Connections, Hybrid Grouted Duct Connections, And Sdcl Steel Girder
ABC-UTC RESEARCH GUIDELINEABC-UTC GUIDE FOR:REBAR HINGE POCKETCONNECTIONS, HYBRIDGROUTED DUCTCONNECTIONS, ANDSDCL STEEL GIRDERCONNECTIONSJune 2019End Date:June 6, 2019Performing Institutions:University of Nevada, RenoFlorida International UniversityName of PI(s):Dr. M. Saiid SaiidiDr. Ahmad ItaniDr. Atorod Azizinamini
TABLE OF CONTENTABSTRACT . 21.2.3.Introduction . 31.1.Background .31.2.Intended Users .41.3.Rebar Hinge Pocket Connections .71.4.Minimum Area of Rebar Hinge Section .81.5.Minimum Transverse Steel .91.6Shear Design1.7Hinge Throat Thickness .101.8Pocket Minimum Depth1.9Pocket and Socket Details.9.11.12Column To Hybrid Cap Beam Grouted Duct Connections.142.1.Joint Design .142.2.Minimum Anchorage Length for Column Longitudinal Bars .142.3.Precast Cap Beam Design .162.4.Details of Grouted Ducts .162.5.Interface Load Transfer Strength.16Simple for Dead-Load and Continuous if Liveload Steel Girder Connections . 173.1. Cap Beam Design .193.2. Deck Live Load Continuity . 213.3.Steel Blocks . 213.4.End Stiffeners . 223.5.Tie Bars. 233.6.Sheer Connectors on the Bottom Flange . 24
ABC-UTC RESEARCH GUIDELINEABSTRACTThis ABC-UTC Guide provides step-by-step design specifications that were developedfor three connections intended to be used for accelerated bridge construction. Theseconnections include rebar hinge pocket connections, hybrid grouted duct connections,and SDCL steel girder connections. The document also presents a short backgroundinformation and a concise summary of the main research study conducted towarddevelopment of this Guide. The information will be of interest to highway officials, bridgeconstruction, safety, design, and research engineers.ACKNOWLEDGMENTSThe research study resulting in development of this guideline was supported by the USDepartment of Transportation through the Accelerated Bridge Construction UniversityTransportation Center (ABC-UTC).The authors would like to thank the Research Advisory Panel members: Bijan Khaleghi,Washington State DOT; Elmer Marx, Alaska DOT&PF; Tom Ostrom, Caltrans.Several companies and organizations are thanked for various contributions to theproject: Lafarge North America Inc. for donating UHPC material, C&K JohnsonIndustries for donating corrugated metal ducts, Reno Iron Works for fabrication of steelgirders at a reduced cost, Utah Pacific Steel and NSBA for donating the steel girders,cross frames, and other steel accessories. Amir Sadeghnejad and Dr. AtorodAzizinamini, are especially thanked for development of the design guideline for SDCLsteel girder connections.2
ABC-UTC RESEARCH GUIDELINE1. INTRODUCTION1.1. BACKGROUNDBridge cast-in-place construction often leads to traffic delays, subjects highway workers and thetraveling public to increased probability of accidents, and may affect the regional economy ofthe residents. By utilizing prefabricated bridge elements, accelerated bridge construction (ABC)shortens onsite construction time. Accordingly, ABC saves time and money for the travelingpublic and enhances the work-zone safety. Due to the fact that prefabricated components arebuilt offsite and under controlled environmental conditions, ABC provides the opportunity to usenovel materials and to increase the quality and durability of the components. ABC can alsoreduce the total duration of projects as prefabrication of bridge components can be performedsimultaneously.Connections between prefabricated elements (hereby referred to as ABC connections) play acrucial role in adequate performance of ABC bridges under moderate and strong earthquakes.ABC connections have to be practical and efficiently constructible and at the same time provideclear load path under vertical and lateral loading. When used for connecting columns to theadjoining members, ABC connections must allow for the energy dissipation in the column whilemaintaining the capacity and the