A comprehensive and detailed summary of the basic principles of steel structure

Review and summary of basic principles of steel structure One ． Completion 1、 The most important factor affecting the fatigue life of structures is the structural state 、 Cyclic load and cycles . 2、 The mechanical property index of steel is yield strength 、 Tensile strength 、 Elongation 、 Cold bending performance 、 Z Shrinkage rate and Impact toughness . 3、 The position of the load action point has an influence on the overall stability of the beam , Relative to the load acting on the tensile flange of the I-section simply supported beam , When the load acts on the compression flange of the beam , The overall stability of the beam will Reduce . 4、 A simple supported beam with I-shaped composite section , If the height thickness ratio of the web is 100, Should be set The transverse Stiffener , If the web height thickness ratio is 210, Should be set The longitudinal Stiffener . 5． Steel contains C、P、N、S、O、Cu、Si、Mn、V Equal elements , among N、O For harmful impurity elements . 6、 In axial compression members , Determine the width of the box section plate to meet the local stability （ high ） The principle of thickness ratio limit is that the plate will not buckle locally before the member stress reaches yield （ Or the local buckling critical stress is not Below yield stress , Or not before yielding ） , Determine the I-shaped section and the plate width （ high ） Thickness ratio limit The principle of value is There is no local buckling of the plate before the overall buckling of the member （ Or the local buckling critical stress is not Lower than the critical stress of global buckling or equal stability or not prior to global instability ） . 7． The main index to measure the plasticity of steel is Elongation . 8. The three embrittlement of steel refers to Hot crisp 、 Cold and crisp 、 Blue crisp . 9. The five mechanical properties of steel are yield strength 、 Tensile strength 、 Elongation 、 Cold bending performance 、 Impact toughness . 10． For lattice columns with batten plates , The condition of single limb stability is The single limb stability bearing capacity is not less than the overall stability bearing capacity , And not more than Allowable slenderness ratio . 11． The batten of batten lattice column is designed according to Axial force Component calculation . 12． For batten lattice columns , The condition of single limb stability is The single limb stability bearing capacity is not less than the overall stability bearing capacity . 13. The strength of thin plate is slightly higher than that of thick plate high .

14． The minimum calculated length of fillet weld shall not be less than

​

Add picture comments , No more than 140 word （ Optional ）

and Weldment thickness .

15． The maximum effective length of side fillet weld under static load is

​

Add picture comments , No more than 140 word （ Optional ）

.

16． In bolted connection , The minimum end distance is 2d0 .

17． In bolted connection , The minimum bolt distance is 3d0 .

18． Common bolted connection , When the thickness of the plate stack ∑t〉5d when (d－ Bolt diameter ), Connections may produce The bolt rod is bent damage .

19． Design value of bearing capacity of single ordinary bolt

​

Add picture comments , No more than 140 word （ Optional ）

, In style

​

Add picture comments , No more than 140 word （ Optional ）

Express The smaller value of the total thickness of the pressure bearing member in the stress direction . 20． Ordinary bolt connection depends on Bolt rod Transfer shear ; Friction type high-strength bolt connection relies on The frictional force Transfer shear . 21. Manual welding Q235 steel , It is generally used E43 Type electrode . 22. The welded structure forms a heat affected zone near the weld , The material of this area There are defects . 23. The calculated length of side fillet weld connection or front fillet weld should not

​

Add picture comments , No more than 140 word （ Optional ）

. 24. Pressure bearing high-strength bolts are only used for Bear non dynamic loads Structure connection .

25. Adopt manual arc welding Q345 Steel shall be E50 Welding rod .

26． Conditions for equal stability of lattice axial compression members The slenderness ratio around the imaginary axis is the same as that around the real axis .

27． The buckling form of biaxially symmetric I-section axial compression members is bending buckling .

28. Axial compression member with uniaxial symmetric section , Occurs when the member loses stability around the axis of symmetry Twists and turns buckling .

29． The defects of axial compression members are Residual stress 、 Initial eccentricity 、 Initial curvature .

30． The buckling forms of axial compression members are Bending buckling 、 Torsional buckling 、 Bending, twisting and buckling .

31． Steel contains too much sulfur , It will happen under high temperature Hot crisp , Too much phosphorus , It will happen at low temperature Cold and crisp .

32． Age hardening will change the properties of steel , Will make the steel Strength Improve , plasticity 、 toughness Reduce .

