Project Details
Project Details
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Call RFCS-2019
Funding scheme: RFCS-REA
Proposal number: 800716
Proposal acronym: HYCAD
Duration (months): 36
Proposal title: Innovative steel-concrete hybrid coupled walls for buildings in seismic areas: advancements and design guidelines
Activity: Steel
The research project HYCAD is devoted to the development of design, detailing, and construction of an innovative seismic-resistant steel-concrete hybrid coupled wall (HCW) system originally introduced in the 2011-2014 RFCS research project INNO-HYCO. Such system was shown through numerical analyses and experimental tests to have very encouraging potentialities in seismic areas. Important results were achieved at the end of INNO-HYCO for the HCW solution regarding:
Proof of concept
Tentative design procedure
Preliminary testing (shear links)
Application to one case study
Innovative hybrid coupled wall system?
The basic coupled wall system investigated during INNOHYCO and now in HYCAD consists of a reinforced concrete (RC) shear wall coupled to two steel side columns by means of steel links (steel I-profiles or dissipative devices).
The RC wall carries almost all the horizontal shear force while the overturning moments are partially resisted by an axial compression-tension couple developed by the two side steel columns rather than by the individual flexural action of the wall alone.
Some critical questions and research points however remained unexplored as listed below and therefore additional investigations were deemed indispensable to foster its adoption in the construction market; such as:
Which type of links (bending, intermediate or shear) should be used to have an optimum performance?
Can dissipative devices further improve the HCW system's performance as well as make way for easier post-damage restoration efforts?
What should be a simplified yet efficient method to analyze the HCW systems?
Which behavioral factor (q) should be used for Structural analysis? Should we consider the higher modes?
How to avoid the overcrowded connection zones between the reinforced concrete wall and the steel link?
Standard design methods and optimized solutions - missing support for the daily design and pre-normative documents
Links - I-profiles or dissipative devices?
To improve and optimize the global seismic performance of the HCW systems, different types of links will be investigated. Bending and shear critical I-profiles will be used in some case studies whereas special types of dissipative devices will also be studied numerically and experimentally.
Specific attention will also provided to the post-damage repair efforts. Restoration of a dissipative device will be compared with the restoration of a simple steel I-profile to check their portability.
Link-to-wall connections
During the INNOHYCO investigations, the steel links were connected to the reinforced concrete wall via embedded steel profiles. These embedded profiles were inserted through the boundary zones of the RC wall. Now, as shear walls are commonly designed with heavily reinforced boundary zones, the link-to-column connection became quite overcrowded and very difficult to construct/detail.
So, new types of link-to-wall connections will be studied in the HYCAD project where post-tensioned tendons/shear studs/pre-stressed cables will be used to avoid such an issue without making any compromise regarding the structural performance.
Composite walls
A composite wall is basically a concrete wall with embedded steel profiles acting as additional reinforcements. Such walls will be used in different configurations for three primary reasons -
It can improve the overall bending performance of the wall
Additional reinforcements in the boundary zone can be avoided
The link can be directly connected to the embedded profiles
Six options have been identified in order to improve the HCW system previously designed in INNO-HYCO
Post-tensioned link-to-wall connections
Substitution of conventional re-bars by steel profiles (composite wall)
Wall with rocking basis
Use of dissipative devices in the links
Resorting to prefabrication, also for the concrete elements
Use of rigid / semi-rigid link-to-side-column connections
Standard design methods and optimized solutions are necessary for the daily design of such hybrid systems. The HYCAD outcomes will include guidelines and worked examples to support the design and the application of the proposed innovative hybrid system.
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