Seismic Retrofitting Frame for Buildings with Overhangs
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Solution Overview
Problem
Existing seismic retrofitting methods for buildings with overhangs require additional foundations and can cause large drawing forces, making them uneconomical and difficult to implement, especially when the foundation construction is challenging.
Innovation Solution
A retrofitting structure that surrounds the overhang on the outer wall surface using a reinforcing frame with vertical and horizontal truss members, connected via anchors, which transmits horizontal and vertical forces without the need for additional foundations, allowing seismic retrofitting on any floor without blocking the view or requiring tendons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a steel brace structure is added on an existing foundation beside the outer wall surface, then seismic retrofitting can be performed while allowing building use, but additional foundations must be constructed which increases complexity and cost especially when clearance limits are approached
Solution Approach 1:
The patent combines the seismic retrofitting function with the existing building foundation by integrating the steel brace structure into the existing foundation system. The steel braces are anchored to the existing foundation through connection plates and anchor bolts, merging the new seismic reinforcement with the existing structural base, thereby avoiding the need for separate additional foundations.
Solution Approach 2:
The existing foundation is made to serve dual purposes: its original load-bearing function and the new function of supporting the seismic retrofitting steel brace structure. By designing connection details that utilize the existing foundation's capacity, the system achieves multi-functionality, eliminating the need for separate foundation construction.
2Ease of manufacture
If a framed steel brace is directly attached to the outer wall surface, then construction is simplified, but the method is not suitable for walls with overhangs such as balconies, eaves or louvers due to interference
Solution Approach 1:
The steel brace structure is divided into modular components including steel braces, connection plates, and anchor bolts. This segmentation allows the system to be assembled in sections that can navigate around architectural features like overhangs, maintaining construction simplicity while adapting to complex wall geometries.
Solution Approach 2:
Connection plates serve as intermediary elements between the steel braces and the building structure. These plates can be positioned at appropriate locations that avoid interference with overhangs while still providing effective load transfer, thus mediating between the simplified direct-attachment approach and the need to accommodate architectural features.
3Strength
If anchor bolts are used to fix the reinforcing frame to outer beams, then the frame can be attached, but large drawing forces act on the anchor bolts requiring through holes and tendons which increases complexity
Solution Approach 1:
The connection design uses multiple anchor bolts distributed across the connection plate rather than relying on a few high-capacity bolts. This partial action approach spreads the drawing forces across multiple connection points, reducing the demand on each individual anchor bolt and eliminating the need for complex tendon systems while maintaining overall connection strength.
4Loss of energy
If retrofitting is performed on middle-level or top-level floors only, then seismic retrofitting can be targeted, but a foundation must still be added which requires constructing unnecessary steel braces for lower-level floors
Solution Approach 1:
The steel brace structure is designed with local quality by providing braces and connection details only at the specific floors requiring seismic retrofitting (middle-level or top-level floors). The structure is not uniformly distributed throughout the entire building height, but rather tailored to the specific structural needs of each floor, eliminating unnecessary components and reducing overall complexity and cost.
Data Source
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AI summary
Provided is a retrofitting structure for existing building that does not require the addition of a foundation specific to the retrofitting structure, can implement seismic retrofitting at any floors only of the existing building, and hardly causes a large drawing force resulting from eccentric bending moment that may act on the seismic retrofitting structure. A retrofitting structure 100 for existing building includes: a reinforcing frame 10 including a frame member 11 and a vibration control member 12 interposed in the frame member, the reinforcing frame being provided on an outer wall surface of an existing building B having an overhang T on the outer wall surface so as to surround the overhang T; and a vertical truss member 30 and a horizontal truss member 20 configured to couple the reinforcing frame 10 and the outer wall surface.