CN-121977004-A - Rectangular web-steel pipe composite space node structure with continuous rigidity distribution

CN121977004ACN 121977004 ACN121977004 ACN 121977004ACN-121977004-A

Abstract

The invention discloses a rectangular web-steel pipe composite space node structure with continuous rigidity distribution, which is suitable for the intersecting connection of a main pipe and a diagonal brace of an offshore wind power jacket. The node is provided with a rectangular web plate with a space curved surface on the outer wall of a main pipe, and continuous curvature and continuous thickness distribution are formed through a web plate abduction function, a thickness gradual change function and a smooth transition surface, so that the outer surface of the node is continuous in normal direction and curvature. The web curved surface is defined by parameterization, the abduction quantity is changed smoothly in the width and height directions, and the thickness is enhanced locally according to the direction of the diagonal brace, so that the bending moment, axial force and shearing force input by the diagonal brace form planar diffusion on the web curved surface, and the abrupt turning of the traditional node force flow in a narrow intersecting band is avoided. The smooth transition surface between the main pipe and the web ensures that the whole structure has no geometric mutation. The invention obviously reduces the hot spot stress and stress gradient, improves the fatigue life of the node, and is suitable for offshore wind power jacket and large steel structure nodes bearing cyclic loads.

Inventors

LI TAO
WANG XUEFENG
TANG CAN
Wu Zehou
WANG GANG
Gao Daifan

Assignees

长江三峡集团江苏能源投资有限公司
中国电建集团华东勘测设计研究院有限公司

Dates

Publication Date: 20260505
Application Date: 20251216

Claims (9)

1. A rectangular web-steel tube composite spatial node structure with continuous stiffness distribution, comprising: The node structure consists of a main pipe section, two diagonal bracing sections and a rectangular web plate shell arranged outside the intersecting area of the outer wall of the main pipe and the diagonal bracing; The web shell is a space curved surface with continuous curvature distribution and continuous thickness change, and is respectively connected with the main pipe section and the diagonal bracing section through the smooth transition curved surface, so that a continuous area between the main pipe and the diagonal bracing forms a continuous curvature and continuous rigidity composite node interface; Wherein: (1) The outer surface of the web shell is represented by a two-dimensional parametric surface S(u,v)=r 0 +ut 1 +vt 2 +w(u,v)n t Wherein t 1 and t 2 are web plane main direction vectors, n t is a main pipe outer wall normal direction, and w (u, v) controls web abduction distance; (2) The web surface abduction amount is controlled by an abduction function w (u, v) to enable the web to have controllable curvature and spatial abduction capability in the width direction and the height direction, and the expression is that (3) The main curvature kappa 1 and the auxiliary curvature kappa 2 of the outer surface of the web plate meet the following conditions: And meets engineering continuity constraints: (4) The variation of the web thickness along the direction angle θ, width u, and height v satisfies: the thickness change rate is limited to: (5) The smooth transition curved surface between the outer wall of the main pipe and the web boundary satisfies the following conditions: P(s,l)=(1-s)X tube (l)+sS edge (l)+s(1-s)Q(l) And has normal continuous conditions:
2. The spatial node structure of claim 1, wherein the strut-web intersection line is defined by the strut outer surface equation: and the web curved surface equation S (u, v) is combined.
3. The space node structure of claim 1 wherein the force flow spreading capability of the diagonal braces after entering the web is modified by: Wherein the parameter is The relative ratio of diagonal strut projection width to web width is characterized.
4. The space node structure of claim 1, wherein the equivalent bending moment M eq borne by the web is satisfied, Wherein M s is the diagonal end bending moment.
5. The space node structure of claim 1, wherein the web assumes an equivalent film force N eq of: Wherein F s is the axial force of the diagonal brace, and D s ,D m is the diameters of the diagonal brace and the main pipe respectively.
6. The spatial node structure of claim 1, wherein the node outer surface equivalent stress σ eq satisfies: wherein the hot spot stress amplification factor is: K s (α)＝1.05+0.82α+0.19α 2 。
7. The spatial node structure of claim 1, wherein the node surface stress gradient G satisfies: wherein R m is the mean radius of curvature of the main pipe.
8. The spatial node structure according to claim 1, characterized in that its fatigue equivalent stress range Δs satisfies: ΔS=1.18σ eq [1+0.25λ] and the method is used for evaluating the fatigue life under the long-term cyclic load.
9. The space node structure according to any one of claims 1 to 8, wherein the node structure enables bending moment, axial force and shearing force of the diagonal brace in the intersecting area to form planar diffusion on the web curved surface through the synergistic effect of continuous curvature distribution, thickness gradual change function, smooth transition curved surface and force flow diffusion correction model of the web shell, thereby remarkably reducing node hot spot stress and stress gradient, improving fatigue life of the node under the cyclic loading effect of the offshore wind power jacket, and realizing the integral structure of the composite space node with continuous geometry, continuous rigidity and continuous force flow characteristics.

