07. Properties

7.1 Materials

7.1.1 Material List

QiaoTong software uses a docked list for centralized management of material creation. The list provides common operations such as Add, Modify, Delete, Compact Numbering, Delete All, and Copy.

• Commands:

  "Main Menu" > "Properties" > "Materials".

  From the tree menu, select "Work" > "Properties" > "Materials".

• Operations

  Add: Add a new material.

  Modify: Select the corresponding material in the list to edit or display that material.

  Delete: Select the corresponding material in the list to delete that material.

  Delete All: Delete all materials in the list.

  Compact Numbering: Renumber material IDs starting from 1.

  Copy: Select the material to be copied in the list and click Copy to duplicate it.

• Table Content

  Material ID: The serial number of the material.

  Material Name: User-defined material name.

  Values: Elastic modulus, Poisson's ratio, linear expansion coefficient, etc.

  Database: Includes basic data for four types of materials: concrete, steel, prestressed, and reinforcement.

7.1.2 New Material

• Function: Add material properties.

• Commands:

  "Main Menu" > "Properties" > "Materials" > "Add".

  From the tree menu, select "Work" > "Properties" > "Materials" > "Add Material".

• Input

  In the Material and Section dialog, enter the following data:

  Material ID: Define the material number

  Name: Define the material name

  Material Type: Select material type: Concrete, Steel, Prestressed, Reinforcement, or User-defined type.

  Code: Select the code.

  Construction Coefficient: During calculation, the material unit weight will be multiplied by this coefficient.

  Database: Select the material database.

  Values: Elastic modulus, Poisson's ratio, linear expansion coefficient, etc.

7.1.3 Shrinkage and Creep

• Function: Define shrinkage and creep.
• Command: "Main Menu" > "Properties" > "Materials" > "Shrinkage and Creep".

• Input

  In the Define Shrinkage and Creep dialog, enter the following data:

  • Name: Shrinkage and creep name

  • Code: Shrinkage and creep code

  • Basic Parameters:

    The creep basic coefficient $\varphi_{f1}$ and creep coefficient calculation parameter $\lambda$ in "Railway Code TB 10092-2017". Refer to Appendix 4 of "Highway Code JTJ 023-85" (see figure below).

    

  • Ultimate Shrinkage Strain:

    • Default is 0.00015, can be manually modified, or enter 0 to let QiaoTong software automatically calculate the ultimate shrinkage strain based on the structural theoretical thickness

7.1.4 Material Description

7.1.4.1 Concrete Materials

• Code ASTM
  • American Society for Testing and Materials (ASTM)
  • Includes concrete grades Grade2500-Grade15000, corresponding to design standard strength $f'c$ = 2500lbf ~ 15000lbf, i.e., $f'c$ = 2.5ksi ~ 15ksi.
  • Concrete unit weight is calculated according to Table 7.1.
  • Concrete elastic modulus calculation method:
    • For normal concrete with unit weight $w_{c}=0.145$ kcf and design compressive strength not exceeding 10.0 ksi, $E_{c}$ is calculated according to Equation 7.1: $$E_{c}=33,000 K_{1} {w_{c}}^{1.5} \sqrt{f_{c}^{\prime}\,} \tag{7.1}$$
    • For normal concrete with design compressive strength exceeding 10.0 ksi but not greater than 15.0 ksi, $E_{c}$ is calculated according to Equation 7.2: $$E_{c}=120,000 K_{1} {w_{c}}^{2.0} {f_{c}^{\prime}}^{0.33} \tag{7.2}$$
• Code AASHTO 17/20/24
  • AASHTO LRFD Bridge Design 2017/2020/2024 versions (The American Association of State Highway and Transportation Officials)
  • Includes concrete grades Grade2500-Grade15000, corresponding to design standard strength $f'c$ = 2500lbf ~ 15000lbf, i.e., $f'c$ = 2.5ksi ~ 15ksi.
  • Concrete unit weight is calculated according to Table 7.1.
  • Concrete elastic modulus calculation method:
    • For normal concrete with design compressive strength not greater than 15.0 ksi, $E_{c}$ is calculated according to Equation 7.3: $$E_{c}=120,000 K_{1} {w_{c}}^{2.0} {f_{c}^{\prime}}^{0.33} \tag{7.3}$$