integrity of the structural system.Several researchers (Matsumoto et al. 2001; Restrepo et al. 2011; Tazarv and Saiidi 2014;Motaref et al. 2011; Mehrsoroush, et al. 2016; Mehraein and Saiidi 2016) have developed andinvestigated a variety of ABC connections and prefabricated elements in the past decade.These connections include but are not limited to grouted duct connections, pocket and socketconnections, mechanical bar splices, simple for dead continuous for live (SDCL) connections ofvarious configurations, and connections for partial or full precast deck panels. The primary intentof these studies was to assess the local behavior of ABC connections, formulate preliminarydesign guidelines, and build a certain level of confidence in utilizing ABC techniques.While providing invaluable information on the local behavior of ABC connections, componenttests do not provide confidence in the performance of the bridge systems when subjected to bidirectional loading. Therefore, to understand the holistic seismic behavior of ABC bridges,Comprehensive analytical and experimental investigations of a large-scale two-span steel girderbridge model incorporating six ABC connection types subjected to bi-directional horizontalearthquake motions were conducted.Findings of the aforementioned research study as well as recent related studies were utilized todevelop design guidelines and detailing recommendations for three of the six connectionsincorporated in the bridge model. The objective was to facilitate field deployment of ABCconnections. The connections included rebar hinge pocket connections, hybrid grouted ductconnections, and SDCL steel girder connections. Design provisions for SDCL steel girderconnections were developed by Amir Sadeghnejad and Dr. Atorod Azizinamini at FloridaInternational University.3
ABC-UTC RESEARCH GUIDELINE1.2. INTENDED USERSThe design procedures and detailing recommendations for the three ABC connectionspresented in this document will be of interest to highway officials, bridge construction,safety, design, and research engineers.DESIGN PROVISIONSNOTATIONSπ Depth of the concrete compressive stress block at critical section (in.)π΄π π Area of a shear connector (in.2)π΄π π Area of steel deck reinforcement in effective width of the deck (in.2)Aspπ΄π π‘ Area of one hinge hoop or spiral (in.2) Area of tie bars (in.2)Bc Column largest cross-sectional dimension (in.)ππππ Effective width of the deck (in.)c Cohesion factorπππ Structural concrete cover for deck longitudinal reinforcement (in.)ππ Clear concrete cover (in.)db Hinge bar diameter (in.)πππ Diameter of longitudinal column reinforcement (in.)π·π 1 Depth of the precast cap beam (in.)πΈπ Modulus of elasticity of the deck concrete (ksi)ππβ² Nominal compressive strength of concrete (ksi)β²πππ Nominal compressive strength of grout (cube strength) (ksi)fyππ¦πfyh Hinge bar yield strength (ksi) Expected yield stress of longitudinal column reinforcement (ksi) Nominal yield stress of the hinge reinforcement (ksi)4
ABC-UTC RESEARCH GUIDELINEfyp Steel pipe yield stress (ksi)πΉπ’ Specified minimum tensile strength of a stud shear connector (ksi)πΉπ¦π Nominal yield stress of steel blocks (ksi)πΉπ¦π Nominal yield stress of deck longitudinal reinforcing bars (ksi)πΉπ¦π‘ Nominal yield stress of the tie bars (ksi)βπ Height of steel blocks (in.)βπ Height of diaphragm (cast-in-place portion of cap beam) (in.)βπ‘ Distance of tie bars from the precast portion of the cap beam (in.)K1 Fraction of concrete strength available to resist interface shear (ksi)K2 Limiting interface shear resistance (ksi)πππ Anchored length of column longitudinal bars beyond the ducts (in.) Tension development length of the rebar hinge longitudinal bars (in.)ldπππ Development length of deck longitudinal bars (in.)πππ‘ Development length of the tie bars (in.)Lpππ‘ Plastic hinge length (in.) Length of tie bars (in.)ππ’ Superstructure demand negative moment at the face of cap beam (kip-in)ππ’ Superstructure demand positive moment at the face of cap beam (kip-in)π Number of shear connectors on the bottom flangeP Applied axial load, under the combined action of the vertical load and themaximum lateral load (kips)Pu Design axial load (kips)ππ Nominal shear resistance of a single stud shear connector (kips)ππ Factored shear resistance of one shear connector (kips)5
