Type of Space Frame structure

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- The Three Gorges Project is a magnificent project

spanning the century. Its warehouse has a total

length of 642.7m and a width of 39.0m. There are

two 1200T bridge cranes and two 125T small bridge

cranes in the workshop. The roof load is

relatively large. The roof adopts a square cone

welded ball space frame. The frame structure and

the space frame structure are supported on the

upstream and downstream wall structures. The

space frame structure participates in the overall

function of the warehouse structure, and the load

combination is very complicated.

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? . The form and selection of space frame

- 1. The characteristics of the space frame
- 2. The form of the space frame structure
- 3. Selection of space frame structure

1. The characteristics of the space frame

- The space frame structure is a spatial dumpling

connecting rod structure, which is a spatial

high-order statically indeterminate structure

system with good mechanical performance. - advantage
- Space structure, less steel consumption,

economical - Wide application range and strong

adaptability - The overall rigidity is large, the stability

is good, the shock resistance is good, and the

safety reserve is high - Flexible shape, convenient layout, beautiful

and lightweight - Industrial production

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2. The form of the space frame structure

- 1. The space frame structure is divided into

double-layer space frame and multi-layer

(three-layer) space frame according to the number

of layers. - 2. The double-layer space frame is composed of

the upper mystical layer, the abdominal poles,

and the lower mystical layer. - 3. The three-layer space frame is composed of

upper, middle, lower, upper and lower abdomen

layers.

Double-layer space frame form

- 1. Plane quilting system 1 Two-way orthogonal

placement 2. Two-way orthogonal oblique placement

3. Two-way oblique intersecting oblique placement

4. Three-way space frame - 2. Quadrangular pyramid system 1. Positive

quadrangular pyramid system 2. Positive discharge

quadrangular pyramid system 3. Unidirectional

polyline space frame 4. Oblique quadrangular

pyramid system 5. Checkerboard quadrangular

pyramid space frame 6. Star quadrangular pyramid - 3. Triangular cone system 1. Triangular cone

space frame - 2. Evacuate triangular cone space frame 3.

Honeycomb triangular cone space frame

(1), two-way orthogonal positive-laying space

frame

- The two-direction orthogonal right-laying is

formed by the vertical crossing of two-direction

plane trusses. When applied in a rectangular

building plan, the two-way quilting is

perpendicular to the boundary (parallel) - The number of space frame in the two

directions should be arranged in an even number.

If it is an odd number, the internodes in the

middle of the quilt should be made into cross

webs. - Because the space frame composed of the

upper and lower chords of the space frame is

rectangular, the webs are in the plane of the

upper and lower chords, which is geometrically

variable.

- The force of the two-way orthogonal

orthographic space frame is similar to the

two-way equal-rigidity cross beam, which varies

with the plane size and supporting conditions.

For peripheral support, the closer the plane size

is to the square, the closer the internal forces

of the quilting rods in the two directions, and

the more significant the spatial effect. But with

the increase of the side length ratio, the

one-way force transmission effect increases

obviously. For the point-supported space frame,

the internal force of the rod near the support

and the rod of the main quilt is larger, and the

internal force of the rods in other parts is

small, and the difference between the two is

large.

- Two-way Orthogonal Space Frame

(2) Two-way orthogonal diagonally placed space

frame

- The two-way orthogonal diagonal space frame is

formed by the vertical cross of the two-way flat

quilting frame. When applied in the rectangular

building plan, the angle between the two-way

frame and the boundary is 45 degrees. It can be

understood as a two-way orthogonal orthographic

space frame that rotates at an angle of 45

degrees when it is placed on the building plane.

The span of the two directions of the two-way

orthogonal diagonal space frame frame is

different, the number of nodes is more or less,

and the short bracket near the corner is more

rigid, and it supports the long quilt

perpendicular to it. Reducing the force on the

mid-span chord of the long quilted frame is

beneficial to the force on the space frame frame.

Two-way orthogonal diagonally placed space frame

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Two synchro diagonally placed space frame

Three-way space frame

(4) Three-way space frame

- The three-way space frame is composed of three

quilting frames intersecting each other at an

angle of 60 degrees. The space frames of the

upper and lower chord planes of this type of

space frame are regular triangles, which are

geometrically invariant, with large spatial

rigidity, good force performance, and the support

force is relatively uniform, but the members that

meet at a node can reach as many as 13 The root

and node structure is more complicated, and

welded hollow sphere nodes should be used.