33． Steel in 250ºC There are Strength Improve plasticity 、 toughness Reduce the phenomenon , Call it blue brittleness .

Two ． Short answer

1． Briefly describe what factors affect the properties of steel ？

Chemical composition ; Metallurgical defects ; Steel hardens ; The effect of temperature ; Stress concentration ; Repeated load action .

2． What are the mechanical performance indexes of steel for steel structure ？ At least which indexes of the steel of the load-bearing structure should meet the requirements ？

The mechanical performance indexes of steel are ： Tensile strength 、 Elongation 、 Yield point 、 Cold bending performance 、 Impact toughness ;

The steel of load-bearing structure should ensure the following three indicators are qualified ： Tensile strength 、 Elongation 、 Yield point .

3． What are the two damage phenomena and consequences of steel ？

Steel has brittle failure and plastic failure . Before plastic failure , The structure has obvious deformation , And has a long deformation duration , Easy to find and remedy . Brittle failure of steel , Due to small deformation and sudden damage , It's dangerous .

4． What is the basis for choosing the yield strength of steel as the standard value of static strength and regarding steel as an ideal elastic-plastic material ？

Choose yield strength fy As the standard value of static strength of steel, the basis is ：① It is the dividing point between elastic and plastic work of steel , And after steel yielding , The plasticity changes greatly （2%~3%）, It is very easy for people to notice , It can be handled in time , Avoid sudden damage ;② From yielding to fracture , The plastic working area is large , It is about larger than the elastic working area 200 times , It is the great backup strength of steel , And the ratio of tensile strength and yield strength is larger （Q235 Of fu/fy≈1.6~1.9）, These two points together endow the component with fy As a reliable safety reserve for strength limit .

Consider steel as ideal elasticity — The basis of plastic materials is ：① For the test piece without defects and residual stress , Comparing the limit and yield strength is relatively close （fp=(0.7~0.8)fy）, And because the strain of steel is small when it begins to yield （εy≈0.15%） Therefore, it is approximately considered that the steel is completely elastic before the yield point , Just before the yield point б-ε The figure is simplified as a slash ;② Because the steel flow range is quite long （ namely ε from 0.15% To 2%~3%）, The strength of the strengthening stage is not used in the calculation , Thus, after the yield point б-ε The figure is simplified to a horizontal line .

5． What is impact toughness ？ Under what circumstances is it necessary to ensure this indicator ？

​

Edit switch to center

Add picture comments , No more than 140 word （ Optional ）

6． Why is the strength of thin steel plate higher than that of thick steel plate ( Or the strength of steel is grouped according to its thickness or diameter )？

The rolling of steel can make the grain of metal bend fine , And eliminate the defects of microstructure , It can also make the pores formed during pouring , Cracks and looseness , Weld under high temperature and pressure . Therefore, after hot rolling , The steel structure is dense , The mechanical properties of steel are improved . The thin plate is rolled for many times , Its strength is slightly higher than that of thick plate .

7． What is the elongation index of the same steel δ5>δ10

If the original gauge length of the circular segment l0=10d0(d0 Is the diameter of the cylindrical specimen ), The resulting elongation is δ10; If the original gauge length of the cylindrical section l0=5d0, The resulting elongation is δ5. The absolute deformation value of the specimen when it breaks l There are two parts , One is the uniform elongation of the whole working section , The second is “ Necking ” Partial elongation of part ; Because the uniform elongation is related to the original gauge length , The local elongation is only related to the cross-sectional dimension of the original gauge length , therefore , Elongation δ The size of is related to the ratio of the original gauge length of the specimen to the cross-sectional size , therefore δ5≠δ10; And because local elongation accounts for a large proportion of deformation in the specimen with small original gauge length , so δ5>δ10.

8． For important welded structures under tension or bending , Tensile strength is required 、 Elongation 、 Yield strength and sulfur 、 phosphorus 、 Carbon content , Qualification guarantee of cold bending test , Why do we need a qualified guarantee with normal temperature impact toughness .

Important tensile or bending welded structures due to welding residual stress δr The existence of , There are often multidirectional tensile stress fields , Therefore, there is a greater risk of brittle failure . At the same time, for tension 、 Welded members in bending and compression （ Including bending ） The stress state of components is different , Result in different reaction speed to defects , Tension , The response speed of bending members is fast , High requirements for steel quality . Therefore, such components are required to have qualified assurance of impact toughness at room temperature .