ABC-UTC RESEARCH GUIDELINESh Spacing of transverse hoops or spirals in equivalent CIP jointt Height of the hinge throat (in.)π‘π Thickness of the steel blocks (in.) Pipe thickness (in.)tpπ‘π Thickness of the deck (in)Ts Total tension force in rebar hinge longitudinal bars (kips)Vn Nominal shear capacity of the rebar hinge section (kips)Vu Shear demand at the hinge (kips)π€π Width of the steel block (in.)π€π Width of the cap beam (in.)π€π Width of the girderβs bottom flange (in.)Β΅ Shear friction factorΞΈ Angle between the horizontal axis of the bent cap and the pipe helicalcorrugation or lock seam (deg)ΞΈn Hinge ultimate rotationΞΈe Hinge elastic rotationΞΈp Hinge plastic rotationΞΈclos Hinge rotation corresponding to the hinge throat closureeπππ π Resistance factor Resistance factor for the shear connectors6
ABC-UTC RESEARCH GUIDELINE1.3βRebar Hinge Pocket Connections C1.0Rebar hinge is the most commonly usedcolumn hinge in the United States that canbe used either at the top or bottom ofreinforced concrete columns. Design ofthe rebar hinges has not been codified;however, Cheng et al. (2010) developed astep by step design guideline for rebarhinges based on extensive experimentaland analytical studies.Rebar hinge pocket or socket (in which thehinge element is precast or consists of arebar cage alone, respectively) connectionis a viable alternative connection foraccelerated bridge construction (ABC),which combines rebar hinge details withthose of the pocket connection. A hingeelement integrated with a precast columnis extended into a pocket left in the footing.The hinge element may be precast orconsist of a reinforcing cage that extendsfrom the column into a footing opening.The former is shown in Figure 1.1-1. Thelatter would consist of only the hingereinforcement cage as shown in Figure1.1-2 (Culmo et al. 2017). Only a fewexperimental studies have incorporatedrebar hinge pocket connections as part ofa precast bent or bridge system(Mehrsoroush et al. 2017, Mohebbi et al.2017, Shoushtari et al. 2019).Design and detailing guidelines for rebarhinge pocket and socket connections arepresented herein based on previousresearch.7
ABC-UTC RESEARCH GUIDELINEFigure 1.1-1βColumn to Footing RebarHinge Pocket Connection1.4βMinimum Area of Rebar HingeSectionFigure 1.1-2βColumn to Footing RebarHinge Socket ConnectionC1.1Eq. 1.1-1 was recommended by Cheng etThe gross area of the rebar hinge section al. (2010). It is intended to avoidshall be at least:compressive failure at the hinge.Ag ππ’0.2ππβ²(1.1-1)Pu Design axial load (kips)ππβ² (ksi)Concrete compressive strength1.5βMinimum Transverse SteelC1.2The volumetric ratio of the transverse Experimental studies by Cheng et al.reinforcement in a rebar hinge section(2010) showed that using a targetshall be determined based on momentcurvature ductility of 10 ensures ductile8
ABC-UTC RESEARCH GUIDELINEcurvature analysis of the hinge for aminimum curvature ductility of 10.behavior of the hinge specimen. TheMortensen-Saiidi method (Mortensen andSaiidi 2002) is a non-iterativeperformance-based method that wasTransverse steel can be in the form of developed to design confinementspiral or hoops and shall be extended ldreinforcement in concrete columns for ainto the column and adjoining member,specified performance level.where:ld Tension development length of therebar hinge longitudinal bars inaccordance to Article 5-11-2-1 (AASHTO,2012).For hinge section, the core concrete isessentially confined by the transversereinforcement in both the hinge and thecolumn