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Method for judging cause of dynamic destruction of single-layer network shell structure under earthquake action

A single-layer reticulated shell and dynamic technology, applied to arch structures, dome structures, building components, etc., can solve problems such as rod instability, inability to accurately simulate mechanical properties, and difficulty in determining

Inactive Publication Date: 2011-07-20
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When finely simulating the whole process of the dynamic response of a single-layer reticulated shell structure, there are two problems when using the beam element in the general finite element software to simulate the member: (1) the accuracy of the element stiffness matrix
(2) Simulation problem of bar instability phenomenon
If multiple beam elements are used to simulate a bar, it is impossible to accurately simulate the mechanical properties of the bar after instability, and it is also impossible to simulate the plastic hinge that may appear at the end of the bar and the middle section of the bar. How many beam units are divided into one bar? In order to accurately simulate the phenomenon of member instability, it is difficult to determine

Method used

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  • Method for judging cause of dynamic destruction of single-layer network shell structure under earthquake action
  • Method for judging cause of dynamic destruction of single-layer network shell structure under earthquake action
  • Method for judging cause of dynamic destruction of single-layer network shell structure under earthquake action

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0071] Taking the Kiewitt type single-layer spherical reticulated shell structure with a span of 40m and a rise-to-span ratio of 1 / 3 as an example, the rods are made of three round steel pipes of Φ114×3.0, Φ127×3.5, and Φ140×4.5, and the applied force is 2.0kN / m 2 The surface load of the material is Q235. Enter the three-way El Centro wave and adjust the peak acceleration to 620gal.

[0072] Adopt method step (1) to step (5) of the present invention:

[0073] (1) Complete the incremental step balance iteration;

[0074] The solution process is as follows:

[0075] Step 101: Using the Newmark time integration method to solve the structural nonlinear dynamic balance equations, each iteration obtains the displacement increment Δu of the rod end;

[0076] Step 102: Let the two ends of the bar be numbered as I and J, and the equilibrium equation at the I end is

[0077] F iI = Σ J = ...

Embodiment 2

[0099] Taking the three-way grid single-layer cylindrical reticulated shell structure with a span of 15m, a length of 21m, and a rise-span ratio of 1 / 2 as an example, the rods are made of three round steel pipes of Φ114×3.0, Φ127×3.5, and Φ140×4.5. 1.0kN / m 2 The surface load, the material is Q235, and the three-way El Centro wave is input, and the duration is 12s. In order to simulate the failure process of the structure, the acceleration peak value is adjusted to 620gal.

[0100] Adopt method step (1) to step (5) of the present invention to judge and show that the bar end section of the bar under the earthquake action produces plastic zone at first, along with the increase of load, the bar end section of a plurality of bar parts forms plastic hinge, and the bar end section Unable to bear greater bending moment and shear force, the deformation increases rapidly. If the earthquake action is strengthened at this time, the internal force redistribution of the structure will occu...

Embodiment 3

[0107] Taking the 48m long, 30m wide, single-layer elliptical parabolic reticulated shell structure with single-layer elliptical parabolic lattice structure with one-way slanting rods with a rise-to-span ratio of 1 / 3 as an example, the rods adopt Φ114×4.0, Φ121×4.0, Φ146×6.0 and Φ152× 6.0 four kinds of round steel pipes, apply 1.0kN / m 2 The surface load, the material is Q235, and the three-way El Centro wave is input, and the duration is 12s. In order to simulate the failure process of the structure, the acceleration peak value is adjusted to 620gal.

[0108] Judging from steps (1) to (5) of the method of the present invention shows that a large number of unstable rods and rod-end plastic hinges appear under earthquake action, and there are two types of unstable rods in the structure. The time-varying curves of the number of unstable members and the number of plastic hinges at the rod end are as follows: Figure 9 , Figure 10shown. During the earthquake, the structural mem...

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Abstract

The invention discloses a method for judging cause of dynamic destruction of a single-layer network shell structure under the action of an earthquake, comprising the following steps of: (1) completing incremental step equilibrium iteration; (2) substituting a rod piece rod end force obtained when each time incremental step is finished into an unstability judging equation of an ISO (international standardization organization) round steel pipe to judge whether a structural rod piece is unstable or not; (3) if the structural rod piece is not unstable, simulating the rod piece according to the method in the step (1) to calculate thrusts at the two ends of the rod piece, if the structural rod piece is unstable, simulating the rod piece according to a Marshall model; (4) judging the unstability type of the rod piece; and (5) determining that dynamic destruction is caused as the dynamic bearing capacity of the structure and the earthquake action can not be balanced when the nonlinear dynamic equilibrium equation set of the structure can not be converged after iteration for 15 times. By adopting the invention, the process of unstable-straightening and plastic hinge forming-disappearing which can be repeatedly experienced by the rod piece under the action of the earthquake can be simulated.

Description

technical field [0001] The invention relates to a spatial grid structure, in particular to a method for judging the cause of dynamic damage of a single-layer reticulated shell structure under earthquake action. Background technique [0002] The single-layer reticulated shell structure is a spatial structure composed of a large number of rods according to certain geometric laws. Under the action of dynamic load, the reticulated shell structure undergoes repeated loading-unloading processes, resulting in repeated instability-straightening, plastic hinge formation-disappearance of the rods During the process, the mechanical properties of the members are in dynamic changes, resulting in dynamic changes in the bearing capacity of the structure. Therefore, in order to obtain accurate real-time dynamic response of the single-layer reticulated shell structure, it is necessary to establish a member calculation model that can simulate the real-time mechanical properties of the members....

Claims

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Application Information

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IPC IPC(8): E04B1/32
Inventor 丁阳齐麟李忠献
Owner TIANJIN UNIV
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