9． Why should the minimum calculation length of fillet weld and the maximum calculation length of side fillet weld be specified ？

The weld leg size of fillet weld is large and the length is small , Local heating of weldments is serious , Defects caused by arc striking and extinguishing of weld are too close , And other defects that may occur in the weld ( Blowholes 、 Nonmetallic inclusions ), Make the weld unreliable , It specifies the minimum effective length of side fillet weld or front fillet weld .

The side fillet weld is under uneven stress along the length direction in the elastic stage , Big at both ends and small in the middle , Therefore, the maximum calculated length of side fillet weld is specified .

10． In which case does the butt weld need to be calculated ？

Welding defects on compression 、 The sheared butt weld has little effect , Therefore, it can be considered as under pressure 、 The strength of the sheared butt weld is equal to that of the base metal , But the tensile butt weld is very sensitive to defects . Due to a 、 The strength of the weld in the secondary inspection is equal to that of the base metal , Therefore, only the welds of level III Inspection need to be checked for tensile strength .

11． In shear connection , What is the difference between the working performance of ordinary bolt connection and friction type high-strength bolt connection ？

When ordinary bolts are sheared , There are four stages from stress to failure , Because it allows the contact surface to slide , The design criterion is that the connection reaches the limit state of failure ; When tightening high-strength bolts , There is a great pretension in the screw , And there is a lot of pre pressure between the connected plates . After the connection is stressed , Due to the friction generated on the contact surface , It can prevent the relative slip between plates under considerable load , Therefore, the flexible working stage is longer . When the external force exceeds the friction between plates , Relative sliding occurs between plates . Friction type connection with high strength bolts takes the sliding between plates as the ultimate state of shear capacity ,

12． How should bolts be arranged reasonably on the steel plate ？

The arrangement of bolts on the steel plate has two forms ： Juxtaposition and staggering . Side by side arrangement is compact , Neat and simple , The size of the connecting plate used is small , But the bolt weakens the section of the member greatly ; Staggered arrangement is loose , The connecting plate is larger , But it can reduce the weakening of the bolt hole to the section . The arrangement of bolts on the steel plate shall meet the requirements of three aspects ：① Stress requirements ② Construction requirements ③ Construction requirements , And it shall meet the maximum and minimum allowable distance specified in the specification ： The minimum bolt distance is 3d0, The minimum end distance is 2d0

13． What factors should be considered when selecting steel ？

The importance of structure 、 Load case 、 Connection method 、 Temperature and environment of the structure 、 Steel thickness

14． What factors are related to the stable bearing capacity of axial compression members ?

Geometry and size of components ; Rod end restraint ; Strength of steel ; Welding residual stress ; Initial bending ; Initial eccentricity

15． What are the failure forms of ordinary shear bolts ？ How to avoid these damages in the design （ Calculation method or construction method ）？

The forms of destruction are ： The bolt rod is cut ; The plate is crushed ; The plate is broken ; Plate punching and shearing failure ; Bending failure of bolt rod . The first three are calculated to avoid damage , The last two are constructed to avoid destruction .

16． What are the effects of welding residual stress on the structure ？

It has no effect on the static strength of the structure , Reduce the stiffness of the structure , Increase the brittle fracture tendency of steel at low temperature .

It has an obvious adverse effect on the fatigue strength of the structure .

17． Compared with the structure of other building materials , What are the characteristics of steel structure ？

（1） High strength of building steel , plasticity 、 Good toughness, light weight of steel structure （2） The weight of steel structure is light

（3） The material is even , It is more consistent with the assumption of mechanical calculation 4） The fabrication of steel structure is simple , The construction period is short （5） The steel structure has good airtightness （6） Poor corrosion resistance of steel structure （7） Steel is heat-resistant but not fire-resistant （8） Brittle fracture of steel structure under low temperature or other conditions

18． Why should the converted slenderness ratio be used in the stability design of lattice columns around the virtual axis ？

When the lattice axial compression column loses stability around the virtual axis , Shear force is mainly shared by batten , The shear deformation of the column is large , The additional deflection effect caused by shear cannot be ignored , Therefore, the instability calculation of the virtual axis , The influence of shear deformation is often considered by increasing the slenderness ratio , The increased slenderness ratio is called the converted slenderness ratio .

