TG6.1 - Precast floors & floors for precast structures

Over the past decade, Task Group 6.1 has concentrated on updating design recommendations for precast prestressed hollow-core slab floors, aligning them with the latest advancements in the field. Looking ahead, the objective is to expand this focus to provide a more holistic perspective on precast floor systems. This next phase seeks to develop technical bulletins, or sections within a single bulletin, with each part addressing specific aspects of flooring relevant to different types of precast floors and flooring systems for precast structures.

A primary objective is the dissemination of knowledge through seminars, educational initiatives, and engagement with standardization bodies. The goal is for this bulletin to become a benchmark for precast and flooring systems, shaping best practices throughout the industry. Additionally, the task group will offer design and calculation examples to ensure that engineers and designers can implement these guidelines effectively. These practical resources will act as educational tools for both experienced professionals and emerging engineers, potentially with support from the Young Members Group.

Convener
Stef Maas

Co-convener
Ronald Klein-Holte

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TG6.2 - Quality control for precast concrete

The goal of Task Group 6.2 (TG6.2) is to prepare a state-of-the-art report describing the steps, procedures and rules for the quality control of precast concrete, with respect to both production and product quality, to improve the quality of prefabricated construction.

The report produced is intended to serve as a basic specification guide for plants and produced precast concrete elements, defining a program of quality control to monitor the production by measurement or by comparison to acceptable standards. The following topics will be included:

• plant quality assurance program;
• material and accessories;
• production;
• transport and erection;
• recommended testing equipment;
• quality control operations;
• maintenance.

Convener
Holger Karutz

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TG6.3 - Sustainability of structures with precast elements

Sustainability is considered to be one of the main aspects of the future of construction, thus of prefabrication as well. COM6 and PCI work in close cooperation since 2008 on issues of mutual interest, with the comparison of respective approaches and the development of common publications. PCI has produced various works dealing with the sustainability of precast structures and is currently developing a large investigation program on this subject. The fib has also developed a large amount of work on sustainability. Presently, the work regarding solely sustainability is being developed in COM7 and in TG.10.1 for the MC2020.

The first activity of TG6.3 will be the study of the most recent works developed on sustainability and in particular Life Cycle Assessment regarding structures where precast concrete elements are used. Then, the TG worked on the drafting of recommendations regarding the study and assessment of precast concrete elements and structures, with respect to sustainability. This covered all aspects regarding this kind of structures, from planning, design, execution, use, maintenance, and remedial activities, up to dismantling, reuse and recycling. This conclusion of this work of the TG was the publication of the joint PCI-fib Bulletin 88 Sustainability of precast structures.

Then, the TG moved on to develop a proposal of a multi-criteria decision-making model that can be used for the assessment of the sustainability of structures with precast elements.

At the moment, the TG is working on a roadmap of sustainability performance-based design for structures with precast elements.

Convener
Albert de la Fuente

Co-Convener
Irene Josa

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TG6.4 - Precast concrete towers for wind power generators

Wind energy production is a growing industry. The energy produced is renewable and environmentally cleaner than most production means.

Supports for the wind energy generators may be built with precast concrete elements, which can be a competitive solution compared to other structural systems.

The evolution of technology for wind energy production shows a clear need for larger wind turbines and, consequently, taller towers. Experience also shows that precast solutions are even more competitive with higher towers.

Offshore wind farms have some advantages over onshore wind farms, which explain recent investments in the area. In this case, the durability of concrete in the marine environment, compared to steel gives greater advantage to precast concrete solutions.

TG6.4 will produce a state-of-the-art report analysing and discussing the main issues related to conception, design, detailing, construction and environmental aspects of precast structural solutions.

Convener
Juan-Carlos Lancha

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TG6.5 - Precast concrete bridges

Precast concrete bridges are frequently used in almost every country. Nevertheless, while it would ppear that similar practices are generally followed, the reality is that different places and cultures follow different traditions and conventions.

The group will connect the work of both PCI and fib. PCI has developed a large amount of information and publications on precast bridges.

The group will also connect the work of both Commission 1 “Concrete Structures” and Commission 6 “Prefabrication”. Both Commissions have been working on the subject of bridges, Commission 1 has an active task group on bridges and has recently published Bulletin 32 “Guidelines for the design of footbridges”. On the other hand, Commission 6 has published a state-of-the-art report regarding precast bridges, Bulletin 23 “Precast Concrete Bridges”.

The scope of the activity of the group will be the study of the most recent work that has been developed regarding bridges with precast elements and to provide design recommendations for owners, designers, contractors and precasters. The recommendations will cover all possible aspects, including planning, design, execution, use, maintenance and remedial activities and finally demolition, reuse and recycling.