Table 7.1 Unit Weight

Material	Unit Weight (kcf)/Unit Length Weight (klf)
Concrete
Lightweight concrete	0.110~0.135
Normal concrete ($f'c$ ≤5.0 ksi)	0.145
Normal concrete (5.0< $f'c$ ≤15.0 ksi)	0.140+0.001 $f'c$

7.2 Sections

7.2.1 Section List

• Commands:

"Main Menu" > "Properties" > "Sections".

From the tree menu, select "Work" > "Properties" > "Sections".

• Operations

  Add: Add a new section.

  Modify: Select the corresponding section in the list to edit or display that section.

  Delete: Select the corresponding section in the list to delete that section.

  Delete All: Delete all sections in the list.

  Compact Numbering: Renumber section IDs starting from 1.

  Copy: Select the section to be copied in the list and click Copy to duplicate it.

  Export Dxf: Export the section as a Dxf file.

• Table

  • Section table properties are defined as follows:

    Column Header	Property
    Section ID	Section number
    Name	Section name
    Area	Section area
    Ix	Torsional moment of inertia about element local x-axis
    Iy	Moment of inertia about element local y-axis
    Iz	Moment of inertia about element local z-axis
    z1, y1	z, y coordinates of corner point 1.
    z2, y2	z, y coordinates of corner point 2.
    Z3, y3	z, y coordinates of corner point 3.
    Z4, y4	z, y coordinates of corner point 4.

  • Section types are divided into:

    Parametric Section

    Custom Section

    Property Section

    Composite Section

    Composite Beam Section

    Tapered Section

7.2.2 Parametric Section

• Function: Define parametric sections.

• Commands:

  From the main menu, select "Properties" > "Sections" > "Add Section" > "General Section" > "Parametric Section".

  From the tree menu, select "Work" > "Sections" > "Add Section" > "General Section" > "Parametric Section".

• Input

  • Section Type

    Select the desired section type. Parametric sections include 16 types.

    

    See 4.6.2.1 Basic Section Types, 4.6.2.2 Concrete Section Types, 4.6.2.3 Steel Beam Section Types.

  • Section ID

    The new section ID is automatically set to current maximum section ID + 1.

  • Name

    Enter the section name.

  • Geometric Information

    Enter section geometric information.

  • Eccentricity

    Display the current section eccentricity. There are 10 alignment methods: Center, Top Center, Bottom Center, Left Center, Right Center, Top Left, Top Right, Bottom Left, Bottom Right, and User-defined. If User-defined is selected, custom eccentricity coordinates need to be entered.

  • Consider Shear Deformation

    Select whether to consider shear deformation.

  • Mesh Density

    Enter mesh density

  • View Section Properties

    

    

