This page contains a Flash digital edition of a book.
STRUCTURES & SAFETY


Robustness test on concrete frame building A section of a corner column of a seven-storey concrete frame building was removed from the ground floor in a recent


test to examine the robustness of the building. T


he building was the European Con- crete Building Project cast in-situ concrete frame at BRE Cardington. The DETR-funded test was done to:


•examine the robustness of the building (de- signed to EC2) and enhance the confidence of engineers in this form of structure in the event of accidental damage to a column;


•gain a better understanding of the whole- building behaviour of a real structure;


•calibrate analytical modelling tools to allow better prediction of the behaviour of other complex structures;


•demonstrate the use of advanced monitor- ing techniques.


Before removing the column section, engineers installed a rig, supported by hydraulic jacks, to temporarily take the load of the column. During the test the hydraulic pressure was reduced in steps to zero, leaving the corner of the building to hang unsupported.


More than 200 sensors were installed in the building to monitor downward deflec- tion, creep deflection and cracking. The building performed extremely well – down- ward deflection was just 35 mm. The build- ing was left unsupported for almost 3 days during which creep deflection was about another 3 mm. Only minor cracking devel- oped in the slab and columns.


This test was followed by upward move- ment testing in which the hydraulic jack system lifted the corner of the building, introducing a greater load into the corner column. The building moved up 52 mm under an up-thrust of 1545kN (over twice the dead load downward), resulting in only modest cracking.


A section from the ground floor corner column of a seven-storey building has been removed to test the building’s robustness.


For further information please contact Stuart Matthews at BRE (01923 664559; fax: 01923 664786;


E-mail: matthewss@bre.co.uk).


BRIDGES


BS 5400-3:2000 Design code for steel bridges The revised design code for steel bridges, BS 5400-3:2000, has recently been re-published. Sales of this new document


were suspended by BSI in January, because of typographical errors, but since then the document has been thoroughly reviewed and corrected and is now available for use in bridge design. Implementation by Technical Approval Authorities, through the Design Manual for Roads and Bridges, is expected later this year.


he revised code con- tains extensive updat ing of many design rules (from those in the original 1982 version). In particular, the rules relating to the evaluation of lateral torsional buckling (LTB) and the restraint system associ- ated with LTB have under- gone a major revision. The intention of the new


T


LTB rules is that they are more able to reflect the actual restraint systems that are used in practice – both intermediate restraints within spans and restraints at supports – although this will inevitably involve the designer in more extensive calculation. Another major revision con- cerns the rules relating to notch toughness. These have also been amended signifi- cantly, again with the intention of reflecting better the range of circumstances that occur in practice.


The Steel Construction Institute


Design guide for composite highway bridges Steel Bridges


The Steel Construction Institute


Design guide for


composite highway bridges: Worked Examples


Steel Bridges


To help designers come to terms with the new rules, the SCI has re-issued its com- mentary on BS 5400-3 and its composite bridge design guides, all of which have been revised to the new rules.


Research Focus Issue 46 AUGUST 2001


For further information please contact David Iles, Manager Bridges, The Steel Construction Institute, (01344 623345; fax: 01344 622944; E-mail:


d.iles@steel-sci.com). 5


To purchase a copy of BS 5400-3:2000 Design code for steel bridges, please contact BSI (020 8996 9000; E-mail: info@bsi.org.uk). To purchase the SCI design aids Commentary on BS5400-3: 2000, Code of Practice for the design of steel bridges, the Design guide for composite highway bridges, and the Design guide for composite highway bridges: Worked examples, please contact the Steel Construc- tion Institute (01344 872775; E-mail:


publications@steel-sci.com.


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8