Three-way space frames are suitable for larger

spans (greater than 60 meters), and the building

planes are triangles, hexagons, polygons and

circles. When used for circular planes, some

non-triangular space frames will appear around

them.

(5), forward quadrangular pyramid system

Basic unit of quadrangular pyramid system

Square pyramid space frame

- The quadrangular pyramid space frame frame is

composed of inverted quadrangular pyramids, the

four sides of the cone bottom are the upper

chords of the space frame, the cone edges are the

webs, and the tops of the cones are connected to

form the lower chord. When the building plane is

rectangular, the upper and lower chords are

parallel (perpendicular) to the boundary. The

upper and lower nodes are respectively connected

with 8 rods, and the node structure is relatively

uniform. If the dimensions of the two directions

of the space frame are equal, the angle between

the web rod and the lower chord plane is 45

degrees, h0.7s (h is the height of the space

frame, s is the space frame size), and the

lengths of the upper and lower chords and the web

rod are equal, so that the rod Piece

standardization. The space rigidity of the square

pyramid space frame frame is larger than that of

other types of square pyramid space frame frame

and two-way space frame frame, and the amount of

steel used may be slightly higher. This kind of

space frame is widely used at home and abroad due

to standardization of rods and unified nodes,

which is convenient for factory production.

(6), the quadrangular pyramid space frame is

being discharged and evacuated

- The positive discharge and evacuated quadrangular

pyramid space frame is based on the positive

quadrangular pyramid space frame, and some of the

web and lower chords in the quadrangular pyramid

units are appropriately removed, so that the

space frame size of the bottom chord is twice as

large as the space frame size of the top chord. - The number of rods of this kind of space frame is

small, the total number of web rods is about 3/4

of the total number of the web rods of the

quadrangular pyramid space frame frame, and the

lower chord is reduced by about 1/2, so the

structure is simple and the economic effect is

better. - As the surrounding space frames are not suitable

for drawing rods, the number of space frames in

the two directions should be odd. If h0.7s, the

lengths of the upper and lower chords and webs

are equal. The force of this kind of space frame

is similar to that of the orthogonal cross beam

system, and the stiffness is weaker than that of

a quadrangular pyramid.

Positively placed quadrangular cone evacuated

space frame

(7), one-way broken line space frame

- The one-way broken-line space frame is a space

frame made up of a quadrangular pyramid space

frame without the vertical upper and lower

chords, and a circle of longitudinal upper chords

is reserved around it, which is suitable for

peripheral support. - The quadrangular pyramid space frame is placed in

the front, and it is used when the aspect ratio

is greater than 3 in the case of peripheral

support. The unidirectional broken-line space

frame is in a state of unidirectional force, and

the force is transmitted by a V-shaped truss. It

is more rigid than a simple plane truss, and no

support system is required. All members are

stressed members. .

One-way polyline space frame

(8). Place the quadrangular pyramid space frame

diagonally

- The diagonally placed quadrangular pyramid space

frame is also composed of inverted quadrangular

pyramids. The upper chord space frame is placed

orthogonally, and the bottom chord space frame is

placed orthogonally that is, the bottom chord is

perpendicular (or parallel) to the boundary, and

the top chord is at 45 degrees to the boundary.

Angle. The length of the upper chord of this kind

of space frame is equal to 0.7 times the length

of the lower chord. In the case of peripheral

support, the upper chord is compressed and the

lower chord is tensioned. The space frame

reflects the tension of the long rod and the

compression of the short rod, so the force of the

rods is reasonable. In addition, there are

relatively few members that meet at the nodes (6

upper chord nodes and 8 lower chord nodes). When

the height of the space frame is half the length

of the lower chord, the upper chord and the

diagonal web are the same length. This kind of

space frame is suitable for surrounding support,

with simple node structure, reasonable force on

rods, and less steel consumption. It is also a

form that is widely used in domestic engineering.