Description

Rectangular web-steel pipe composite space node structure with continuous rigidity distribution Technical Field The invention belongs to the field of offshore wind power structural engineering and steel pipe node construction, and particularly relates to a novel rectangular web-steel pipe composite space node structure for a junction of a main pipe and an inclined strut of an offshore wind power jacket. According to the structure, the web shell with continuous thickness and smooth curvature is additionally arranged on the outer wall of the main pipe, so that the force flow transmitted by the diagonal brace is distributed in the web area, the stress transmission mode of the node is improved, the hot spot stress is reduced, the fatigue life of the node is prolonged, and the structure is suitable for the design requirement of the high-reliability node of the high-capacity offshore wind turbine. Background Along with the continuous expansion of the scale of the offshore wind turbine, the single machine capacity is improved to 12MW or even higher, and the scale and the stress of the jacket foundation are improved. The jacket is composed of a plurality of steel pipes such as a main pipe, an inclined strut, a horizontal strut and the like, and the connecting joint between every two members is the most concentrated stress and most sensitive fatigue part in the whole structure. Under the combined action of long-term wind, wave and flow multiaxial cyclic loads, the stress amplitude and the stress gradient at the node are often obviously higher than those of the component body, and hot spot stress is particularly easy to occur in the intersecting area of the main pipe and the diagonal brace. Extensive engineering experience has shown that fatigue damage to conventional intersecting nodes typically occurs earliest near the weld toe and rapidly weakens the node's load carrying capacity in the form of crack initiation and propagation. The root cause of the above phenomenon is that the conventional "tube-tube direct intersection" form has natural geometrical defects. The main pipe and the outer wall of the diagonal brace are intersected with different curvatures in the space, obvious curvature mutation exists near the intersecting line, so that the normal direction of the outer surface is changed drastically in an extremely short distance, and force flow has to make sharp rotation along a narrow intersecting band, so that stress lines are densely accumulated to form a typical hot spot area. Particularly, under the combination of a large-diameter main pipe and a large-inclination angle inclined strut, the stress non-uniformity of a intersecting area is further amplified, the local secondary bending effect is obviously enhanced, and the fatigue life of the node is greatly shortened. In order to improve node performance, the traditional design often reduces stress concentration by means of stiffening plates, increasing local thickness, expanding weld toe fillets and the like. However, these methods are mostly "compensation type reinforcement" and cannot eliminate curvature break points from the geometric nature, and on the contrary, the edge or thickness jump position of the reinforcement plate will form new rigidity abrupt change, so that the stress concentration area will migrate from the intersecting line position to the transition edge of the reinforcement plate, and the phenomenon of "hot spot movement but not disappearance" will often occur in engineering. In addition, the large-scale offshore wind power node is complex to manufacture, the number of welding lines is large, and the internal undetectable areas are large, so that the traditional reinforcement mode still has limitations in terms of construction quality and fatigue reliability. As offshore wind power enters a deep hydration and large capacity stage, a novel structural system capable of realizing geometric continuity, rigidity continuity and force flow continuity is needed for jacket nodes, and the stress environment of the nodes is radically improved. Disclosure of Invention The invention aims to solve the problems of stress concentration protrusion, severe force flow deflection and insufficient fatigue life of the traditional node at the intersecting position of a main pipe and an inclined strut of an offshore wind power jacket, and provides a composite node structure for realizing continuous rigidity and continuous curvature by utilizing a rectangular web shell. A rectangular web plate with a space curved surface is arranged on the outer wall of the main pipe, and the web plate is continuously connected with the main pipe through a smooth transition surface, so that a triple improvement mechanism of 'planar diffusion-gradual change rigidity-continuous curvature transition' of a diagonal bracing incoming force flow is realized, and the joint is systematically improved in three layers of geometric form, stress mode and fatigue performance. For this purpose,