because of the relatively smalldepth of the hinge throat. The hinge coverconcrete is confined by the columntransverse steel for the same reason.Therefore, an effective confined lateralpressure, and transverse steel ratio shouldbe used in determining the confinedconcrete properties in the momentcurvature analysis of the hinge section(Cheng et al. 2010).1.6βShear DesignC1.3The plastic shear demand at the hingeshall satisfy Eq. 1.3-1.The amount of longitudinal steel isdetermined from shear design procedure.Vu ππ VnThe design procedure is iterative and mayrequire revision of the hinge area or(1.3-1)longitudinal steel.Where:Vu Shear demand at the hinge (kips),determined based on Article 8.6.1AASHTO (2014)Vn Nominal shear capacity of rebarhinge section (kips)ππ 0.9 for shear in reinforcedUnder lateral loading, the flexural momentat the hinge section causes flexural crack.Therefore, conventional shear frictiontheory (ACI 318 2008; AASHTO 2012) thatassumes a clamping force at the entireinterface is not applicable (Cheng et al.2010). Experimental studies have shownthat cyclic loads reduce roughness in thehinge and the aggregate interlock in thecompression zone of the hinge (Cheng et9
ABC-UTC RESEARCH GUIDELINEconcreteal. 2010). Therefore, a reduced shearfriction factor is recommended in Eq. 1.3Nominal shear capacity of a two-way2, compared to the corresponding factor inhinge section shall be taken as:AASHTO (2012), which is Β΅ 0.6, forconcrete cast against hardened concreteVn Β΅(P Ts)(1.3-2) which is not intentionally roughened.where:P Applied axial load, under thecombined action of the vertical load andthe maximum lateral load (kips)Ts Total tension force in rebar hingelongitudinal bars (kips)Β΅ 0.45, shear friction factor1.7βHinge Throat ThicknessC1.4The height of the hinge throat, t, asshown in Figures 1.1-1 and 1.1-2, shallsatisfy the following criteria:The purpose of hinge throat is to allow forhinge rotation and avoid closure of the gapthat could damage the edge of the columnand increase the hinge moment. Sufficientheight of the hinge throat ensures thathinge closure is prevented (Cheng et al.2010).ΞΈn ΞΈclose(1.4-1)where:ΞΈn ΞΈe ΞΈp2)ΞΈe t Οy(1.4(1.4-3)ΞΈp Lp (Οy - Οy)4)(1.4-Lp t 0.15 fy db5)(1.4-ΞΈclose sin-1 (t / 0.5 Bc)6)(1.4-10
ABC-UTC RESEARCH GUIDELINEWhere:Lp Plastic hinge length (in.)t Height of the hinge throat (in.)fy Hinge bar yield strength (ksi)Οy Hinge section effective yieldcurvatureΟu Hinge section ultimate curvaturedb Hinge bar diameter (in.)ΞΈn Hinge ultimate rotationΞΈe Hinge elastic rotationΞΈp Hinge plastic rotationΞΈclose Hinge rotationcorresponding to the hinge throatclosureBc Column largest cross-sectionaldimension (in.)1.8βPocket Minimum DepthC1.5When the hinge element is precast, theProviding concrete cover over thedepth of a rebar hinge pocket, Hp, asreinforcement at the end of the hingeshown in Figures 1.1-1 , shall be at least: specimen is not necessary, as fillermaterial between the specimen and pocketprovides adequate protection againstHp ld cc gap (1.5-2)corrosion. However, concrete cover, whenprovided, shall be considered in Eq. 1.5-2.where:Hp Rebar hinge pocket or socketdepth (in.)ld Required tensiondevelopment length of the hingelongitudinal bars into the adjoiningmembers in accordance to Article 5-11-21 (AASHTO, 2012) (in.)cc Concrete cover over hinge11
ABC-UTC RESEARCH GUIDELINEreinforcement (Article 5-12-3 ,AASHTO2012) (in.)gap The gap between theprecast hinge element and pocket base(Article 1.7, Figure 1.1-1) (in.)When the hinge element consists of onlyextended hinge rebar cage (Figure 1.12), gap shall be taken as zero.1.9βPocket and Socket DetailsC1.6Pockets and sockets shall be constructedwith helical, lock-seam, corrugated steelpipes, conforming to ASTM A706. Thepipe thickness (tp) shall be greater than0.06 in.The 0.06 in., which was proposed byRestrepo et al. (2011), ensures theconstructability of the pipe. Furtherinformation