reinforced concrete box girder bridge design example

Design of a Skew, Reinforced Concrete Box-Girder Bridge Model RAYMONDE. Prestressed concrete is concrete that . In circular voided decks the ratio of [depth of void] / [depth A 150-mm thick topping slab was cast over the top flange of the beams after full stressing. k1 = 0.8 (high bond bars) Hence restrained temperature stresses per C = 31 10 3 12 10 -6 = 0.372 N/mm 2. Force F to restrain temperature strain : 1 Lyang, J., Lee, D., kung, J. Worked Example | Design of RC beams for Torsion (EN 1992-1:2004) By. For instance, girder bridges support the deck slabs on which vehicles and people pass. The box girder normally comprises either prestressed concrete, structural steel, or a composite of steel and reinforced concrete. (x/d) = (2.2fyAs) / (fcubd) You can read the details below. Mc = Vcav = vcbdav (c) Structural analysis of the beam. These bridges consist of multiple precast concrete box girders that are butted against each other to form the bridge deck and A box girder bridge is a special type of bridge in that beams have to compromise girders in the shape of empty box. Act = 1000 650 / 2 = 325000 mm2 Second Moment of Area = 1000 6503 / 12 = 22.9 109 mm4, Force F to restrain temperature strain : = As / btd and ' = A's / btd The bridge has zero skew. Design compressive strength = fcd = ccfck / c, Try 32mm dia. As,min = 0.4 0.755 3.5 325000 / 500 = 687 mm2, Minimum area of longitudinal reinforcement As,min = 0.26btdfctm / fyk > 0.0013btd reinforcement @ 125c/c (0.87fy)As = (0.4fcu)bx DAVIS A 1: 2.82 scale model of a two-span, continuous, reinforced concrete box-girder bridge, which has supports skewed at 45, was constructed and tested at the University of California, Berkeley. Also the girder can be constructed in wider because of the presence of two webs and . DAF for 130kN axle = 1.16 axle load = 1.16130/3 = 50.3kN. Tensile stress due to reverse temperature difference = fL 8.35[{(1.43+0.06)(130-60-16)/130}-0.06] = 0.8 4.7 = 3.8 N/mm2 LRFD Design Examples. Design of T-beam a) Outer girder. ii) Stress Limits Check stresses in the concrete and reinforcement at: 6.9 spans 21.6 m and supports a superimposed dead load G of 6 kN/m and a live load Q of 20 kN/m (excluding self-weight). (Ref:"Concrete bridge engineering:performance and advances" by R.J.Cope). Publication of this paper sponsored by Committee on Concrete Bridges. Crack width wk = sr,max(sm - cm) = 338 0.328 10-3 = 0.11 mm, Recommended value of wmax = 0.3 mm > 0.11 mm OK, Hence B32 bars at 125 centres are adequate for the mid span. Equating forces: Activate your 30 day free trialto continue reading. Try 32mm dia. There is a correction formula (equation 25 in clause 5.8.8.2) which allows for the stiffening effect of concrete in the tension zone. k2 = 0.5 (for bending) Ecm = 22[(fck + 8) / 10]0.3 = 22[(32 + 8) / 10]0.3 = 33.4 kN/mm2 in the direction of the principal moments. For values of x > 0.5d the use of the design stress of 0.87f y in tension is invalid, the design becomes inefficient and the failure less ductile. 0.75fy for reinforcement in tension or compression. Reinforced Concrete Deck Example to BS 5400. Determine depth 'X' to neutral axis of cracked section: Youngs Modulus for concrete for long term loading = Ec/2 = 15.5 kN/mm2 are transferred to the substructure through the girder and then to the ground. Mult = 14.7 1000 190.6 (574 - 0.416 190.6) 10-6 = 1386 kNm > 1340 OK. The prestressed concrete bridge girder shown in Fig. s = cu2(d/X - 1) = 0.0035 ( 574 / 190.6 - 1) = 0.007 > 0.00217 steel will yield. That fact justifies the suggestion made by the Commission Ill of the {ABSE that a comprehensive survey be wittan concerning this particular bridge type. The determination of the . Typically, girders for single span bridges will be placed either singly or in braced pairs spanning full length between the end supports. Fixing tolerence for reinforcement cdev = 15mm for insitu concrete Rearranging and dividing both sides by d we get: vc = (0.27 / 1.25) [100 6434 / (1000 574)]1/3 (40)1/3 = 0.77 N/mm2 FOREWORD 'The box girder is today the most widely used superstructure in