    • A: Cross-sectional area.
      • Basic geometric and position properties
        • Ax: Cross-sectional area (A).
        • Ay: Effective shear area in the element local y-axis direction.
          • When shear deformation is not considered, this property value has no effect.
        • Az: Effective shear area in the element local z-axis direction.
          • When shear deformation is not considered, this property value has no effect.
        • Peri:O: Outer perimeter of the section.
        • Peri:I: Inner perimeter of box or tubular sections.
      • Bending and torsional properties
        • Ix: Torsional moment of inertia about element local x-axis.
        • Iy: Moment of inertia about element local y-axis.
        • Iz: Moment of inertia about element local z-axis.
        • Iyz: Product of inertia in the element local yz-plane.
        • Iw: Warping constant
        • Thw: Web thickness. (Web thickness is used for calculating oblique section shear capacity, shear stress, and principal stress; can be filled as 0 if these items are not checked)
        • Tt: Top slab thickness. (Affects calculation under railway top slab temperature mode; can be filled as 0 if not considered)
        • Cyp: Distance from the neutral axis to the edge fiber along the element local +y-axis direction.
        • Cym: Distance from the neutral axis to the edge fiber along the element local -y-axis direction.
        • Czp: Distance from the neutral axis to the edge fiber along the element local +z-axis direction.
        • Czm: Distance from the neutral axis to the edge fiber along the element local -z-axis direction.
        • Qyb: Shear coefficient along the element local z-axis direction.
        • Qzb: Shear coefficient along the element local y-axis direction.
        • Cent:y: Distance from the leftmost point of the section to the centroid.
        • Cent:z: Distance from the bottommost point of the section to the centroid.
      • Shear properties
        • Shear Center Y: Horizontal distance from shear center to centroid
        • Shear Center Z: Vertical distance from shear center to centroid
        • y1, z1: y, z coordinates of the top-leftmost edge point of the section.
        • y2, z2: y, z coordinates of the top-rightmost edge point of the section.
        • y3, z3: y, z coordinates of the bottom-rightmost edge point of the section.
        • y4, z4: y, z coordinates of the bottom-leftmost edge point of the section.
        • Equivalent Thickness Hys: Equivalent thickness for calculating shear stress along the y-axis direction.
        • Equivalent Thickness Hzs: Equivalent thickness for calculating shear stress along the z-axis direction.
        • Maximum Static Moment about y-axis Sys: Moment of half the section area about the neutral axis, i.e., static moment or area moment (S).
        • Maximum Static Moment about z-axis Szs: Moment of half the section area about the neutral axis, i.e., static moment or area moment (S).

7.2.2.1 Basic Section Types

QiaoTong's built-in basic section types include:

Rectangle, Circle, Circular Tube, Box, Solid Octagon, Hollow Octagon, Inner Octagon, Solid Round-End, Hollow Round-End, Inverted T-shape, T-shape, I-shape.

(1) Rectangle

Parameter	Remarks
W	Length
H	Height

(2) Circle

Parameter	Remarks
D	Diameter

(3) Circular Tube

Parameter	Remarks
D	Diameter
t	Wall thickness

(4) Box

Parameter	Remarks
W	Length
H	Height
dw	Bottom slab width
tw	Web thickness
tt	Top slab thickness
tb	Bottom slab thickness

(5) Solid Octagon

Parameter	Remarks
W	Length
H	Height
a	Chamfer height
b	Chamfer width

(6) Hollow Octagon

Parameter	Remarks
W	Length
H	Height
tw	Web thickness
tt	Top slab thickness
tb	Bottom slab thickness
a	Chamfer width
b	Chamfer height

(7) Inner Octagon

Parameter	Remarks
W	Length
H	Height
tw	Web thickness
tt	Top slab thickness
tb	Bottom slab thickness
a	Chamfer width
b	Chamfer height

(8) Solid Round-End

Parameter	Remarks
W	Length
H	Height

(9) Hollow Round-End

Parameter	Remarks
W	Length
H	Height
t	Wall thickness

(10) T-shape

Parameter	Remarks
W	Length
H	Height
tw	Web thickness
tt	Top slab thickness

(11) Inverted T-shape

Parameter	Remarks
W	Length
H	Height
tw	Web thickness
tt	Bottom slab thickness

(12) I-shape

Parameter	Remarks
Wt	Top slab width
Wb	Bottom slab width
H	Height
tw	Web thickness
tt	Top slab thickness
tb	Bottom slab thickness

7.2.2.2 Concrete Section Types

QiaoTong's built-in concrete section types include:

Horseshoe T-shape, I-shaped Concrete, Concrete Box Beam.