about corrugated steel pipematerial and thickness can be found inTazarv and Saiidi (2015), and Restrepo etal. (2011).When precast hinge elements are used,high-strength, non-shrink grout shall beused as the pocket filler. The grout shallbe sufficiently fluid when rebar hingespecimen is embedded into the pocket.The compressive strength of the fillermaterial sampled and tested according toan appropriate ASTM standard shall beat least 15 percent higher than concretecompressive strength of the footing.The gap between the pocket and rebarhinge specimen shall be at least 2.0 in.but no more than 4.0 in.When the hinge element consists ofhinge rebar cage alone, concrete with acompressive strength of at least equal tothat of the footing shall be used as thesocket filler.The requirement for grout compressivestrength exceeding that of the concrete inthe footing ensures that no weak link isformed in the connection. The 15-percentoverstrength factor is due to the fact thatcompressive strength of 2.0-in cubes (asrecommended by ASTM for groutsampling) are typically more than thoseobtained from cylinder testing. Furtherinformation can be found in Tazarv andSaiidi (2015).Sufficient gap between the hingespecimen and pocket not only providesadequate construction tolerance, but alsoensures that filler material easily flowsthrough the pocket.12
ABC-UTC RESEARCH GUIDELINEC2.0A grouted duct connection includescorrugated metal ducts embedded in theadjoining precast members to anchorindividual projected column longitudinalreinforcing bars. The ducts are then filledwith high-strength non-shrink grout.Several researchers have studied bondbehavior and performance of the groutedduct connections (Matsumoto et al. 2001,Pang et al. 2008, Steuck et al. 2009,Restrepo et al. 2011). Experimentalstudies have shown that grouted ductconnections are emulative of cast-in-placeconstruction.Hybrid cap beams consist of a precast anda cast-in-place segment with the formerincorporating grouted ducts. A column tohybrid cap beam grouted duct connectionconsists of a lower precast cap beam(stage I cap beam or precast dropped capbeam) to support the girders and a cast-inplace portion (stage II cap beam) tointegrate the pier and superstructure.Column bars are extended into thecorrugated metal ducts that are groutedafterward, but extend beyond the ductsinto the CIP segment of the cap beam(Fig.2.1-1).13
ABC-UTC RESEARCH GUIDELINE2. COLUMN TO HYBRID CAP BEAM GROUTED DUCT CONNECTIONS2.1βJoint DesignJoint proportioning and joint shear designshall satisfy AASHTO (2014) 8-13.The full depth of the combined lower andupper parts of the cap beam participates inresisting the joint forces in both thelongitudinal and transverse directions.In the precast part of the cap beam, jointtransverse reinforcement shall be placedaround the ducts that anchor the columnbars.2.2βMinimum Anchorage Length forColumn Longitudinal BarsC2.2Eq. 2.2-1 is based on research byMatsumoto et al. 2008.Anchorage of the column longitudinal barsis provided through bond in a combinationof grouted ducts and CIP concrete. Thestress that is transferred through bond inthe ducts is:ππ β²π·π 1 πππ2πππ(2.2-1)Where:ππ Steel stress transferred throughbond in the ducts (ksi)π·π 1 Depth of the precast cap beam(in.)β² Nominal compressive strengthπππ14
ABC-UTC RESEARCH GUIDELINEof grout (cube strength) to betaken no greater than 7 ksi (ksi)πππ Diameter of longitudinal columnreinforcement (in.)The extension of the bars beyond theducts shall Satisfy the following equation:πππ 2πππ (ππ¦π ππ )β²πππ(2.2-2)πππ Anchored length of columnlongitudinal beyond theducts (in.)ππ¦πExpected yield stress of longitudinal columnreinforcement (ksi)ππβ² Concrete compressivestrength (ksi)Grout compressive strength in Eq. 2.2-1shall be limited to 7000 psi.2.3βPrecast Cap Beam DesignPrecast cap beam shall be designed for itsself-weight and the superstructure. Depthof the precast cap beam shall be sufficientto develop the required strength in columnbars for construction loading. Torsionalmoments due to sequential placement ofgirders shall be taken into consideration indesign of the precast cap beam.15
