
3) Enter or modify the data of section reinforcement. After the data input dialog box of capping beam reinforcement pops up, click "Section Reinforcement", and users can input and modify relevant data. When the modification is finished, click Save to save the file. The rebar at the lower edge is represented by X. When the rebar number is 2 digits, rebarNo. 10 is represented by A, rebarNo. 1 1 is represented by B, rebarNo. 12 is represented by C, and rebarNo. 13 is represented by D.
4) Enter or modify the steel skeleton data. After the data input dialog box of capping beam reinforcement pops up, click "Skeleton Reinforcement" (note that the number of reinforcement skeletons in "Basic Data" must be greater than 0), and users can input and modify relevant data. When the modification is finished, click Save to save the file.
13 Description of rebar data and rebar cross section data
The number of straight-through bars at the upper edge and the number of straight-through bars at the lower edge can be the same or different.
The number of pieces of steel skeleton composed of upper and lower steel bars can be 0 or more. When it is greater than >: 0, its value n refers to the steel skeleton composed of n pieces of upper and lower steel bars and short diagonal bars. At this point, you need to enter:
The number of short diagonal bars of each steel skeleton on the left side of the side column nbzl = 4；;
The distance between the short diagonal reinforcement of each reinforcement skeleton on the left side of the side column and the center of the side column dbzl = 50,90, 130,170;
The number of short diagonal bars in each steel skeleton on the left and right sides of the side column nbzr = 4；;
The distance between the short diagonal bars of each steel skeleton on the right side of the side column and the center of the side column dbzr = 40,80, 120.
If it is 3 columns and 4 columns, continue to read in the following short diagonal reinforcement number and offset.
The number of short diagonal bars of each steel skeleton on the left side of the center column NZZL = 4；;
Distance DZZL = 55,95, 135,175 between the short diagonal bars of the steel skeleton on the left side of the middle column and the center of the side column;
The number of short diagonal bars of each steel skeleton on the left and right sides of the center column nzzr = 4；;
The distance between the short diagonal bars of the steel skeleton on the right side of the center column and the center of the side column dzzr = 45,85,125;
The number of bent steel bars (≤ 12) thunder. XING=4，
The middle distance (cm) of the upper and lower rows of steel bars cm)= 2.7；;
Steel bar bending of mid-span section is adopted, where 0 is inclined steel bar bending of mid-span, and 1 is normal section bending of mid-span. Many designs or standard drawings generally use 0-span middle part, which makes the steel bar bend obliquely downward. When the skew angle is large, 1 can be used to bend down the midspan normal section.
Enter the number and offset of bending steel bars:
Number of sidebars from the right side of the sidebar to the left side of the middle bar to the right side of the middle bar.
D 1 D2 D3 D4 (cm)
ND2=2， 123， 13 1， 13 1， 13 1，
ND3=2， 123， 13 1， 13 1， 13 1，
ND4=6，67，7 1，
ND5=6， 1 1， 1 1， 1 1， 1 1，
If d 1
If D2
If D3
If D4
If D 1=0, D3=0, D4=0, the lower edge of the finger is provided with through steel bars.
d 1 & lt； 0 or D3
When D 1=-999, it means that it is not bent at D 1, and the meaning of D2 value is shown in the figure. (Features will be added)
Stirrup ring number huan = 3;
The number of steel bars dominated by side stirrups NKB = 6；;
The number of tendons dominated by the middle stirrup (read in when the ring is 3) NKZ = 8；;
Huan = 1, =5, = 0; Huan =2, =5 and = 0; Huan =3, =5, =6
Mid-span stirrup spacing (cm) a1=18;
Spacing of stirrup of cantilever part (cm) A2 =16;
Transverse rib spacing (cm) a3 =18;
The number of reinforcement stirrups outside the side column is m1=10;
The number of encrypted stirrups inside the side column m2 =10;
Dense stirrup spacing m3 =10;
The following is the steel bar section data.
The maximum number of steel bars in each row in the section is 24.
The number of reinforcement rows on the upper edge of the side column section is at most 3 rows, and the single column can reach 6 rows.
The number of the first, second and third rows of steel bars on the upper edge of the side column section. If there are no steel bars, fill in 0, and the number of digits is equal to NP.
The number of steel bars at the lower edge of the side column section is at most 3 rows, and the steel bars at the lower edge can be represented by X.
The number of the first, second and third rows of steel bars at the lower edge of the side column section. If there are no steel bars, fill in 0, and the number of digits is equal to NP.
The number of reinforcement rows at the upper edge of mid-span section is at most 3 rows, and the value-1 is the same as the reinforcement arrangement at the upper edge of side column section.
