WIXLIB

JORDAHLJDA Studrails Deutsche KahneisenGesellschaft mbH

JORDAHL Shear Reinforcement Systems IntroductionFlat ceiling structures with large spans betweensupporting columns allow optimum use of factoryor warehouse buildings with a large floor space.Advantagesthe underside of the ceiling has a flatappearancereduced formwork requirementsoptimum use of spaceFig. 1: punching shear situationEven in the early days of concrete structures, theproblem of punching shear at the column headarea was already recognized (Fig. 1). Mushroomconstruction was introduced around 1900 as a wayof avoiding the arrangement with main runners anddownstand girders (Fig. 2).Only a short time later the so-called Kahn steelreinforcements (Fig. 3) were used as tensile reinforcements. These components featured upturnedwings which resisted transverse forces in theceiling support area. The inventor was Julius Kahn,who came from one of the most important familiesof architects in the USA. The efforts to market thisinnovative shear reinforcement system coincidedwith the invention of the anchor rail and laid thefoundations on which the company “DeutscheKahneisen Gesellschaft JORDAHL & Co.” wasfounded. This dedication of the Kahn brothers tofind solutions to the problem of concrete reinforcement motivated us to add the JDA studrails to ourproduct range.With the aid of conventional methods it is oftennot possible to achieve thin ceilings, wide spansbetween supporting columns or large ceilingbreakthroughs close to the supporting columnheads (Fig. 4). As an alternative, Andrä et al. havedeveloped a solution in which the area at risk ofpunching shear is dowelled using dowel strips.This solution was developed further to producepunching shear reinforcements known as studrails, which are made from reinforcing steel andeach have 2 swaged heads (Fig. 5). Following theintroduction of DIN 1045-1:2001, a fundamentalreworking of the approval process became necessary. The current approval Z-15.1-214 correspondsto the latest state of knowledge and is successfullyapplied in several areas.2Fig. 2: mushroom constructionFig. 3: “Kahn” steel reinforcementsFig. 4: flat ceiling with stirrups and bent-up rebarFig. 5: JDA studrail with double-headed anchors

JDA StudrailsJDA studrails transfer high transverse forces andare ideal not only for flat ceiling structures withlow formwork and reinforcement requirements,but also in order to optimise space usage. Theresistance to punching shear failure can thus beincreased by 90 % in comparison to ceiling slabswithout punching shear reinforcement.The JORDAHL JDA studrails are made of doubleheaded anchors which are connected by a perforated connecting strip. The double-headed anchorssecure the transition between punching shear andtransverse load-bearing capacity.Technical InformationJORDAHL JDA studrails are manufactured according to the particular static requirements. Thedouble-headed anchors are available in the following sizes: dA 10, 12, 14, 16, 20 and 25 mm. Thehead diameter dk is always equivalent to 3-timesthe shaft diameter dA. This ensures slip-free anchoring of the compression area and tensile area. dk dAhkAdvantagesgeneral technical approval granted for static anddynamic loads (approval no.: Z-15.1-214)for concrete strengths ranging from C20/25to C50/60design according to the partial safety factorapproach used in Europeseparate partial safety factors for dead(γ 1.35) and imposed loads (γ 1.5)asymmetrical load applications are accuratelytaken into account for all support positionsdefined transition between punching shear andtransverse load-bearing capacity1.9-times increase in load-bearing capacitycompared to ceiling slabs without punchingshear reinforcementsuitable for flat slabs from a slab thicknessof 18 cmsimplified arrangement of the connecting stripsthrough arrangement of standard elements in a rowreduced formwork requirementsfast and easy installationcan be installed from above or from belowthe underside of slab has a flat appearanceoptimum use of spacefast and flexible delivery timesintuitive and user-friendly softwareMaterialThe double-headed anchors are made of BSt 500 Ssteel, and the perforated connecting strip is alsomade of structural steel.Elementsdouble-headed anchorcontinuous elementsstandard elements3

JORDAHL Shear Reinforcement Systems JDA Software* – Version 3.1JDA SoftwareIn order to calculate the required JDA studrails,JORDAHL Shear Reinforcement Systems can provideyou with intuitive and user-friendly calculation software. The software is based on the general technicalapproval no. Z-15.1-214 and DIN 1045-01 (edition08/2008).SettingsVia Options / Settings users can define how theresults of the calculations are determined:split standard stripsoptimised continuous strips oroptimised non-split stripsAdvantagesthe most cost-effective solution is displayed firstfast and clearly laid out input of load templatesall entries are displayed on a single pagesimple entry and structuring of projectsprintout of a verifiable structural calculationcalculation of the load scenario in an earthquake3D-view of the supportinteractive insertion of edgesinfluence of entered data is immediately visibleand understandableCutoutsSupport Type3D Viewinner, edge and corner supportsends of walls and inner cornersof wallslong supports(length ratio 1:2)Main Input WindowThis window is displayed when the program islaunched. All of the input fields are pre-filled withthe default settings. Any number of additional itemscan be added.Degree of ReinforcementSeparate entry of the degree of reinforcement in the x and y directions fordetermination of the average degree ofreinforcement ρreinforcing barsreinforcement mesh with database ofthe most commonly used mesh types4the effectiveness of the cutout is checkedautomatically (distance ‹ 6d from the edge ofthe support)cutouts can be easily inserted or moved at theclick of a mousethe program automatically detects overlappingcutoutsmanual entry of lengths to be subtracted forcritical circular sectionsdirect correction of measured values withinthe drawingthe locations of the cutouts are included onthe printout of the resultsLoad IncreaseThe fixed value β (LoadAmplification Factor) can bedetermined. The followingcan be chosen:DIN 1045-1Approval Z-15.1-214Booklet 525EarthquakeThe minimum degree of reinforcement for transverseforces is calculated in accordance with DIN 4149,and detailed and easy to follow proof is provided.