ABC-UTC RESEARCH GUIDELINE2.4βDetails of Grouted DuctsC2.4Semi-rigid corrugated metal (steel) ducts Semi-rigid corrugated metal ducts providespecified per ASTM A653 shall be used to sufficient anchorage between the columnanchor column bars.bar, grout, and surrounding concrete(Restrepo et al. 2011).Matsumato et al. (2001) providesbackground and details on grouting of ductconnections in terms of grout testing, groutplacement, and other grouting issues.2.5βInterface Load Transfer StrengthC2.5The load transfer strength at the columncap beam interface shall be calculated inaccordance to AASHTO (2012) 5.8.4.1-3equation, using the following parameters:Specified values for c, Β΅, K1 and K2 inequation 5.8.4.1-3 were proposed by Marshet al. (2011). It was shown that, to accountfor cyclic loading effects and the potentialfor significant cracking, the cohesion factor,c, should be ignored.c 0Β΅ 0.6K1 0.2ksiK2 0.8ksi16
ABC-UTC RESEARCH GUIDELINE3. SIMPLE FOR DEAD-LOAD AND CONTINUOUS FOR LIVE LOAD (SDCL)STEEL GIRDER CONNECTIONS3.0 Simple for Dead-load andContinuous for Live-load (SDCL) steelgirder connectionC3.0The provisions in this section apply to thedesign and detailing of connection detailover interior piers for simple for deadcontinuous for live (SDCL) steel bridgesystems. The SDCL bridge system isconstructed as simply supported undersuperstructure dead load and continuousunder superimposed dead load and liveload. The continuity is attained through aconnection detail at pier cap thataccommodates force transfer. Theconnection eliminates plate girder fieldsplices and expansion joints. This detailprovides a viable option for acceleratedbridge construction (ABC) of steel plategirder bridges.SDCL connection details for non-seismiczones has been extensively investigatedand their design and field performanceshave been established (Azizinamini 2014,Farimani et al. 2014, Javidi et al. 2014,Lampe et al. 2014, Yakel et al. 2014). Thedetails of this connection are similar tonon-seismic details with some modification(Taghinezhadbilondy 2016,Taghinezhadbilondy et al. 2018,Sadeghnejad et al. 2019).Currently, the design provisions are limitedto straight and non-skew bridges.17
ABC-UTC RESEARCH GUIDELINEFigure 1.1.1 SDCL Connection.Figure 1.1.2 Construction sequence for ABC application of SDCL.18
ABC-UTC RESEARCH GUIDELINE(b)(d)(c)(a)Figure 1.1.3 3D schematic view of SDCL Connection.3.1. CAP BEAM DESIGN3.1 Cap Beam DesignC3.1Cap beam and column joint shall be designedaccording to Section 8 of AASHTO-lrfdSeismic (2014), Section 5 of AASHTO-LRFD(2012), and Section 7 of Caltrans (2013).The cap beam in an SDCL system consists ofa precast dropped cap and a cast-in-placeportion that which creates an integralconnection. The combined section contributesto the load carrying capacity of the memberand should be designed accordingly.For ABC application, a dropped cap beam isfirst placed over precast columns. The nextstep is to place the girders with pre-toppeddeck, supported over cap beam. The last stepis to cast the concrete diaphragm andcomplete the connection, as shown in Figure3.1.2.Figure 3.1.3 shows schematic of thereinforcement that needs to be included in theconcrete diaphragm.Major elements of the connection and theircontribution to the load carrying capacity of theSDCL seismic connection, as described in thisguide are as follows:- Tension deck reinforcement and steelblocks as shown in Figure 3.1.3 (a andb) provide tension and compressionforce mechanism to form a couple thatresists the negative moment producedby the live load.19
