Design Of Concrete Structures To Eurocode 2
Gabriel Litke
Concrete is a very strong and economical material that performs exceedingly well under compression. Its weakness lies in its capability to carry tension forces and thus has its limitations. Steel on the other hand is slightly different; it is similarly strong in both compression and tension. Combining these two materials means engineers would be able to work with a composite material that is capable of carrying both tension and compression forces.
EN 1992-1-1 deals with the rules and concepts required for designing concrete, reinforced concrete and prestressed concrete structures. There are three main stages are involved in the design of elements in these structures:
Pre-design stage involves selecting initial section sizes (e.g. reinforcement diameter), from which the minimum required cover depth could be selected to attain the required fire resistance. Although these initial estimates are likely to change throughout the design, giving considerable amount of thought at this stage is likely to save a lot of time later on.
Ultimate limit states are often more critical for concrete structures. Consequently, when design is undertaken, the ultimate limit state is designed for and then if necessary serviceability is checked for. However, element sizes ascertained in the pre-design stageusually ensure serviceability criteria are met.
If actual deflections are required, then the structure must be analysed for the serviceability limit state, using design service loads. The deflections obtained will generally be short term values and will be multiplied by a suitable factor to allow for creep effects and to give realistic long term values.
EN 1992-1-2 deals with the design of concrete structures for the accidental situation of fire exposure and is intended to be used in conjunction with EN 1992-1-1 and EN 1991-1-2. This part 1-2 only identifies differences from, or supplements to, normal temperature design. Part 1-2 of EN 1992 deals only with passive methods of fire protection. Active methods are not covered.
EN 1992-1-5 gives a general basis for the design of reinforced concrete components provided with unbonded tendons placed within or outside the concrete. In addition, it provides design rules which are mainly applicable to buildings but, does not apply to structures subjected to significant fatigue under variable loads. It does also not apply to structures with tendons temporarily ungrouted during construction.
EN 1992-1-6 provides supplementary rules to the general rules given in ENV 1992-1-1 for the design of components in building and civil engineering works in plain concrete made with normal weight aggregate.
EN 1992 Eurocode 2 applies to the design of buildings and other civil engineering works in plain, reinforced and prestressed concrete. It complies with the principles and requirements for the safety and serviceability of structures, the basis of their design and verification that are given in EN 1990: Basis of structural design. EN Eurocode 2 is concerned with the requirements for resistance, serviceability, durability and fire resistance of concrete structures.
Part 1.1 gives a general basis for the design of structures in plain, reinforced and prestressed concrete, while Part 1-2 deals with the design of concrete structures for the accidental situation of fire exposure. Part 2 gives a general basis for the design and detailing of bridges in reinforced and prestressed concrete. Finally, Part 3 covers additional rules for the design of concrete structures for the containment of liquids or granular solids and other liquid retaining structures.
This Special Issue is dedicated to the Second Generation Eurocode 2. The publication features 15 papers by members of the European Subcommittee CEN TC250/SC2 Eurocode 2 and the Spanish Mirror Group UNE CTN140/SC2 Eurocdigo 2. The papers are in English language, with Abstracts also in Spanish.
The aim of this publication is to make the transition to Eurocode 2: Design of concrete structures as easy as possible by drawing together in one place key information and commentary required for the design and detailing of typical concrete elements.
This version, updated in January 2022, has had revisions made to Chapter 10: Detailing to reflect an updated understanding of the simplified detailing rules for simply-supported beams and slabs.
*Please note that, if you purchase a hard copy, the PDF version is included in the cost and will be sent to you upon payment, as well as being available in your My Account area.
The Concrete Centre provides material, design and construction guidance. Our aim is to enable all those involved in the design, use and performance of concrete and masonry to realise the potential of these materials.
This document provides an introduction to using Eurocode 2 (EC2) for designing concrete structures. Some key points:1. EC2 is part of a family of Eurocodes that will replace existing national standards for structural design across Europe, including BS 8110 in the UK. 2. EC2 takes a statistical approach to determining design values for actions (loads) on structures using characteristic, combination, frequent and quasi-permanent values. 3. Load combinations in EC2 consider multiple variable actions and are determined based on the design situation and type of limit state being assessed.4. EC2 represents a more technical and less restrictive approach than BS 8110, aiming for more economic yet safe concrete structureRead less
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It has been an interesting and challenging journey to observe the development of 3D Printing technology in 2023. While working on various aspects of the technology, I was awarded a Fellow of the Nigerian Institution of Structural Engineers (FNIStructE). It seemed like yesterday when I wrote the Seven-and-a-half-hour open-book professional exams. The weight of the achievement dawned on me when I was personally congratulated by each of the past Presidents of the Institution. I hope this achievement is the birth of greater things to come. The ability to develop multi-story structures is one question I have been asked several times in the development phase of 3D Printing technology. I believe that this can be achieved if well-understood structural design principles are followed.
The foundation type of the building structure will be developed by following the standard/traditional approach of analyzing a soil test to determine the right depth to place a designed foundation footing and soil pressures that can withstand the building loads. I am of the view that in the future, connecting walls of simple foundation footings such as strip and pad footing will be 3D Printed. The loads and design considerations remain the same. We followed guidelines in Eurocode 2: Design of Concrete Structures-Part1-1: General rules and rules for buildings. However, the wall load should be considered concrete because the walls achieve above 50Mpa at 28 days. In most cases, the walls can be designed as unreinforced masonry walls subjected to shear and moment. Shashank and Raghunath (2014) are of the view that in some cases shear reinforcement should be considered.
We discovered that it is difficult to 3D Print a single continuous wall due to sensitivity to slenderness and this conforms to the need to stiffen the wall through the use of connected floors or roofs as specified in Eurocode 6. With the support of the 14Trees design team, we adopted a unique wall shape to solve this challenge. However, for multi-story building designs, we will use double walls and connect effectively to the walls of the building to achieve the required stiffness. As we bid 2023 goodbye, I keep thinking about the likely interesting industry topics that I will write about in 2024. I am sure that the G+1 and G+2 3d Printed building design will be one of the topics. Thank you for following my journey and reading about this exciting project and I wish everyone a prosperous 2024.
Modeling of concrete structural elements using linear analysis to extract a reasonable structural response typically involves modifying the stiffness of concrete structural elements. However, this method presents its challenges, including the following:
This article aids the structural engineer by providing a summary of the range of stiffness modifiers recommended by domestic and international publications for a variety of building components. A literature review of codes, standards, and research articles is provided, along with a brief summary of the key assumptions made in each document. Effective stiffness parameters for flexural and shear stiffness are summarized in the Table for easy comparison.
A summary of a variety of documents, which were published domestically and are typically used by structural engineers in the United States, is included below. Note that the recommendations provided in each document correlate to specific return periods or hazard events, or specific levels of applied loading. Some recommendations are independent of loading.
ACI 318-11 is referenced by the 2012 International Building Code (IBC). Sections 8.8.1 through 8.8.3 provide guidelines for effective stiffness values to be used to determine deflections under lateral loading. In general, 50% of the stiffness based on gross section properties can be utilized for any element, or stiffness can be calculated in accordance with Section 10.10.4.1. ACI 318-14 contains similar recommendations for stiffness modifiers reformatted in Section 6.6.3.
Section 10.10.4, Elastic Second Order Analysis, provides both a table of effective stiffness values independent of load level and equations to derive stiffness based on loading and member properties. Commentary Section R10.10.4.1 explains that these recommendations are based on a series of frame tests and analyses, and include an allowance for the variability of computed deflections (MacGregor and Hage, 1977).
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