Seismic Isolation Structure for Steel Plant Supports

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Solution Overview

Problem

Existing seismic isolation methods for plant support structures with high floor heights face challenges in ensuring horizontal rigidity and stability due to the need for large-scale construction, potential damage to plant functions, and difficulties in applying conventional seismic isolation techniques to brace structures.

Innovation Solution

A structure for seismic isolation is provided on a structure plane with a seismic isolation device placed between columns and a horizontal rigid bearing element, including a connection beam and vertical braces, to enhance bending and horizontal rigidity, allowing for stable seismic behavior without extensive construction or damage to plant functions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a seismic isolation device is provided in an intermediate position of a column between beams, then seismic isolation is achieved, but the distances above and below the device are longer than the device itself, which prevents bending rigidity in a horizontal direction from being ensured

Engineering Contradiction:

Improveseismic isolation performanceVSAvoidhorizontal rigidity of seismic isolation layer

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The column is divided into segments by introducing bearing portions at specific locations. The seismic isolation device is positioned between these bearing portions, creating distinct functional segments: upper bearing portion, seismic isolation device, and lower bearing portion. This segmentation allows the long column to be divided into manageable sections that can collectively provide both seismic isolation and horizontal rigidity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Bending reinforcement bars are concentrated in specific local regions - the upper and lower bearing portions - rather than uniformly distributed throughout the column. This local quality enhancement provides the necessary horizontal rigidity at critical locations while allowing the middle section to accommodate the seismic isolation device with appropriate clearance.

Inventive Principle:

Principle #3Local quality

2Reliability

If seismic isolation retrofit is performed on a foundation, then seismic isolation is achieved, but large-scale construction on the foundation is required, which increases suspension period of plant functions and may damage plant functions provided on foundation

Engineering Contradiction:

Improveseismic isolation performanceVSAvoidsuspension period of plant functions

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The bearing portions and seismic isolation device are installed in a predetermined sequence during the retrofit process. Support members are temporarily installed to maintain structural stability during the installation of bearing portions, and the seismic isolation device is positioned between them. This preliminary structuring of the installation process enables efficient execution without requiring extensive temporary plant shutdowns.

Inventive Principle:

Principle #10Preliminary action

3Strength

If cast-in-place concrete is placed over a height substantially corresponding to one floor on an outer periphery of the existing column, then rigidity is improved, but labor requirements increase and suspension period of plant increases

Engineering Contradiction:

Improverigidity of seismic isolation layerVSAvoidconstruction efficiency

Core Design Contradiction:

StrengthVSProductivity

Solution Approach 1:

The invention extracts and removes the need for extensive cast-in-place concrete work by using a different structural approach. Instead of placing concrete over the full floor height, the solution uses bearing portions with concentrated bending reinforcement bars and support members to achieve the necessary rigidity. This extraction of the concrete placement requirement significantly reduces labor and construction time.

Inventive Principle:

Principle #2Taking out (Extraction)

4Device complexity

If a brace structure is used in plant support structures, then structural simplicity is maintained, but removing a brace prevents rigidity and strength of the seismic isolation layer from being ensured

Engineering Contradiction:

Improvestructural simplicityVSAvoidrigidity and strength of seismic isolation layer

Core Design Contradiction:

Device complexityVSStrength

Solution Approach 1:

The bearing portions serve multiple functions simultaneously: they provide structural connection points, concentrate bending reinforcement to ensure horizontal rigidity, and create the necessary clearance space for the seismic isolation device. This multi-functionality allows the brace structure to maintain its simplicity while still ensuring the rigidity and strength of the seismic isolation layer through the strategically designed bearing portions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS10309643B2Structure for seismic isolation, steel support structure, and method for seismic isolation of existing steel support structures

Publication Date: 2019.06.04 MITSUBISHI POWER LTD

AI summary

A structure for seismic isolation 10 provided on a structure plane 17 including a pair of left and right columns 5, 5 spaced apart in a horizontal direction, and a pair of upper and lower beams 7A, 7B spaced apart in a vertical direction, wherein the structure for seismic isolation comprises: a seismic isolation device 11 provided in a middle of each of the column 5, 5 to be displaced toward the beam 7A; and a horizontal rigid bearing element that is provided between an area in which the seismic isolation device 11 is provided and the beam 7B and that includes a connection beam 13 connecting the pair of columns 5, 5 and vertical braces 15L, 15R.