Tower Crane Chord Cross-Section Optimization
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Solution Overview
Problem
Existing crane designs face challenges in achieving optimal weight and strength due to constant cross-sectional profiles in longitudinal chords, leading to oversizing and increased weight, and the use of high-strength steel complicates manufacturing and increases costs, while fiber-reinforced materials lack impact resistance.
Innovation Solution
Adapting longitudinal chord cross-sections to varying force conditions within truss sections without welding, using a single-piece, homogeneous steel or steel profile with weld-free transitions and profile widenings at connection points for stress reduction, allowing for varying cross-sections and reduced material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If longitudinal chords are designed with constant cross-section to simplify manufacturing, then ease of manufacture is improved, but weight increases due to oversizing in weaker sections
Solution Approach 1:
The longitudinal chords are designed with varying cross-sections tailored to the specific force conditions in each truss field. Sections with higher tensile forces have larger cross-sections, while sections with lower forces have smaller cross-sections, optimizing material usage and reducing overall weight without compromising structural integrity
Solution Approach 2:
The longitudinal chords are divided into multiple sections with different cross-sections corresponding to different framework fields. Each section is optimized for its specific load conditions, allowing the structure to achieve weight optimization while maintaining manufacturing feasibility through modular assembly
2Weight of moving object
If different belt parts are assembled and welded to achieve varying cross-sections, then weight optimization is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The cross-sectional parameters of the longitudinal chords are varied continuously or stepwise along their length to match the varying force conditions in different truss fields. This allows weight optimization through localized parameter adaptation without requiring complex assembly of multiple different components
Solution Approach 2:
The chord cross-sections are designed to dynamically adapt to the changing force conditions along the span, with each section optimized for its specific position in the framework, achieving weight reduction while maintaining manufacturing simplicity through standardized production methods
3Strength
If high-strength steel is used to achieve optimal strength-to-weight ratio, then strength is improved, but manufacturing difficulty and cost increase
Solution Approach 1:
High-strength steel is selectively applied in sections where the forces are greatest, while lower-strength materials can be used in sections with lower load demands. This localized material optimization achieves the required overall strength while reducing manufacturing complexity and cost compared to using high-strength steel throughout the entire structure
4Weight of moving object
If fiber-reinforced materials are used to reduce weight, then weight is improved, but impact and shock resistance deteriorate
Solution Approach 1:
The structure utilizes composite material systems that combine the high strength-to-weight ratio of fiber-reinforced materials with the impact resistance of traditional steel components. This hybrid approach achieves weight reduction while maintaining the reliability and shock resistance required for crane operations in harsh conditions
Data Source
Figure 1
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AI summary
The present invention relates to a crane, in particular a tower crane, with at least one truss girder (7) comprising several longitudinal chords (8, 9) connected to one another by transverse and/or diagonal members (10), wherein at least one of the longitudinal chords (8) has a chord cross-section that changes along its length and/or different chord cross-sections in different truss bays (11, 12, 13). According to the invention, the at least one longitudinal chord (8) having a chord cross-section that changes along its length or different chord cross-sections in different truss bays (11, 12, 13) has weld-free transitions between chord sections of different chord cross-sections, wherein the longitudinal chord (8) comprises a profile widening (18) at at least one connection point (14, 15, 16, 17) of a transverse and/or diagonal member (10), from which the chord cross-section decreases on both sides in the longitudinal direction of the chord.