Structural joints connecting H or I sections

General

Basis

(1) This section contains design methods to determine the structural properties of joints in frames of any type. To apply these methods, a joint should be modelled as an assembly of basic components, see 1.4(1).
(2) The basic components used in this Standard are identified in Table 6.1 and their properties should be determined in accordance with the provisions given in this Standard. Other basic components may be used provided their properties are based on tests or analytical and numerical methods supported by tests, see EN 1990.
NOTE: The design methods for basic joint components given in this Standard are of general application and can also be applied to similar components in other joint configurations. However the specific design methods given for determining the design moment resistance, rotational stiffness and rotation capacity of a joint are based on an assumed distribution of internal forces for joint configurations indicated in Figure 1.2. For other joint configurations, design methods for determining the design moment resistance, rotational stiffness and rotation capacity should be based on appropriate assumptions for the distribution of internal forces.

Analysis, classification and modelling

Global analysis

General

(1) The effects of the behaviour of the joints on the distribution of internal forces and moments within a structure, and on the overall deformations of the structure, should generally be taken into account, but where these effects are sufficiently small they may be neglected.
(2) To identify whether the effects of joint behaviour on the analysis need be taken into account, a distinction may be made between three simplified joint models as follows:
– simple, in which the joint may be assumed not to transmit bending moments;
– continuous, in which the behaviour of the joint may be assumed to have no effect on the analysis;
– semi-continuous, in which the behaviour of the joint needs to be taken into account in the analysis.

Eurocode 3: Design of steel structures - Part 1-8: Design of joints

Design assumptions
(1) Joints shall be designed on the basis of a realistic assumption of the distribution of internal forces and moments. The following assumptions shall be used to determine the distribution of forces:
(a) the internal forces and moments assumed in the analysis are in equilibrium with the forces and moments applied to the joints,
(b) each element in the joint is capable of resisting the internal forces and moments,
(c) the deformations implied by this distribution do not exceed the deformation capacity of the fasteners or welds and the connected parts,
(d) the assumed distribution of internal forces shall be realistic with regard to relative stiffnesses within the joint,
(e) the deformations assumed in any design model based on elastic-plastic analysis are based on rigid body rotations and/or in-plane deformations which are physically possible,
(f) any model used is in compliance with the evaluation of test results (see EN 1990).

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照片处理前后对比

动态振荡的阻尼

在模型中加入阻尼的两个原因：限制数值振荡、为系统增加物理的阻尼，ABAQUS/Explicit提供的在分析中加入阻尼的方法：体粘性、粘性压力、材料阻尼、离散减振器。

体粘性

体粘性引入了与体积应变相关的阻尼，目的是改进对高速动力学事件的模拟。ABAQUS/Explicit包括体粘性的线性和二次的形式，体粘性参数一般很少修改默认值，仅作为一个数值影响，在材料点的应力中不包括体粘性压力，所以并不作为材料本构响应的一部分。