ResultThe presentation of the punching shear area inthe plan view and the cross-sectional view provides an immediate overview of the arrangementof the JDA elements.Advantages:the results printouts have been developed byinspecting structural engineersinterim results, final results and proofs can befollowed and understood very easily (punchingshear, earthquake and bond proof)graphical results can be transmitted as a*.DXF fileParts List / Ordering List / Invitation to Tender FormAll calculated items can be added to the parts list,which can also be called up as an ordering list. Inaddition, an invitation to tender form is automatically generated. Export as an *.XLS file or as a *.PDF file.Results PreviewThe preview is identical to the final results printout.All of the entered data can be checked at a glance.Can be exported as a *.JPG file, as a *.PDF file orvia the Windows clipboard.Bond ProofManual ArrangementThe load-bearing capacity of the assembly gratingsupports and shear grating supports can be calculated. The bond proof is carried out cost-effectivelytaking into account the double-headed anchorsand grating supports (expert report from RWTHAachen). The provided output is a meaningfulprintout of the results.JDA elements can be moved manually at the click ofa mouse.* The JDA Software is currently available in German only – theEnglish version will be released at the beginning of 2011.5

JORDAHL Shear Reinforcement Systems Schematic Layout 3,5dedge of the anchor-reinforcedslab area 1,7dat least 2 anchorsper element row inthe area C1,0dAAIsArea DArea CSupportcolumnArea DArea Cthe area C may be increased to 1.125dfor standard elementsSection A - A"installation from below"connecting strip below the lowerreinforcement layer"installation from above"connecting strip above the upperreinforcement layerCohdCu 0,75d 0,75d 0,75d 0,35d 0,5dIsCoEffectiveDepthhdhACu6h:d:c o:c u:h A:l s:Ceiling ThicknessEffective DepthUpper Concrete CoverLower Concrete CoverAnchor HeightStrip-reinforced Area

Layout in PracticePositioning of the JDA Reinforcing ElementsAlignment of the Strip Overhang to the Edge ofthe Supporting ColumnFor site-placed concrete ceilings we recommendinstalling the JDA elements from above. They canbe positioned after completion of the entirereinforcement assembly.It is possible to check the position of the JDAelements and to correct them as required.Safe Height PositioningConcreting the CeilingThe double-headed anchors extend through thereinforcement layers.After alignment of the JDA elements the slab canbe concreted.7

JORDAHL Shear Reinforcement Systems Installation in Site-placed ConcreteThe JDA elements can be inserted in site-placedconcrete optionally with the strips facing either upor down. In all cases the heads of the JDA anchorsmust extend through both layers of the bendingreinforcement.as far as the upper reinforcement layer (refer to thegeneral technical approval no. 15.1-214). All of theanchors used in the punching shear area of a supporting column must have the same diameter.Pre-assembly with JDA-Q Installation Aids1) Installation from above:If the JDA reinforcing elements are arrangedparallel to the upper reinforcement layer thenthe JDA-Q installation aid should be used andfastened with cotter pins.JDA-Q assembly aidLayoutThe reinforcing elements should be positionedin accordance with the planning requirements. Ifasymmetrical elements are used then the sectionmarked in blue must be positioned facing thesupport.The first strip protrusion is positioned flush againstthe edge of the support. If several standard elements are arranged in a row then the strips mustjoin up flush.marked in blue2) Installation from below:JDA-Q installation aids can also be used here inorder to improve the stability of the elements.The AH-DA spacers must be used in order toachieve the required concrete cover.JDA-Q assembly aidjoint between stripsfirst section ismarked in blueNotePrior to installation, please compare the anchordiameters, anchor spacing and anchor height withthe specifications in the formwork and reinforcement plans: the lower anchor heads must reachat least as far as the lower edge of the lowest reinforcement layer, the upper anchor heads at least8AH-DA SpacersSuitable AH-DA spacers must be used for theinstallation of the JDA elements on the formwork.JORDAHL offers spacers for concrete covers of15, 20, 25, 30 and 35 mm.