Composite Sliding Block for Frictional Seismic Isolators
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Solution Overview
Problem
Existing friction-type seismic isolators lack mechanisms to protect their integrity from lateral impacts and vertical lifting, which can cause significant inelastic deformations and potential collapse, especially due to foundation failure or isolator lifting during earthquakes.
Innovation Solution
A composite sliding block is introduced for friction-type seismic isolators, incorporating energy dissipation elements and axially flexible components to mitigate horizontal and vertical impacts. The sliding block features a high-friction interface and an elastomeric seal to absorb and dissipate impact energy, while elastomeric compression supports help absorb vertical loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional friction-type seismic isolators are used, then they allow energy dissipation through friction, but they lack protection mechanisms against lateral impacts and vertical lifting causing inelastic deformations
Solution Approach 1:
The sliding block is divided into multiple components: a first contact component, a second contact component, and an energy dissipation element positioned between them. This segmentation allows each component to perform specific functions - the contact components interface with support plates while the energy dissipation element protects against impacts, thereby improving reliability without requiring a completely new device design
Solution Approach 2:
The energy dissipation element is nested between the two contact components within the sliding block structure. This nested arrangement allows the protective mechanism to be integrated into the existing sliding block without significantly increasing overall device complexity, as the energy dissipation element is contained within the space already defined by the contact components
2Reliability
If simple sliding blocks are used, then manufacturing is easier and cost is lower, but they cannot dissipate impact energy and protect against lateral impacts
Solution Approach 1:
The energy dissipation element changes the mechanical parameters of the sliding block by introducing controlled flexibility and energy absorption capacity. This element can be designed with specific material properties and geometric parameters to dissipate impact energy, allowing the block to protect against lateral impacts while maintaining manufacturability through standardized component design
3Reliability
If rigid sliding blocks are used, then they provide stable support, but they concentrate stresses and cause metal-to-metal contact during vertical impact
Solution Approach 1:
The energy dissipation element acts as a flexible component between the rigid contact components, preventing direct metal-to-metal contact during vertical impact. This flexible element distributes and absorbs impact stresses, reducing stress concentrations while maintaining the stable support function of the rigid contact components
Solution Approach 2:
The energy dissipation element is pre-positioned between the contact components to provide cushioning before vertical impact occurs. This beforehand cushioning mechanism ensures that when vertical impact happens, the flexible element is already in place to absorb the shock and prevent direct contact between metal surfaces, thereby reducing stress concentrations
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composite sliding block enhances the resilience of seismic isolators to both horizontal and vertical impacts, reducing stress concentrations and preventing metal-to-metal contact, thereby improving structural integrity and performance during extreme earthquakes.
Implementation Method 1
an elastomeric seal arranged between the first contact component and the second contact component... capable of laterally being compressed by the effect of a relative displacement between the two contact components
Implementation Method 2
the elastomeric seal... dissipates energy
Implementation Method 3
Two types of forces are generated on each sliding surface: (i) forces perpendicular to such surfaces, generically referred to as normal reactions; and (ii) friction forces parallel to such surfaces
Implementation Method 4
elastomeric compression supports arranged respectively between each low-friction sliding plate and a bottom of a corresponding niche in a confined manner... to absorb vertical loads
Data Source
AI summary
A composite sliding block to be arranged between two supporting plates of a frictional-type seismic isolator, with one supporting plate connected to the superstructure to be isolated and the other to the foundations, comprising two contact components that externally are slidingly or articulatedly in contact with said supporting plates, depending on whether the isolator has one or two sliding surfaces, and internally are coupled to each other by means of a male projection of one component in a female recess of the other. An elastomeric seal occupies an empty space surrounding the projection within the recess and, on the external side of the contact component(s) slidingly in contact with the supporting plate(s), a sliding plate is accommodated in a corresponding niche having an elastomeric compression support at the bottom. Frictional pendulum-type isolators with one or two concave sliding surfaces include such a block.