Inclined quadrangular pyramid space frame

(9). Checkerboard-shaped quadrangular pyramid

space frame

- The checkerboard-shaped quadrangular pyramid

space frame is named because its shape is similar

to that of a chess board. On the basis of the

quadrangular pyramid, except for the surrounding

quadrangular pyramid, the middle quadrangular

pyramid is emptied, the lower chord is placed

orthogonally, the upper chord is orthogonally

placed, and the lower chord is at an angle of 45

degrees with the boundary, and the upper chord is

placed at an angle of 45 degrees. The rod is

perpendicular (or parallel) to the boundary. It

can also be understood as the diagonally placed

quadrangular pyramid net frame rotated 45 degrees

around the vertical axis. This kind of space

frame also has the advantages of short upper

chord and lower chord length, and there are few

intersecting rods on the nodes, and the roof

panel has a single specification, which is

suitable for peripheral support.

Checkerboard-shaped quadrangular pyramid space

frame

(10). Star-shaped quadrangular pyramid space frame

- The star-shaped quadrangular pyramid space frame

is made up of two inverted triangular small

trusses crossing each other. The bottom side of

the two small quilts constitute the upper chord

of the space frame, the upper chord is placed

orthogonally and diagonally, the vertices of each

unit are connected to form the bottom chord, and

the bottom chord is placed orthogonally. The

upper chords are in the same plane. - This kind of space frame also has the

characteristics of short upper chord and lower

chord length, and the force of the rods is

reasonable. When the height of the space frame is

equal to the length of the upper chord, the upper

chord is the same length as the vertical rod, and

the oblique web is the same length as the lower

chord. This kind of space frame is suitable for

peripheral support.

Star-shaped quadrangular pyramid space frame

(11). Triangular cone space frame

- The triangular pyramid system space frame is

composed of inverted triangular pyramids. The

basic unit is a triangular cone. - The triangular pyramid space frame is composed of

inverted triangular pyramids. Both the upper and

lower chord planes are equilateral triangle

meshes. The vertex of the lower chord triangle is

on the centroid projection line of the upper

mystic triangle mesh. The force of the triangular

space frame is uniform. If the height of the

space frame is 2/3 ½ times the space frame

size, the upper and lower chords and web members

of the space frame are of equal length. The

number of intersecting rods at the upper and

lower chord nodes are both 9, and the node

structure types are uniform. Triangular cone

space frame is generally suitable for large and

medium-span buildings and heavy roof buildings.

It is most suitable when the building plan is

triangular, hexagonal or circular.

Triangular cone space frame

(12). Evacuate the triangular cone space frame

- The evacuated triangular pyramid space frame is

based on the triangular pyramid space frame, and

some of the webs and lower chords in the

triangular cones are appropriately removed, so

that the upper chord mesh is still triangles, and

the lower chord mesh is a combination of

triangles and hexagons or all six. For the

combination of polygonal shapes, the rule of

taper tapping in the former is none of the space

frames along the periphery of the space frame

will taper, and the inside will be separated from

the second circle along three directions to

extract a triangular cone. There is a hatched

part in the figure. To remove the mesh of the

cone. The latter starts from the surrounding

space frame, and draws one at two intervals along

three directions. The hatched part in the figure

is the space frame with the cone removed. The

evacuated triangular pyramid space frame has many

rods removed, and the overall rigidity is not as

good as the dipyramidal space frame. It is

suitable for small and medium-span triangular,

hexagonal and circular building planes.

Evacuate the triangular cone space frame

(13). Honeycomb space frame

- The honeycomb triangular pyramid space frame is

composed of inverted triangular pyramids arranged

according to a certain rule. The upper chord

space frame is triangular and hexagonal, and the

lower chord space frame is hexagonal. The upper

chord of this kind of space frame is shorter, the

lower chord is longer, and the force is

reasonable. Each node only converges with 6 rods,

the node structure is unified, and the amount of

steel used is less. The honeycomb triangular

pyramid space frame frame itself is geometrically

variable. It needs to rely on the horizontal

restraint of the support to ensure that its

geometry remains unchanged. Attention should be

paid to the construction and installation. The

analysis shows that the internal forces of the

lower chord and web members and the vertical

reaction force of the support can be obtained

from the static balance condition, and the

internal force of the upper chord is determined

according to the horizontal restraint of the

support. This kind of space frame is suitable for

surrounding small and medium span roofs.

Honeycomb space frame