19． There are several types of high-strength bolt connections ？ What are the performance levels ？

There are two types of high-strength bolted connections ： Friction type connection and pressure bearing type connection . The performance grade of high-strength bolt is 8.8 Level and 10.9 level .

20． What are the guarantee conditions for the overall stability of the beam ？

（1） There are rigid planks closely laid on the compression flange of the beam and firmly connected with it , When it can prevent the lateral displacement of the compression flange of the beam ;

​

Edit switch to center

Add picture comments , No more than 140 word （ Optional ）

​

edit

Add picture comments , No more than 140 word （ Optional ）

29． What is called the loss of local stability of composite beams ？ How to avoid local instability ？

Composite beams are generally composed of plates such as flanges and webs , If these plates are improperly thinned and widened , When the medium pressure stress or shear stress of the plate reaches a certain value , The web or compression flange may deviate from its plane position , There is a wavy drum , This phenomenon is called beam local instability . The method of limiting the width thickness ratio is adopted to ensure the stability of the compressed flange plate of the beam , Adopt the method of setting stiffeners to ensure the local stability of the web .

30． The beam with load acting on the upper flange and the beam with load acting on the lower flange , What is the critical stress ？ Why? ？

When the load acts on the lateral torsion of the lower flange, the additional moment on the shear center will restrict the torsion of the beam ; When the load acts on the lateral torsion of the upper flange, the additional torque to the shear center will promote the torsion of the beam .

3、 ... and ． choice question

1、 The stress state most prone to brittle failure is B .

(A) Uniaxial compressive stress state

(B) Three dimensional tensile stress state

(C) Uniaxial tensile stress state

(D) The stress state of two-way tension and compression

​

edit

Add picture comments , No more than 140 word （ Optional ）

2、 Two pieces connected by friction type high-strength bolts The steel plate , As shown in the figure ,I－I The force on the dangerous section is B .

(A) N

(B) 0.875N

(C) 0.75N

(D) 0.5N

3、 As shown in the figure , Two steel plates are welded , According to the requirements of manual welding structure , Fillet height hf Should satisfy A requirement .

(A) 6≤hf≤8~9mm

(B) 6≤hf≤12mm

(C) 5≤hf≤8~9mm

​

edit

Add picture comments , No more than 140 word （ Optional ）

aaa

(D) 6≤hf≤10mm

4、 When considering the post buckling strength of flexural members , The following statement is correct B .

(A) The bending capacity of the web is improved

(B) The shear capacity of the web is improved

(C) Web bending 、 The shear bearing capacity is improved

(D) The bending capacity of the web is improved , The shear capacity decreases

​

Edit switch to center

Add picture comments , No more than 140 word （ Optional ）

A. The resistance moment of the wool section of the larger fiber under pressure B. The resistance moment of the wool section of the fiber under pressure

C. The net cross-sectional resistance moment of the larger compressed fiber D. The net cross-sectional resistance moment of the compressed smaller fiber

8． The width thickness ratio of the plate is increased , Its critical stress ( D ).

A Improve B Reduce C unchanged D The relationship is uncertain

9. When calculating the batten of lattice compression bending members , The shear force shall be taken as （ C ）.

A The design value of the actual shear force of the member B By formula

​

Add picture comments , No more than 140 word （ Optional ）

Calculated shear

C Whichever is greater D from

​

Add picture comments , No more than 140 word （ Optional ）

Calculated value

10. The allowable height thickness ratio of the web of I-section compression bending members is based on （ B ） affirmatory .

A It is between the height thickness ratio of axial compression bar web and beam web

B

​

Add picture comments , No more than 140 word （ Optional ）

Stress gradient with Web a0、 The relationship between the slenderness ratio of components

C Stress gradient of Web a0

D Slenderness ratio of components

​

Edit switch to center

Add picture comments , No more than 140 word （ Optional ）

A W1x and W2x It is the hair section resistance moment of the outermost fiber of the larger and smaller flange of the uniaxial symmetric section around the asymmetric axis ,gx Values are also different

B W1x and W2x Is the hair section resistance moment of the outermost fiber of the larger and smaller flange ,gx Values are also different

C W1x and W2x Is the hair section resistance moment of the outermost fiber of the larger and smaller flange ,gx Same value

D W1x and W2x It is the hair section resistance moment of the outermost fiber of the larger and smaller flange of the uniaxial symmetric section around the asymmetric axis ,gx Same value

​

Edit switch to center

Add picture comments , No more than 140 word （ Optional ）

13. A welded I-section simply supported beam , The materials are Q235,fy =235N/mm2 The beam is under uniformly distributed load , And support stiffeners have been set at the support , The web height and thickness of the beam are 900mm and 12mm, If web stability is considered , be （ B ）.

