Design Examples For Strut And Tie Models

fib Bulletin 61 is a continuation of fib Bulletin 16 (2002). Again the bulletin’s main objective is to demonstrate the application of the FIP Recommendations “Practical Design of Structural Concrete”, and especially to illustrate the use of strut-and-tie models to design discontinuity regions (D-regions) in concrete structures. Bulletin 61 presents 14 examples, most of which are existing structures built in recent years. Although some of the presented structures can be considered to be quite important and, in some instances, complex, the chosen examples are not intended to be exceptional. The main aim is to look at specific design aspects, by selecting D-regions of the presented structures that are designed and detailed according to the proposed design principles and specifications for the use of strut-and-tie models. Two papers at the end of the bulletin deal with the role of concrete tension fields in modelling with strut-and-tie models, and summarize the experiences gained by the Working Group in applying strut-and-tie models to the examples in the bulletin. It is hoped that fib Bulletin 61 will be of interest to engineers involved in the design of concrete structures, supporting the use of more consistent design and detailing tools such as strut-and-tie models.

"Prepared by members of ACI Subcommittee 445-1, Strut and Tie Models, for sessions at the Fall Convention in Phoenix, October 27 to November 1, 2002, and sponsored by Joint ACI-ASCE Committee 445, Shear and Torsion and ACI Committee 318-E, Shear and Torsion."

This book examines the application of strut-and-tie models (STM) for the design of structural concrete. It presents state-of-the-art information, from fundamental theories to practical engineering applications, and also provides innovative solutions for many design problems that are not otherwise achievable using the traditional methods.

"6.4.3 Example on Design of a Deep Beam with Eccentric Large Openings

The 1996 FIP Recommendations Practical Design of Structural Concretewere finally published by SETO in September 1999. They had been developed based on the 1990 CEB-FIP Model Code. The main objective of this Bulletin is now to demonstrate by practical examples the application of these recommendations, and especially to illustrate the use of strut-and-tie models for designing discontinuity regions in concrete structures. These examples represent also a continuation of the 1990 FIP Handbook on Practical Design that had been based on the former (1984) version of the recommendations. Most of the examples are recently built existing structures. Although some of them may be considered as quite important, the chosen examples are by no means exceptional. The technical report does not deal with the discussion of aesthetic or general conceptual aspects. On the contrary, the main aim is to treat particular design aspects by selecting local regions of the chosen structures, that are then designed and detailed following the design principles and specifications proposed in the 1996 FIP Recommendations mentioned above. The document is believed to be of interest to all engaged in the design of structural concrete. It hopefully supports the use of more consistent design and detailing tools like strut-and-tie models.

Structural concrete designers nowadays distinguish between B-regions (named after Bernoulli beam theory) and D-regions (D standing for ‘disturbed’). They are all familiar with B-regions, but less acquainted with the expertise required for D-regions. To design D-regions, the Strut-and-Tie Model (STM) is usually applied, a model laid down worldwide in structural codes of practice. The Stringer-Panel Model (SPM) recommended here is a companion method to the STM, with the advantage of being suitable for different load cases and reversed loading. This being so, the SPM is suitable for linear-elastic analyses where durability is a key consideration, but also suits structural design for contexts of cyclical seismic activity. Finally, this book sets out how structural engineers who prefer the STM can nevertheless apply the SPM to determine a proper strut-and-tie model.

The latest edition of this well-known book makes available to structural design engineers a wealth of practical advice on effective design of concrete structures. It covers the complete range of concrete elements and includes numerous data sheets, charts and examples to help the designer. It is fully updated in line with the relevant British Standards and Codes of Practice.