(1) Horseshoe T-shape

Parameter	Remarks
W	Length
H	Height
tw	Web thickness
tt	Bottom slab thickness
tb	Web bottom variable height
a1	Top slab chamfer width
b1	Top slab chamfer height
a2	Web chamfer width
b2	Web chamfer height

(2) I-shaped Concrete

Parameter	Remarks
Wt	Top slab width
Wb	Bottom slab width
H	Height
tw	Web thickness
tt	Top slab thickness
tb	Bottom slab thickness
a1	Top slab chamfer width
b1	Top slab chamfer height
a2	Bottom slab chamfer width
b2	Bottom slab chamfer height

(3) Concrete Box Beam

Parameter	Remarks
B	Total bridge deck width
N	Number of box cells
H	Beam height
Symmetric
Left Box Data
i1	Top slab slope
i2	Bottom slab slope
B0	Top slab width
B1	Cantilever width
B1a	Cantilever width
B1b	Cantilever width
B2	Left web horizontal projection
B3	Edge cell bottom width
B4	Middle cell bottom width
H1	Cantilever end height
H2	Cantilever bottom edge height
H2a	Cantilever bottom edge height
H2b	Cantilever bottom edge height
T1	Top slab thickness
T2	Bottom slab thickness
T3	Edge web thickness
T4	Middle web thickness
R1	Cantilever root chamfer
R2	Edge web external bottom chamfer
C1	Edge web top chamfer
C2	Edge web bottom chamfer
C3	Middle web top chamfer
C4	Middle web bottom chamfer
Right Box Data
i1r	Top slab slope
i2r	Bottom slab slope
B0r	Top slab width
B1r	Cantilever width
B1ar	Cantilever width
B1br	Cantilever width
B2r	Left web horizontal projection
B3r	Edge cell bottom width
B4r	Middle cell bottom width
H1r	Cantilever end height
H2r	Cantilever bottom edge height
H2ar	Cantilever bottom edge height
H2br	Cantilever bottom edge height
T1r	Top slab thickness
T2r	Bottom slab thickness
T3r	Edge web thickness
T4r	Middle web thickness
R1r	Cantilever root chamfer
R2r	Edge web external bottom chamfer
C1r	Edge web top chamfer
C2r	Edge web bottom chamfer
C3r	Middle web top chamfer
C4r	Middle web bottom chamfer

📌For multi-cell box beams, middle cell bottom width (B4), middle web thickness (T4), top slab width (B0), and top slab slope (i1) can have multiple values separated by "|". When middle cell bottom width (B4) and middle web thickness (T4) are separated by "|", the parameter size is controlled from both sides of the box beam towards the center. When top slab width (B0) and top slab slope (i1) are separated by "|", the parameter size is controlled from the center of the box beam towards both sides. The number of top slab widths must equal the number of top slab slopes.

7.2.2.3 Steel Beam Section Types

QiaoTong's built-in concrete section types include:

Ribbed Steel Box, Ribbed H-section, Steel Truss Box Beam 1, Steel Truss Box Beam 2, Steel Truss Box Beam 3, Ribbed Steel I-section.

(1) Ribbed Steel Box

Parameter	Remarks
W	Length
H	Height
tw	Web thickness
tt	Top slab thickness
tb	Bottom slab thickness
hrt	Top/bottom slab rib height
trt	Top/bottom slab rib thickness
hrw	Web rib height
trw	Web rib thickness
dh	Top/bottom slab rib spacing
dv	Web rib spacing
Nh	Number of web ribs
Nv	Number of top/bottom slab ribs

(2) Ribbed H-section

Parameter	Remarks
H	Height
B	Length
tw	Left/right web thickness
tt	Transverse web thickness
h1	Web rib height
t	Web rib thickness

(3) Steel Truss Box Beam 1

Parameter	Remarks
H	Height (excluding top and bottom slab cantilevers)
B	Length
W2	Left cantilever length
W3	Right cantilever length
h0	Bottom cantilever height
Tw	Web thickness
Tt	Top slab thickness
Tb	Bottom slab thickness
h1	Top slab rib height
t	Top slab rib thickness
h1	Bottom slab rib height
t	Bottom slab rib thickness
d1	Top slab to web rib spacing
n	Number of web ribs
d	Web rib spacing
h1	Web rib height
t	Web rib thickness
Left web rib position d	Inner/Outer
Right web rib position d	Inner/Outer
d2	Left cantilever rib spacing
h1	Left cantilever rib height
t	Left cantilever rib thickness
b1	Left cantilever rib top distance
b2	Left cantilever rib bottom distance
r	Left cantilever rib chamfer
d3	Right cantilever rib spacing
h1	Right cantilever rib height
t	Right cantilever rib thickness
b1	Right cantilever rib top distance
b2	Right cantilever rib bottom distance
r	Right cantilever rib chamfer
Top/bottom slab rib count	--
Top/bottom slab rib spacing	--