A Arrange longitudinal and transverse stiffeners B There is no need to arrange stiffeners

C Arrange stiffeners according to structural requirements D Arrange the transverse stiffeners according to the calculation

14. The worst overall stability of the following simply supported beams is （ A ）

A． Pure bending at both ends B． Full span uniformly distributed load

C． Mid span concentrated load action D． The concentrated load in the span acts at the third point

15. The transverse stiffener of the beam shall be set at （ C ）

A. The section with large bending stress B. The section with large shear stress

C. Where there is a large fixed and concentrated force D. Parts with crane wheel pressure

​

Edit switch to center

Add picture comments , No more than 140 word （ Optional ）

17. Biaxial symmetric section beam , Its strength just meets the requirements , However, the web may be partially unstable under bending stress , The following schemes are compared , Should use （ C ）.

A Set longitudinal 、 Transverse stiffeners B Set transverse stiffeners at the web of the beam

C Set longitudinal stiffeners at the web of the beam D Set transverse horizontal supports at the web along the length of the beam

18. When there is a fixed large concentrated load on the beam , Its action point should （ B ）.

A Set longitudinal stiffeners B Set transverse stiffeners

C Reduce web width D Increase the thickness of the flange

19. For local stability of steel beam webs （ D ） Rules .

A The local buckling stress of the web is equal to the overall buckling stress of the member

B The actual stress of the web does not exceed the buckling stress of the web

C The actual stress of the web is not less than the yield stress of the plate

D The local critical stress of the web is not less than the yield stress of the steel

20. The supporting stiffener of the beam shall be set at （ C ）

A． Section with large bending moment B． Section with large shear force

C． Parts with fixed concentrated load D． Parts with crane wheel pressure

Picture upload failed

​ retry

22． Lattice axial compression batten column composed of two channel steel , In order to improve the stable bearing capacity in the direction of the virtual axis （ D ）

A． Increase the strength of channel steel B． Increase the spacing of channel steel

C． Reduce the cross-sectional area of batten D． Increase the angle between the batten and the split limb

23． And the stability coefficient of axial compression members φ The relevant factors are （A ）

A． Section category 、 Steel grade 、 Slenderness ratio B． Section category 、 Calculate the length factor 、 Slenderness ratio

C． Section category 、 Two end connection structure 、 Slenderness ratio D． Section category 、 Length in both directions 、 Slenderness ratio

24． The factors that have nothing to do with the stable bearing capacity of the axial compression bar are （ A ）

A. Constraint condition of rod end B. Residual stress

C. Initial eccentricity of members D. Content of beneficial metal elements in steel

25． The loss of overall stability of axial compression members is caused by （ A ）

A． Caused by insufficient bearing capacity of individual sections B． Caused by insufficient stiffness of individual sections

C． Caused by insufficient bearing capacity of the whole member D． Caused by insufficient rigidity of the whole member

26. When the ratio of web height to thickness of I-section compression members cannot meet the requirements of calculation based on full web ,（ A ）.

A Only two edges of the web can be considered in the calculation

Picture upload failed

​ retry

Part of the cross-section takes part in bearing load

B The web must be thickened C Longitudinal stiffeners must be provided D Transverse stiffeners must be provided

27. Solid web axial compression rod winding x,y The slenderness ratio of the shaft is λx、λy , The corresponding stable coefficients are fx、fy , if λx=λy , be （ D ）.

A fx>fy Bfx=fy Cfx<fy D It needs to be classified and judged according to stability

28. Take stiffening measures to prevent the instability of plates in steel members , This practice is for （ D ）.

A Change the width thickness ratio of the plate B Increase the cross-sectional area

C Change the stress distribution on the section D Increase the moment of inertia of the section

Picture upload failed

​ retry

30． In order to ensure the stable bearing capacity of single limb of lattice member , Should be （ B ）.