Convener
Marcello Waimberg

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TG6.6 - Retrofitting of precast seismic structures

Topics to be covered within the bulletin could be:

• lessons learned and damage observation or better damage mechanisms observed in previous earthquake and associated performance of precast buildings;
• list of typical critical or less critical vulnerabilities of this class of buildings;
• simplified assessment methodology based on different levels of complexity, from quick screening (pre- or post-damage) without drawings to quick evaluation with drawings, to more detailed analysis and ultimately numerical analysis (computer based);
• overarching retrofit strategies (e.g. drift control or local ductility, thus implying a combination of global vs. local intervention);
• scenario/flowcharts of possible techniques (presented only conceptually but with practical aspects) to fulfil/achieve the targeted retrofitted performance;
• high-level (schematic) discussion of pros and cons of each retrofit solution including cost, invasiveness, downtime and other indirect but important parameters for the owner, tenants, insurer etc.

Convener
Stefano Pampanin

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TG6.8 - Terminology for precast concrete

In fib bulletins, the terminology and language used was not uniformly understood by experts from various countries throughout the world.

The objective is to create a technical report that lists the common terminology used in the prefabrication industry along with an explanation describing the terms. There may be multiple terms used with the same definition.

Convener
Jason Krohn

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TG6.9 - Precast parking structures

Besides the traffic congestion, one of the most prevalent problems in large urban agglomerations where cars are the dominant mode of transportation, vehicles spend most of the time parked. Particularly in the central areas both challenges are interrelated, since looking for parking spaces, causes congestion in circulation.

Precast concrete is generally used in the constructions of structures and buildings facilitating urban mobility (e.g. airports, stations, bridges, etc.). Precast concrete offers important advantages: large spans by using prestressed elements, speed of erection, low environmental impact, low maintenance costs and many more.

The fib published Bulletin 74, prepared by the Commission 6, an important tool to promote the use of precast concrete. It has been written to help architects and engineers to achieve a full understanding of precast concrete building structures, the possibilities they offer and their specific design philosophy.

Despite the fact this bulletin mentions the advantages of precast concrete in parking garages several times, there is a clear need to inspire designers and architects with more examples and best practices from all over the world, considering new local needs.

The purpose of this TG is to produce a State-of-the-Art Report.

This report should encourage architects and designers to use precast (prestressed) concrete for car parking structures. The report will gather examples from all over the world showing how functional, safety and aesthetics requirements can be fulfilled by using precast concrete.

The report shows the variety of precast concrete elements that can be used for this specific type of buildings, depending on the conceptual design and the aesthetic requirements.

Convener
Pieter van der Zee

Co-Convener
Iria Doniak

Co-Convener
Larbi Sennour

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TG6.11 - Social Impact of Precast Concrete

Task Group 6.11 focuses on the social impact of precast concrete throughout the entire life cycle of precast concrete elements and structures. In addition to the economic and ecological benefits of precast concrete, it is essential to analyse the social consequences for various stakeholders, including workers, users, local communities, and society at large.

Precast concrete has the potential to optimize economic costs and mitigate environmental impacts. At the same time, it is crucial to consider social consequences. Utilizing Social Life Cycle Analysis (SLCA), this task group aims to evaluate the effects on different groups. The insights will contribute to a better understanding of how precast concrete can have both positive and negative social impacts.

The increasing adoption of precast concrete in construction necessitates a comprehensive understanding of its social implications. The members of Task Group 6.11 recognize a significant potential for positive social impact arising from the use of precast concrete. By enhancing construction efficiency, reducing disruption to local communities, and improving the quality of structures, precast concrete can contribute to better living conditions and economic opportunities. As precast construction evolves, so do the relationships and impacts on various stakeholders, highlighting the need for focused analysis and recommendations.

The primary objectives of Task Group 6.11 are:

• Analysis of social impact: Investigating the social effects of precast concrete during the construction, use, and decommissioning phases, utilizing SLCA to evaluate the impacts on various groups.
• Stakeholder engagement: Involving diverse stakeholders in the process to gather different perspectives.
• Developing recommendations: Formulating guidelines to minimize negative impacts and maximize positive social outcomes.

Convener
Mischa Falger

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TG6.12 - Precast concrete modular buildings

Currently, significant housing pressures, particularly in large touristic cities, drive up prices and force families and students to relocate to the outskirts. Simultaneously, natural disasters - exacerbated by climate change - and armed conflicts are occurring with increasing frequency across the globe, underscoring the urgent need for temporary shelters and field hospitals that can be deployed quickly. Addressing these diverse challenges in a fast, high-quality, and cost-effective manner requires a focused effort to modernize and adapt the construction industry, particularly through a renewed emphasis on concrete prefabrication combined with modularization.