(4) Steel Truss Box Beam 2

Parameter	Remarks
H	Height
B	Length
w2	Left top cantilever length
w3	Right top cantilever length
w4	Left bottom cantilever length
w5	Right bottom cantilever length
tw	Web thickness
tt	Top slab thickness
tb	Bottom slab thickness
h1	Top slab rib height
t	Top slab rib thickness
h1	Bottom slab rib height
t	Bottom slab rib thickness
d1	Distance between top slab and web ribs
n	Number of web ribs
d	Web spacing
h1	Web rib height
t	Web rib thickness
Left web rib position	Inner/Outer
Right web rib position	Inner/Outer
d2	Left top cantilever rib spacing
h1	Left top cantilever rib height
t	Left top cantilever rib thickness
b1	Left top cantilever rib top distance
b2	Left top cantilever rib bottom distance
r	Left top cantilever rib chamfer
d3	Right top cantilever rib spacing
h1	Right top cantilever rib height
t	Right top cantilever rib thickness
b1	Right top cantilever rib top distance
b2	Right top cantilever rib bottom distance
r	Right top cantilever rib chamfer
d4	Left bottom cantilever rib spacing
h1	Left bottom cantilever rib height
t	Left bottom cantilever rib thickness
d5	Right bottom cantilever rib spacing
h1	Right bottom cantilever rib height
t	Right bottom cantilever rib thickness
Top/bottom slab rib count	--
Top/bottom slab rib spacing	--

(5) Steel Truss Box Beam 3

Parameter	Remarks
H	Height
B	Length
d0	Top cantilever rib height
d1	Bottom cantilever rib height
tw	Web thickness
tt	Top slab thickness
tb	Bottom slab thickness
h1	Top slab rib height
t	Top slab rib thickness
h1	Bottom slab rib height
t	Bottom slab rib thickness
h1	Web rib height
t	Web rib thickness

(6) Ribbed Steel I-section

Parameter	Remarks
Ht	Top slab length
Hb	Bottom slab length
B	Middle web height
Tt	Top slab thickness
Tb	Bottom slab thickness
Tw	Web thickness
D1	Distance between top slab and web ribs
n	Number of ribs
d	Rib spacing
h1	Rib height
t	Rib thickness

7.2.3 Custom Section

• Function: Define custom sections.

• Commands:

  From the main menu, select "Properties" > "Sections" > "Add Section" > "General Section" > "Custom Section".

  From the tree menu, select "Work" > "Sections" > "Add Section" > "General Section" > "Custom Section".

• Input

  • Section Type

    Line loop

    Line width

  • Section ID

    The new section ID is automatically set to current maximum section ID + 1.

  • Name

    Enter the section name.

  • Batch Generation

    Batch generate multiple identical sections.

  • Eccentricity

    Display the current section eccentricity. There are 10 alignment methods: Center, Top Center, Bottom Center, Left Center, Right Center, Top Left, Top Right, Bottom Left, Bottom Right, and User-defined. If User-defined is selected, custom eccentricity coordinates need to be entered.

  • Consider Shear Deformation

    Select whether to consider shear deformation.

  • Mesh Density

    Enter mesh density

  • View Section Properties

7.2.4 Property Section

• Function: Define custom sections.

• Commands:

  From the main menu, select "Properties" > "Sections" > "Add Section" > "General Section" > "Custom Section".

  From the tree menu, select "Work" > "Sections" > "Add Section" > "General Section" > "Custom Section".

• Input

  • Section ID

    The new section ID is automatically set to current maximum section ID + 1.

  • Name

    Enter the section name.

  • Section Properties

    Enter section property values.

