ACI-DAfStb
“Shear Databases” for Structural Concrete Members
Der DAfStb arbeitet seit vielen Jahren gemeinsam mit dem ACI-Subcommitee 445-D in einer gemeinsamen Gruppe an der Erstellung von allgemein anerkannten Querkraftdatenbanken. Die Spiegelung im DAfStb erfolgt durch die Arbeitsgruppe „Datenbanken Querkraft und Torsion“ unter dem Technischen Ausschuss Bemessung und Konstruktion.
Introduction
The ACI-DAfStb Shear Databases with tests on r.c.- and p.c.-beams were developed over the last 20 years by a joint group consisting of ACI Subcommittee 445-D and a working group of the DAfStb, the German Committee for Structural Concrete. It is the most comprehensive and reliable source available for researchers and code makers for unbiased evaluations of the safety and accuracy of shear design approaches. The databases have been developed and discussed in different international groups and this process resulted in clear and commonly accepted agreement on:
- Conversion factors for concrete strengths, so that only uniaxial values are declared and forwarded to the subsequent control and evaluation databases;
- Clear separation of test collection from data control and evaluation;
- Criteria for identifying tests failing in flexure and tests not fulfilling the anchorage check;
- Minimum dimensions for the web width and the beam height in two categories each;
- Criteria for the selection of tests suitable for the evaluation of design approaches;
- Procedures for assessing shear design proposals.
Content of existing Databases
There are 17 independent sets of evaluation databases (see Table 1) with different types of shear test beams published in the latest database reports DAfStb Heft 617 and DAfStb Heft 635, Volume 1 and Volume 2. All databases have been independently checked by members of the ACI-DAfStb Shear Database Group and by many cooperating researchers from all over the world, who all deserve our sincere thanks. The structure of the databases is as follows; all databases consist of three parts: the Collection Database (-DS), the Control Database (-DK) and the Evaluation Database (-A). The data processing is performed in Microsoft Excel.
The Collection Databases (-DS) contain all potentially relevant tests irrespective of possible reasons for elimination from evaluations. All available relevant data are collected for the geometry and statical system, the material properties and the test results for the load and failure location. The self weight of the beams is calculated. Furthermore, the conversions are performed for the concrete compressive and tensile strengths tested at different control specimens to mean uniaxial values for the compressive strength f1c and the concrete tensile strength f1ct.
The Control Databases (-DK) contain only tests with a complete set of essential data. The tests on slender beams with a/d ≥ 2.4 were evaluated in the Control Databases (-DK-sl) separately from the tests on non-slender beams in the Control Databases (-DK-24). In these Control Databases, the calculations are performed for the theoretical flexural failure loads, the strain/stress state at failure and the check of the anchorage at the end support. Thereby, the shear span “a” is the distance of the load F = VA to the support axis in case of beams subjected to point loads. In case of beams subjected to a distributed load along the span ℓ, the shear span is a = ℓ/4.
Based on these calculations and the fundamental data of each test, selection and sorting criteria (koni) are applied in order to filter out the reliable tests by combining results of selection and sorting criteria. Then the remaining tests are transferred to the Evaluation Databases (-A), which contains all tests suitable for comparisons with design approaches. Surveys of all tests included in the Evaluation databases have been presented in the DAfStb Hefte 617 and 635, and these databases are available to the public in Excel format for use in evaluations.
The ACI-DAfStb Shear Databases allow a consistent comparison of different shear design relationships and proposals. However, with respect to the safety level, the 5%-fractile of the model safety factors should be determined for any proposal, because a fair comparison between different proposals is only possible on this level.
In the process, several files have been generated, and an overview of the different files is provided in Table 1. More detailed information on the different databases is given in 617 and application for access for the requesting databases. Thereby, reference is made to the relevant parts in the reports DAfStb 617 and 635. The Parts 6.1, 6.2, 6.3 and 6.4 refer to non-slender beams. The Parts 2.4 to 2.6 deal with tests on beams with intermediate supports, which are published in DAfStb 635. The databases with tests on Prestressed Lightweight Concrete beams (LPC-beams) have still to be established.
Table 1: Overview of the databases and definitions of abbreviations and reference to relevant Part of DAfStb Heft 617 and 635
| Members without Stirrups (vuct) | Members with Stirrups (vsw) | |
|---|---|---|
| Reinforced Concrete (RC) | Part 2.1, Part 6.1: vuct-RC Part 2.2, Part 6.4: vuct-RC-gl Part 2.3: vuct-RC-N Part 2.4: vuct-RC-int Part 2.5: vuct-RC-int-gl Part 2.6: vuct-RC-int-gl-N |
Part 4.1, Part 6.2: vsw-RC Part 4.2: vsw-RC-gl Part 4.3: vsw-RC-N Part 6.3: vswvh-RC |
| Prestressed Concrete (PC) | Part 3: vuct-PC | Part 5: vsw-PC |
| Lightweight Concrete (LRC) | Part 7.1: vuct-LRC | Part 7.2: vsw-LRC |
| Prestressed Lightweight Concrete (LPC) | vuct-LPC | vsw-LPC |
There were several reasons to establish different databases rather than trying to establish one large database, comprising for example r.c.- and p.c.-beams without and with stirrups. Firstly, it is rather practical to work with small databases. Furthermore, apart from the geometrical data, the collection databases and control databases differ in several aspects. For example, the check for flexural failures differ considerably for r.c.- and p.c.-beams, as well as the check of the anchorage at the end support. Of course, at the level of the evaluation databases different databases can easily be merged, like for example the databases for r.c.- and p.c.-beams or the databases for slender and non-slender beams.
Attachment:
Possibilities of access, contribution and further development
The DAfStb-Hefte 617 and 635 can be ordered via www.dinmedia.de/en (search “DAfStb-Heft 635”). In consensus with the publication rules the databases published in the DAfStb-Hefte 617 and 635 can be made available as PDF- and Excel-versions after request. Please use the application form below.
In order to keep the databases updated, templates have been developed for the input of test data by researchers when they have new data to add to existing databases (see attachment below). The researcher should mark any data added or changed to a database. The ACI-DAfStb Group “Shear Databases” checks these additions and releases the updated database for use within the DAfStb and ACI. These measures aim at guaranteeing a unique and agreed upon database for all researchers.
Further the following new databases are under development:
- Database with inclined stirrups
- Database of prestressed members with inclined tendons
- Database of prestressed members with distributed loads
- Database of prestressed members with different statical systems
- Database for non-metallic reinforcement
- Torsion database
- Shear-friction database
Attachments:
Deutscher Ausschuss für Stahlbeton
Budapester Straße 31
10787 Berlin
+49 (0)30 269313-20/24
info@dafstb.de
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