The planned fib bulletin (a guide to good practice) will provide guidelines for the use of precast concrete modules to build different types of buildings, from temporary buildings for emergency situations to multi-storey buildings with different kinds of use, such as residential buildings, students’ residences, office buildings, hospitals, schools and others.

Convener
Eduardo Julio

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TG5.1 - FRP Reinforcement for concrete structures

The main objectives of TG5.1 are:

• The elaboration of design guidelines in accordance with the design format of the fib Model Code for Concrete Structures 2010 (“fib MC2010”) and Eurocode 2.
• Link with other initiatives regarding material testing and characterisation & development of standard test methods.
• Participation in the international forum in the field of advanced composite reinforcement, stimulating the use of FRP for concrete structures.
• Guidance on practical execution of concrete structures reinforced/prestressed/strengthened by FRP.

Convener
Stijn Matthys

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TG5.2 - Reinforcing steels and systems

fib TG5.2 will consider all aspects related to reinforcing steels and systems from design to manufacturing, testing and final installation, use and maintenance. It will initially focus on developing a new manual which provides guidance and rules for detailing reinforcing steel. This document is intended to provide the general principles of good detailing practice and not to act as a comprehensive detailing manual. In addition, TG5.2 will address other topics considered high priority, and will create sub-groups to work on particular subjects as needed.

Areas of interest:

• review of the reinforcing steel grades available on the market (strength, ductility, bond, fatigue, durability properties) and relevant concrete structure design codes;
• manual for reinforcing materials and systems;
• technical report on fabrication of reinforcement;
• state of the knowledge on the bond properties of reinforcing steels;
• state of the knowledge on the fatigue resistance properties of reinforcing steels.

Convener
Ladin Camci

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TG5.3 - Prestressing materials and systems

Since Eugène Freyssinet’s first of use high-strength steel wire for prestressing concrete in the late 1920s, there have been many changes in prestressing systems used around the world. Current systems bear little resemblance to many of the older methods used in the past. Designers and contractors need information regarding these historical practices and materials to evaluate existing prestressed concrete in need of repair and to determine effective strategies to extend service life and enhance performance. Further, as new technologies are developed, they are often used in some countries but not in others.

TG5.3 has established two goals:

• to develop a state-of-the-art report describing the evolution and development of prestressing systems and to identify recent innovations and advances,
• to develop a new bulletin that provides recommendations for the installation of post-tensioning systems.

Convener
Tommaso Ciccone

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TG5.4 - Recommendations for ground anchor systems

The overall motivation of TG5.4 is to establish a modern recommendation for the qualification of ground anchor systems.

The main objective of TG5.4 is to prepare a bulletin entitled “Recommendation for ground anchor systems” based on and updating earlier documents such as the “Recommendations for the design and construction of ground anchors”, 1996. The recommendations will include significant content for qualification of ground anchor systems covering prestressed permanent and temporary anchors.

Convener
Matthias Ryser

Co-Convener
Xiaomeng Wang

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TG5.5 - Cables for cable supported bridges

fib Bulletin 89, Acceptance of cable systems using prestressing steels, as an update of the previous fib Bulletin 30 was published in 2019.

The goal of TG5.5 is to work on selected individual topics related to cable systems for a further future update of Bulletin 89. The topics will be addressed one after the other and published in a few individual technical reports or recommendations before they will be included in a full revision of Bulletin 89.

Workflow and Timeline:

• Fire protection and fire testing of cables: 2020 - 2025
• Damper/damping requirements: 2022 - 2026
• Icing / ice mitigation of cables: 2026 - 2028
• Update on inspection technologies of cables
• SHMS for cable stayed bridges with post-data processing
• Illumination of stay cables
• Terrorism protection of cables

New recommendations on fire protection of stay cables is expected to be published in 2025.

Convener
Werner Brand

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TG5.10 - Inspection and monitoring of reinforced/prestressed concrete structures

Maintenance of aging infrastructure (buildings, bridges, tunnels, etc.) is a significant part of both public, and private-entities’ budgets. The worldwide infrastructure and property maintenance costs are estimated to be EUR 180 billion per year. These costs depend on industry sector, age of the assets and governmental regulations. They highly affect the financial situation of public bodies and the profitability of enterprises.

There is a need to develop a guideline document to cover state-of-the-art inspection method statements, available sensor technologies including emerging digital solutions and remote sensing (e.g. drone inspection).

The required time for the development of this guideline is estimated between two to three years. The rough and high-level schedule is suggested as follows:

• First 6 to 9 months focused on building up the team and finalize the definition of the scope and content. Both are interlinked;
• Next 12 to 18 months working on developing the content of the different chapters;
• Final 6 to 9 months to finalize the first draft, including editorial review, before its submission to the TG 5.10 and C5;
• Finally, some time is expected to engage the peer reviewers and answer questions/comments received from the TG 5.10 and C5.