  • Eccentricity

    Display the current section eccentricity. There are 10 alignment methods: Center, Top Center, Bottom Center, Left Center, Right Center, Top Left, Top Right, Bottom Left, Bottom Right, and User-defined. If User-defined is selected, custom eccentricity coordinates need to be entered.

  • Consider Shear Deformation

    Select whether to consider shear deformation.

7.2.5 Composite Section

• Function: Define composite sections.

• Commands:

  From the main menu, select "Properties" > "Sections" > "Add Section" > "Composite Section".

  From the tree menu, select "Work" > "Sections" > "Add Section" > "Composite Section".

• Operations

  • Section Type

    Steel pipe concrete

  • Section ID

    The new section ID is automatically set to current maximum section ID + 1.

  • Name

    Enter the section name.

  • Geometry

    Enter section geometric parameters.

  • Material

    Enter section material coefficients: elastic modulus ratio, unit weight ratio, Poisson's ratio, expansion coefficient. Or select materials from the database.

    • Es/Ec: Ratio of steel to concrete elastic modulus
    • Ds/Dc: Ratio of steel to concrete unit weight.
    • Ps: Steel beam Poisson's ratio
    • Pc: Concrete Poisson's ratio
    • Ts/Tc: Ratio of steel to concrete thermal expansion coefficient

  • Eccentricity

    Display the current section eccentricity. There are 10 alignment methods: Center, Top Center, Bottom Center, Left Center, Right Center, Top Left, Top Right, Bottom Left, Bottom Right, and User-defined. If User-defined is selected, custom eccentricity coordinates need to be entered.

  • Consider Shear Deformation

    Select whether to consider shear deformation.

  • View Section Properties

    📌The CentY and CentZ values in the main/auxiliary section properties of a composite section represent the offset of the centroid of the combined section. The CentY and CentZ values of the composite section represent the offset of the centroid from the bottom-left corner of the section bounding box.

• Composite Section Types

7.2.5.1 Composite Section Types

There are currently two types in the software: steel pipe concrete and steel box concrete.

(1) Steel Pipe Concrete

Parameter	Remarks
D	Steel pipe diameter
t	Steel pipe wall thickness

(2) Steel Box Concrete

Parameter	Remarks
W	Length
H	Height
dw	Steel box bottom slab width
tw	Steel box web thickness
tt	Steel box top slab thickness
tb	Steel box bottom slab thickness

7.2.6 Composite Beam Section

• Function: Define composite beam sections.

• Commands:

  From the main menu, select "Properties" > "Sections" > "Add Section" > "Composite Beam Section".

  From the tree menu, select "Work" > "Sections" > "Add Section" > "Composite Beam Section".

• Operations

  • Section Type

    I-shaped composite beam

    Box-shaped composite beam

    Custom composite beam

  • Section ID

    The new section ID is automatically set to current maximum section ID + 1.

  • Name

    Enter the section name.

  • Geometry

    Enter section geometric parameters.

  • Material

    Enter section material coefficients: elastic modulus ratio, unit weight ratio, Poisson's ratio, expansion coefficient. Or select materials from the database.

    • Es/Ec: Ratio of steel to concrete elastic modulus
    • Ds/Dc: Ratio of steel to concrete unit weight.
    • Ps: Steel beam Poisson's ratio
    • Pc: Concrete Poisson's ratio
    • Ts/Tc: Ratio of steel to concrete thermal expansion coefficient

  • Eccentricity

    Display the current section eccentricity. There are 10 alignment methods: Center, Top Center, Bottom Center, Left Center, Right Center, Top Left, Top Right, Bottom Left, Bottom Right, and User-defined. If User-defined is selected, custom eccentricity coordinates need to be entered.

  • Consider Shear Deformation

    Select whether to consider shear deformation.

  • View Section Properties

    📌The CentY and CentZ values in the main/auxiliary section properties of a composite beam section represent the offset of the centroid of the combined section. The CentY and CentZ values of the composite beam section represent the offset of the centroid from the bottom-left corner of the section bounding box.

  • Custom Composite Beam Section

    Enter the number of blocks, draw the main material and auxiliary material parts in the graphic view, then click

    

    Define geometry and materials for the main and auxiliary materials. After clicking, select line segments in the drawing window with the left mouse button, then right-click to complete the selection.