The number of the first, second and third rows of steel bars at the upper edge of the mid-span section. If there are no steel bars, fill in 0, and the digits are equal to NP.
The number of reinforcement rows at the lower edge of mid-span section is at most 3 rows, and the value-1 is the same as the reinforcement arrangement at the lower edge of side column section.
The number of the first, second and third rows of steel bars across the middle and lower edges. If there are no steel bars, fill in 0, and the number of digits is equal to NP.
The number of rows of steel bars on the upper edge of the central column section is at most 3 rows, and the value-1 is the same as the arrangement of steel bars on the upper edge of the side column section.
Number of steel bars in the first, second and third rows on the upper edge of the middle column section; If there is no reinforcement, fill in NP such as 0 and numbers.
The number of reinforcement rows at the lower edge of the central column section is at most 3 rows, and the value of-1 means that the reinforcement arrangement at the lower edge of the side column section is the same.
Number of steel bars in the first, second and third rows at the lower edge of the central column section; If there is no reinforcement, fill in NP such as 0 and numbers.
Calculation and drawing of bridges
This example mainly introduces the process and method of calculating the pier capping beam by Dr. Bridge, focusing on the loading treatment of the live load of the virtual bridge deck capping beam.
The capping beam calculation mainly includes the following steps:
Structural dispersion of pier capping beam (division unit)
Enter overall information
Enter unit information
Enter building information
Enter usage information
Perform project calculations
Consult the calculation results
This sample tutorial pier structural parameters
1, discrete structure
Firstly, the capping beam is discretized, that is, the capping beam model is established by dividing units. The principle is that nodes must be set at the bearing, column top and characteristic section (mid-span, 1/4). If you need to consider the frame function of pier and capping beam, you need to build pier. The boundary conditions at the bottom of the column depend on the situation. If it is connected by integral bearing platform or tie beam, it can be regarded as column bottom consolidation. If it is a pile without tie beam, elastic bearing or equivalent model can be used to simulate the pile.
Step 2 Enter the overall information
The calculation type is: safety calculation of the whole bridge structure
Calculation content: Check and calculate live load.
Bridge environment: the relative humidity is 0.6.
Specification selection CCCC 04 specification.
3. Input information unit
Input the unit information and establish the unit model of pier, capping beam and cushion stone. For T-beam or small box beam, because the bearing spacing is relatively large, the wheels cannot directly act on the cover beam. We also need to set a virtual bridge deck unit on the capping beam to simulate the lane surface and connect it with the capping beam through the master-slave constraint. The stiffness of continuous beam on virtual bridge deck is at least 100 times greater than that of capping beam. The model is established as follows:
When the virtual bridge deck is a continuous beam, the stiffness can be modified in the characteristic coefficient.
4. Enter building information
The first construction stage: install all the bars.
Add boundary conditions
Add the master-slave constraint of virtual bridge deck and capping beam: the master-slave constraint of virtual bridge deck and capping beam needs to simulate two situations of virtual bridge deck simply supported beam and virtual bridge deck continuous beam; These two methods are lever method and eccentric compression method in the Manual for Simulating Pier and Abutment. Its purpose is to control the positive bending moment section by lever method; Control of negative bending moment zone by eccentric compression method.
For the virtual bridge deck continuous beam to simply supported beam, nodes and corresponding master-slave constraints are added to the virtual bridge deck unit corresponding to the bearing.
The second construction stage: adding permanent load. If the deadweight system is 0, you need to add the deadweight of the capping beam.
5. Enter usage information
This paper mainly introduces the treatment of live load of capping beam. For hollow slab beams, because of the small bearing spacing, the capping beam can be directly used as a bridge deck unit without setting a virtual bridge deck. When using Dr. Bridge, the program has the function of automatic lateral loading. Users only need to input the maximum reaction force of a single train into the lateral distribution adjustment coefficient, and input the driving range and crowd loading range of the vehicle into the effective area of lateral loading, so that two wheels of the vehicle can be loaded within the driving range.
Open the live load input dialog box and input the maximum reaction force of a single train into the lateral distribution coefficient (at this time, the lateral distribution coefficient is no longer the real lateral distribution coefficient, but the force exerted by the train (or trailer) on this lateral structure. Please refer to page 80 of Dr. Bridge's User Manual for details).
Check the lateral load, and input the effective area of lateral load of vehicles and personnel:
Fill in the crowd concentration and sidewalk width in the live load input dialog box 1, because the crowd concentration and width have been considered in the crowd load reaction and lateral load area.
6. Perform project calculations
After the model is established, the engineering calculation is carried out.
7. Check the calculation results
View the required calculation results.
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