How to Balance Stiffness and Toughness in Building Structural Parts?
Publish Time: 2025-11-19
Building structural parts, as the "skeleton" of a building, bear the core mission of transmitting loads, resisting external forces, and maintaining overall stability. Under complex conditions such as earthquakes, strong winds, temperature changes, and even sudden impacts, the structure needs sufficient stiffness to control deformation and ensure functionality, while also possessing appropriate toughness to dissipate energy and prevent brittle failure. The design of building structural parts is key and the core path to achieving the seismic fortification goal of "no damage in minor earthquakes, repairable in moderate earthquakes, and no collapse in major earthquakes."1. Stiffness: Ensuring Stability and Comfort under Normal UseStiffness reflects the structure's ability to resist deformation. Excessive deflection or lateral displacement not only affects the opening of doors and windows and causes cracks in partitions, but also causes psychological anxiety for users. Therefore, under normal loads, components such as beams, columns, and shear walls must possess sufficient stiffness. For example, high-rise buildings improve overall lateral stiffness by using core tubes, braced frames, or outrigger trusses; large-span roofs use prestressed technology or spatial grid structures to suppress vertical deformation. This "rigid" design ensures the functionality and comfort of the building in daily use, serving as the first line of defense for structural safety.2. Toughness: Giving the structure the ability to "overcome rigidity with flexibility"However, excessive stiffness does not necessarily guarantee safety. In extreme events, an overly rigid structure absorbs a large amount of energy but cannot effectively dissipate it, leading to a sudden increase in stress and sudden fracture—a phenomenon known as "brittle failure." Toughness, on the other hand, is the ability of a structure to withstand loads and undergo significant plastic deformation without collapsing after yielding. By rationally configuring ductile steel reinforcement, using confined concrete, and installing energy-dissipating beams or dampers, the structure can "bend without breaking" under controllable damage conditions, swaying and surviving like bamboo in a storm. This "toughness" is the last line of defense for life safety.3. Balance of Rigidity and Flexibility: Achieving Performance Synergy through Materials and ConstructionBuilding structural parts achieve an organic unity of rigidity and toughness at the component level through material combinations and detailed construction. For example, steel-concrete composite columns combine the high toughness of steel with the high stiffness of concrete, with the outer steel tube confining the core concrete, significantly improving load-bearing capacity and ductility. Steel-concrete composite beams utilize a steel frame to provide initial stiffness, while the reinforcement and concrete work together to enhance later deformation capacity. In node design, the principle of "strong nodes, weak members" is emphasized, ensuring that plastic hinges appear at beam ends rather than columns or connections, creating multiple seismic defense lines in the overall structure. This design philosophy of "rigid where necessary, flexible where appropriate" allows the structure to perform its functions and work collaboratively at different stress stages.4. System Optimization: Controlling Stiffness and Toughness Distribution Through Overall LayoutThe balance between stiffness and toughness is not only reflected in individual components but also requires overall planning at the structural system level. Regular, symmetrical planar layouts can avoid torsional effects and ensure uniform stiffness distribution; gradual vertical stiffness design prevents the emergence of "soft layers" or "weak layers"; localized stiffness reinforcement in critical areas and appropriate release of constraints in non-critical areas guides plastic development. Furthermore, the introduction of seismic isolation and energy dissipation technologies transforms the "rigid-flexible" contradiction into an "isolation-dissipation" strategy—isolieving seismic energy through rubber bearings or actively dissipating vibrations using metal dampers, fundamentally reducing the stress requirements of the main structure and achieving a higher level of performance balance.The rigidity and flexibility of building structural parts are like yin and yang, indispensable to each other. Rigidity ensures daily stability, while flexibility safeguards survival in times of crisis. Contemporary structural engineering has transcended the traditional mindset of "strength above all else," shifting towards performance-oriented, refined design. Through material innovation, structural optimization, and system integration, engineers are constantly exploring the optimal balance between rigidity and flexibility, enabling buildings not only to stand firm but also to confidently withstand the tests of nature, constructing a truly "living" spatial framework that balances safety, economy, and aesthetics.