    

7.2.6.1 Composite Beam Section Types

There are currently two types in the software: I-shaped composite beam and steel box concrete.

(1) I-shaped Composite Beam

Parameter	Remarks
Wc	Auxiliary material length
Hc	Auxiliary material height
Wt	Main material top slab width
Wb	Main material bottom slab width
H	Main material height
tw	Main material web thickness
tt	Main material top slab thickness
tb	Main material bottom slab thickness

(2) Steel Box Concrete

Parameter	Remarks
Wc	Auxiliary material length
Hc	Auxiliary material height
W	Main material length
dw	Main material bottom slab width
H	Main material height
tw	Main material web thickness
tt	Main material top slab thickness
tb	Main material bottom slab thickness

7.2.7 Tapered Section

• Commands:

  "Main Menu" > "Properties" > "Sections" > "Tapered Section".

  From the tree menu, select "Work" > "Properties" > "Sections" > "Tapered Section".

• Operations

  • Section ID

    The new section ID is automatically set to current maximum section ID + 1.

  • Name

    Enter the section name.

  • Section Type

    Parametric Section

    Custom Section

  • Section Shape

    Enter section geometric shape. If it's a custom section, select line loop or line width section.

  • Variation Coefficient Value

    When the variation coefficient = 1, it represents linear variation along the element local x-axis direction; when the variation coefficient = 2, it represents parabolic variation along the element local x-axis direction.

    Taking a rectangular beam section as an example, if the height H varies according to a 1.8-degree parabola $H=Ax^{1.8}+Bx+C$, and the section width L remains constant, the weak axis moment of inertia H\times$$L^{3}/12 will also vary according to a 1.8-degree parabola.

  • Consider Shear Deformation

    Select whether to consider shear deformation.

  • Auto Sort

    Select whether to automatically sort. Auto-sorting defaults to using the longest line segment at the I-end as the first segment. The corresponding J-end first segment defaults to the segment closest to the I-end (and with the same width as the I-end first segment). Users can determine the sorting rule by changing the width of the longest line segment at the I-end and the width of the corresponding segment at the J-end (adding 0.1mm does not affect section properties), thereby ensuring that the first segments correspond when sorting at the I-end and J-end.

7.2.7 Tapered Section Group

• Function: Group elements with the same tapered section. The I and J ends of the original tapered section become the I and J ends of the tapered section group, and the software automatically calculates the section property values of elements within the tapered section group.
• Command: From the main menu, select "Properties" > "Tapered Section Group".

• Operations

  • Selected Elements

    Select in the model window.

  • Name

    Enter the section group name.

  • Width Y, Height Z

    • Linear: Linear variation.

    • Nonlinear: Curve variation according to the number filled on the right. Example: enter 2 for quadratic curve variation.

    • Symmetry Plane:

      The position where the tangent of the section variation curve is parallel to the element coordinate system x-axis can be represented by the distance from the reference point.

      • Reference Point: Select whether the reference point is the I-end or J-end.
      • Distance: The distance along the element coordinate system x-axis from the reference point to the symmetry plane.

      🧐Note: If you need to define a nonlinear curve, three non-collinear known points are required. The symmetry plane position is the third point position of the nonlinear curve (I and J ends are known).

  • Add

    Add a new tapered section group.

  • Edit

    Edit the tapered section selected in the tapered section group list.

  • Delete

    Delete the tapered section group.

  • Convert to Tapered Section

    The software will generate new tapered sections based on the number of elements in the tapered section group and the interpolated section property values calculated by the software for the tapered section group. After the tapered section group is converted to a tapered section, the tapered section group information will be automatically deleted.

7.2.7 Parametric Tapered Section Group

• Function: QiaoTong supports the function of forming parametric tapered section groups for parametric section types (custom line loop sections and custom line width sections are not yet supported). Users can modify the parameter dimensions of sections within the tapered section group according to linear or nonlinear laws.
• Command: From the main menu, select "Properties" > "Parametric Tapered Section Group".