ABC-UTC RESEARCH GUIDELINE- The tie bars, shown in Figure 3.1.3 (c),resist the tension from the verticalcomponent of the ground acceleration.- Vertical legs of the closed loop stirrups,shown in Figure 3.1.3 (d), resist themoment reversal during seismicevents.(Taghinezhadbilondy 2016,Taghinezhadbilondy et al. 2018, Sadeghnejadet al. 2019) provide more detailed informationon different components of the connectiondetail and their contribution in resistingdifferent loads applied during a seismic event.The cap beam and connection are capacityprotected elements.Research has shown that detailing of capbeam satisfying AASHTO and Caltrans jointdesign requirements is adequate for the SDCLdetail (Taghinezhadbilondy 2016,Taghinezhadbilondy et al. 2018).The dimension of the cap beam along thelength of the bridge shall satisfy the followingequations:π€π 2(πππ π‘π ππ )The dimension of cap beam along the lengthof the bridge should accommodate thedevelopment of the deck reinforcement(Section 3.2) and tie reinforcement (Section3.5) at critical sections. 2(πππ‘ π‘π ππ )Where:π€π Width of cap beam (in.)πππ Development length of decklongitudinal bars (in.) according to Article5.11.2 of AASHTO-LRFD (2012).π‘π Thickness of steel blocks (in.) basedon Section 3.3.ππ Clear cover concrete (in.) according toArticle 5.10.1 of AASHTO-LRFD (2012)πππ‘ Development length of the tie bars(in.) according to Article 5.11.2 of AASHTOLRFD (2012).20
ABC-UTC RESEARCH GUIDELINE3.2. DECK LIVE LOAD CONTINUITY REINFORCEMENTDeck live load continuity reinforcementshall be designed according to thenegative moment required at the end ofthe girder as follows:π΄π π ππ’ ππΉπ¦π (βπ π‘π πππ βπ 2)C3.2At the critical section (end of steel girder)the flexural capacity is provided by tensionin deck longitudinal reinforcement andcompression in steel blocks.Where:Azizinamini (2014) defined the desiredπ΄π π Area of steel deck reinforcement in mode of failure under negative momentsfor SDCL connection as yielding of deckeffective width of the deck (in.2)reinforcement resulting in a tensionππ’ Demand negative moment over the controlled critical section.pier (kip-in) determined according toSection 3 of AASHTO-LRFD (2012) andSection 7.2.2 of Caltrans (2013)The maximum negative moment, fromπ Flexuralresistancefactor either live load combination of AASHTOaccording to Article 5.5.4.2 of AASHTO- LRFD (2012) or 25% of the dead loadLRFD (2012) for tension-controlled applied downward on the superstructure toaccount for vertical ground acceleration asreinforced concrete sections.specified in Caltrans (2013), is used.πΉπ¦π Nominal yield stress of decklongitudinal reinforcing bars (ksi)βπ Height of diaphragm (cast-in-placeportion of cap beam) (in.)π‘π Thickness of deck (in.)πππ Structural concrete cover for decklongitudinal reinforcement (in.)βπ Height of steel blocks (in.)The longitudinal deck reinforcement shall The development of deck reinforcementbe fully developed inside diaphragm can be achieved by 90 hooked bars.(cast-in-place portion of cap beam) atcritical section.21
ABC-UTC RESEARCH GUIDELINE3.3. STEEL BLOCKSSteel block dimensions shall be proportionedas follows:π€π π€π1.7π΄π π πΉπ¦πβπ π€π πΉπ¦ππ‘π 2 ππ.Where:βπ Height of steel blocks (in.)π΄π π Area of steel deck reinforcement ineffective width of the deck (in.2)πΉπ¦π Nominal yield stress of decklongitudinal reinforcing bars (ksi)π€π C3.3Design and proportioning of steel blocksare according to non-seismic SDCLdescribed by Azizinamini (2014) andFarimani et al. (2014). An iterative processcan be used to size the steel block anddetermine the amount of deck reinforcingsteel required in the connection. Steelblocks can be welded to the bottom flangeand part of the web using full penetrationw
for three connections intended to be used for accelerated bridge construction. These connections include rebar hinge pocket connections, hybrid grouted duct connections, and SDCL steel girder connections. The document also presents a short background information and a concise summary of the main research study conducted toward
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