Convener
Antonio Caballero

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TG5.12 - Ultra-high strength prestressing steels for post-tensioning kits and stay systems

The goal of sustainability involves a consensus among economic, environmental and social factors. Due to climate change, environmental concerns have increased in society. The construction sector is among the most active high environmental impact sectors. Emissions from building and infrastructure construction are expected to form the single largest category of consumption-based emissions for C40 cities between 2017 and 2050, producing 21% of consumption emissions. As this period is critical for reducing greenhouse gas (GHG) emissions in line with keeping global temperature rise to within 1.5ºC above pre-industrial averages, serious action is needed in this area.

According to the report Building and Infrastructure Consumption Emissions prepared by C40, Arup and the University of Leeds , material efficiency stands out as having the highest potential emission reduction impact, offering savings of 18% in cumulative emissions between 2017 and 2050. Ultra-High Strength Prestressing (UHSP) strands, namely strands with tensile strength of 2060 to 2360 MPa, has the potential to greatly reduce the quantity of steel necessary in concrete structures.

The goal of new proposed Task Group is the development of a guideline where the key aspects of introducing ultra-high strength strands at different prestressing applications (along with post-tensioning and stay cable systems) i.e. crucial material properties and risk of hydrogen induced stress corrosion failure, design recommendation, system and material testing, quality control, etc. are covered.

Convener
Behzad Manshadi

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TG5.13 - Grouting of tendons in prestressed concrete

Prestressed Concrete is a very efficient, reliable and durable form of construction. However, in the 1990’s it was discovered that grout was, in some cases, inadequate.

Major investigations followed, and new regulations and recommendations (The Concrete Society TR47, PTI, fib bulletin 20, EN 445-447) were published, representing major steps forward in materials and testing requirements.

Since then, the Concrete Society has released the technical report TR72, making the TR47 obsolete. PTI has published new issue of the M50.3 specification in 2012 and again in 2019.

In 2022, time came to re-read and review the fib bulletin 20 and to collect the current state-of-the-art on grouting of multistrand tendons. The goal of Task Group was the development of a Guide to good practice, covering the same topics as the original bulletin 20.

A first draft should be presented to Commision 5 in December 2025.

Convener
Guillermo Ramírez

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TG5.14 - Durability of post-tensioning tendons

fib Commission 5 has recently initiated a new Task group TG 5.14 to cover the Durability of Post-tensioning Tendons. The task group worked jointly with fib Commission 8 and in collaboration with the Federal Highway Administration (FHWA). The document is co-published with National Member Group partner, the Post-tensioning Institute (PTI). This effort established the initial goal to update and build upon the past work of fib Bulletin 33 Durability of Posttensioning Tendons which was published in 2005. The document has been widely referenced and valuable in establishing recommendations for durable post-tensioning systems with consideration of the application and aggressivity of the environment. This guidance included the use of the Protection Level (PL) concept and information on durable post-tensioning materials and their installation. There have been continued advances since the publication of the document, and therefore the need for an update.

The scope of work for TG 5.14 focuses on providing strategies for durable post-tensioning tendons in new structures. It includes guidance on determination of appropriate protection levels, detailing for durability, guidance on specifying components of post-tensioning systems, guidance on the installation of post-tensioning systems, and information on available monitoring methods to confirm the intended durability performance. The task group collected and reviewed international experience and examined the current guidance and specifications throughout the industry. While not a fully comprehensive list, some of the documents considered include: fib Bulletin 33 Durability of Post-tensioning Tendons, TR72 Durable bonded post-tensioned Concrete Bridge, PTI/ASBI M50.3-19 Specification for Multistrand and Grouted Post-tensioning, PTI M55.1-19 Specification for Grouting of Post-tensioned Structures, and FHWA-HIF- 20-041 Methodology for Risk Assessment of Post-Tensioning Tendons, and several current fib documents related to post-tensioning. This task group under fib Commission 5 and worked jointly with fib Commission 8. There are several related efforts, within fib and other organizations. Specifically, the significant work of WP 1.1.5 Management of Post-tensioned Bridges within fib TG 1.1 is recognized and recommended for further information relating to in-service bridges.

TG 5.14 comprised a cross-section of experts representing various roles (owners, designers, suppliers, government agencies, academics, contractors, and testing laboratories) and also representing different international perspectives. The contributions of the task group led to the updates and documentation of the state of practice. This guidance provides strategies toward ensuring durable post-tensioned concrete structures.

Convener
Gregory Hunsicker

Co-Convener
Hans-Rudolf Ganz

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