A Control limb spacing B Control the section conversion slenderness ratio

C Control the slenderness ratio of single limb D Control the calculated length of components

31. Column base of axial compression column , The calculation basis of the thickness of the bottom plate is （C ）

A Work under pressure B Tensile work C Bending work D Shear work

32. Friction type high-strength bolt connection and pressure bearing type high-strength bolt connection （ C ）

A There is no essential difference B Different construction methods C The calculation methods of bearing capacity are different D Different materials

33. A steel plate bearing axial tension is connected with friction type high-strength bolts , The friction coefficient of the contact surface is 0.5,

The pretension in the bolt rod is 155KN, The shear surface of the bolt rod is a , The external tension acting on the steel plate

by 180KN, The number of bolts required for this connection is （ C ）

A. 1 individual B. 2 individual C. 3 individual D. 4 individual

34. The length of a side fillet weld is 600 mm, The welding leg is 8 mm, The calculated length of this weld should be which of the following （ B ）

A、600 mm B、584 mm C、496 mm D、480 mm

35. Which of the following belongs to the stress failure of bolted connections （ A ）

A、 The steel plate was cut B、 The bolt rod is bent C、 The bolt rod is pulled D、C Grade bolt connection slip

36. The thickness of two steel plates connected by a fillet weld is 8mm and 10mm, The proper weld leg size is （ B ）

A．4mm B．6mm C．10mm D．12mm

37. The weld leg size of a fillet weld is 8mm, The minimum length of this weld should be which of the following values （ A ）

A、40 mm B、64 mm C、80 mm D、90 mm

Picture upload failed

​ retry

C II Grade weld D A、B、C All right

39. Residual stress of hot rolled steel after cooling （ C ）.

A Mainly tensile stress B Mainly compressive stress

C Including pulling 、 Compressive stress D PULL 、 The compressive stress is very small

40. The main reason for longitudinal welding residual stress is （ D ）.

A The cooling rate is too fast B Each fiber of the weldment can deform freely C The elastic modulus of steel is too large , Make the member stiffness very large D Cold plastic and thermoplastic areas appear on the weldment during welding

41. The angle steel and steel plate are overlapped and connected by side welds , When the leg size and weld length of the leg back and limb tip weld of angle steel are equal at the same time ,（ C ）.

A The stress of the side weld on the back of the angle steel leg is equal to that on the tip of the angle steel leg

B The stress of the weld at the tip of the angle steel leg is greater than that at the back of the angle steel leg

C The stress of the side weld on the back of the angle steel leg is greater than that on the tip of the angle steel leg

D Because the stress of the side weld of the back and tip of the angle steel is not equal , Therefore, the connection is subjected to bending moment

42. For structures that directly bear dynamic loads , When calculating the front right angle weld （ C ）.

A Consider the improvement of the strength of the front fillet weld

B Consider the influence of weld stiffness

C The calculation formula is the same as that of side fillet weld

D take

Picture upload failed

​ retry

43． The following bolt damage belongs to structural damage （ B ）.

A The steel plate is damaged B The steel plate is sheared C The bolt is sheared D The bolt is broken

44． When bearing static load , The strength of front fillet weld is higher than that of side fillet weld （ A ）.

A high B low C equal D Unable to judge

​

Edit switch to center

Add picture comments , No more than 140 word （ Optional ）

Four ． Calculation questions

3、 As shown in the figure, a double leg channel steel lattice axial compression batten column , Design value of axial pressure N=1450kN（ Including the self weight of the column body and other structures ）, All steel materials are Q345,f=310N/mm2, Calculate the length l0x=6000mm ,l0y=3000mm, The column section is not weakened .

It is known that ：2[18b Cross sectional area of A=2×29.3=5860mm2,iy=68.4mm; The linear stiffness of the batten plate of the same section is greater than that of the larger column limb 6 I'm asking for it ; Split limbs to oneself 1-1 Moment of inertia of the shaft I1=1110000mm4, Radius of gyration i1=19.5mm;h=320mm,b =180mm,c=283.2mm; Other relevant parameters are shown in Figure .

Check the overall stability of the column （ Including limb stability ） Whether the requirements are met （ It is not necessary to carry out the checking calculation of batten ）.（12 branch ）

​

Edit switch to center

Add picture comments , No more than 140 word （ Optional ）

​

edit

Add picture comments , No more than 140 word （ Optional ）