To generate a parametric tapered section group, follow the process below:

• Select group elements

  Select elements to be included in the tapered section group according to design requirements. Note: All elements within the tapered section group must be the same tapered section. After selecting elements, the Section Type in the left operation panel will automatically identify the current tapered section type. If the section type is empty, parametric tapered section groups cannot be added for this type of section.

  

• Select parameters to change dimensions based on element section

  

  Select "Add" at "Define Parameters" to open the "Define Parameter Variation Trend" panel. Select the parameters that need to change dimensions. The parameter names will be automatically determined based on the current tapered section's dimensional parameters.

  

  There are two ways to define the variation trend of parameter values: Nonlinear and Custom.

  Nonlinear: Parameters show a nonlinear variation trend. For example, in this case, the beam height needs to show a quadratic variation trend from the support point to the zero block, so enter 2 for the exponent, enter I-end for the reference point, and enter 0 for the distance.

  

  Custom: Parameters show a linear variation trend. For example, in this case, the edge web thickness T3 changes from 13.05m at the starting I-end of the tapered section group to 0.48m thickness, then to 0.7m thickness after 3m. Fill in the variation trend according to the table in the figure.

  

• Click Add

  

  After completing the parameter definition, you can add a tapered section group. Four parametric tapered section groups have been added in the figure.

  Note: If the section dimensions of a certain parametric tapered section group need to change, select that group in the list. The software will automatically select the related elements and display their group parameters. After editing the parameters in "Define Parameters" according to requirements, click "Edit" to complete the editing of the parametric tapered section group.

7.2.7 Query Section

• Function: Query section information.
• Command: From the main menu, select "Properties" > "Query Section".

Click on the element to be queried in the model view to quickly view the section preview of the selected element. If it's a tapered section, the preview window will display the I (left) and J (right) end section previews, and the text area will display basic section information.

7.3 Plate Thickness

In QiaoTong, there are two ways to define plate element thickness: normal plate thickness and stiffened plate thickness.

7.3.1 Normal Plate Thickness

When plate elements use normal plate thickness, the plate element is a normal plate.

7.3.2 Stiffened Plate Thickness

When plate elements use stiffened plate thickness, the plate element is an orthotropic plate element. The plate element has stiffeners in both transverse and longitudinal sections. Currently, U-shaped stiffeners and T-shaped stiffeners are provided.

For the torsional stiffness Ix of U-shaped stiffeners, the torsional stiffness of thin-walled closed tubular sections is used for correction with the formula:

$$I_{x}=\frac{4 A^{2}}{\oint d_{s} / t}$$

Where A is the area of the closed tubular section, $\oint d_{s}$ is the perimeter of the centerline of the thin-walled section, and t is the thickness.

When converting to the calculation model, plate elements with stiffened plate thickness will undergo the following transformation:

(1) Orthotropic plate elements consist of normal plate elements and equivalent beam elements;

(2) Number of stiffeners $N$, where $length$ is the side length of the plate element and $space$ is the stiffener spacing:

$$N=\frac{\text { length }}{\text { space }} \text{(rounded down)}$$

(3) Single stiffener section properties are $A_{0 x}, \quad I_{0 x}, \quad I_{0 y}, \quad I_{0 z}, \quad Cent Y, \quad CentZ$

(4) Beam element section equivalence:

$$\begin{array}{c}\\A_{x}=\left(N \times A_{0 x}\right) / 2 \\\\I_{x}=\left(N \times I_{0 x}\right) / 2 \\\\I_{y}=\left(N \times I_{0 y}\right) / 2 \\\\I_{z}=\sum_{i}^{N}\left(I_{0 z}+A_{0 z} \times d_{i}^{2}\right) / 2\\\\\text{Section eccentricity} (CentY, CentZ)\\\end{array}$$

Where $d_i$ is the horizontal distance from the $i$-th stiffener to the plate center position.

7.3.3 Thickness Table

In the thickness table, you can modify the ID, name, and thickness information of already added thicknesses. You can also batch add thickness information through table paste operations.