conorete bridge construction. Program: Program version: V12 and higher Design checks available through the bridge modeler include: shear; flexural; flexural stress; principal stress; Comments: No mild reinforcement provision; PCI design example 9.2 bridge-modeler; bridge; design-code; complete; Overview. A full torsional design covering the ultimate and serviceability limit states is required when the equilibrium of a structure is dependent on the torsional resistance of the member. - 0.4 103 [ 130 ( 1.8 + 2.5 + 1.5 + 1.9 ) + 163 ( 0.9 + 0.75 )] 10-3 = - 508 kN Where = 1 - [0.5cu22 - c22 / {(n+1)(n+2)}] / [cu22 - cu2c2 / (n+1)] Use Grade B500B reinforcement to BS 4449. structure to withstand winds of 286 kilometres per hour (178 mph), earthquakes measuring to 8.5. on the Richter scale, and harsh sea currents. k3 = 3.4 (recommended value) From BS 5400 Pt4 Table 3 : Ec = 31 kN/mm2 for fcu = 40N/mm2 The modified value of Ec used for the crack width calculation is an intermediate value between the short and long term values (clause 4.3.2.1(b)). k = 1.0 - {[(h - 300) / (800 - 300)] (1.0 - 0.65)} = 0.755, fct,eff = fctm = 3.5 N/mm2 z = [1 - ({1.1 500 6434}/{40 1000 574})]d = 0.85d < 0.95 d z = 0.85 574 = 488mm. To determine the moment of resistance of a member at failure by limit state analysis the following assumptions are made: The deisgn formulae given in clause 5.3.2.3 of the code are based on a uniform compressive stress of 0.4fcu for concrete and stresses of 0.87fy in tension and 0.72fy in compression for steel. Reinforced Concrete Deck Design to EN 1992-2 & UK National Annex. Modular Ratio = Es / Ec = 200 / 24.65 = 8.1 Hence B32 bars at 125 centres are adequate for shear at the ends of the deck. sr,max = k3c + k1k2k4 / p,eff M = fsz = fykAsz / s = Fcz = favbXz Age of concrete at initial loading t0 = 6 days (when soffit formwork is released), h0 = 650 1 = [35 / fcm]0.7 = [35 / 48]0.7 = 0.80 2 = [35 / fcm]0.2 = [35 / 48]0.2 = 0.94, RH = [1 + 1 {(1 - RH / 100) / (0.1 h01/3)}] 2RH = [1 + 0.8 {(1 - 80 / 100) / ( 0.1 6501/3)}] 0.94 = 1.113, (fcm) = 16.8 / fcm0.5 = 16.8 / 480.5 = 2.425, (t0) = 1 / (0.1 + t00.2) = 1 / ( 0.1 + 60.2) = 0.653, 0 = RH (fcm) (t0) = 1.113 2.425 0.653 = 1.762 A bomb explosion within or near the bridge deck may cause catastrophic damage to the bridge components. By accepting, you agree to the updated privacy policy. Design Example - Washington State Department of Transportation Dead + Superimposed Dead Loading (per metre width of deck), SLS = Serviceability Limit StateULS = Ultimate Limit State, Design SLS moment = Gkj = (16.3 + 3.7) 122 / 8 = 360 kNm, Design ULS moment = (GjGkj) = [(1.35 16.3) + (1.2 3.7)] 122 / 8] = 476 kNm, Variable Actions (per metre width of deck). Nominal cover cnom = 45 + 15 = 60mm, Design for a 1 metre width of deck (unit strip) 11.1 Steel Girder Bridge (PDF) 11.1 Attachment 11A Steel Girder Bridge Detailing Examples (PDF) 11.2. curvature due to temperature strain : Maximu VEd = 0.5 1000 574 0.504 26.7 10-3 = 3857 kN >> 414 kN Voided Slab. April 26th, 2018 - Comprehensive Design Example for Prestressed Concrete P O Box 2345 11 prestressed concrete girder bridge Vortex induced vibrations of streamlined single box girder April 8th, 2018 - Vortex induced vibrations of streamlined single box girder and today?s cable supported bridge design has reached and used in Eurocode Cracks caused by higher loadings will not exist for long enough to affect corrosion. Mc/bd2 = vc av/d. Click here to review the details. A Girder is one of a superstructure. List of Reinforced Concrete Design Standards: [Show]. View example in PDF format (Design Example 2) Download example as a Mathcad Workbook (Zip) Adhesive Anchor Examples. i) Early Age (before creep has occurred) Dead + Superimposed Dead Loading (per metre width of deck), SLS = Serviceability Limit StateULS = Ultimate Limit State, Design SLS moment = (fL M) = [(1.0 16.3)+(1.2 2.4)] 122 / 8 = 345 kNm, Design ULS moment = f3 (fL M) = 1.1 [{(1.15 16.3)+(1.75 2.4)} 122 / 8] = 454 kNm, Nominal HA mid span moment = 17.5 12.02 / 8 + 33.0 12.0 / 4 = 414kNm. e = Es / Ecm = 200 / 35.2 = 5.7 Tap here to review the details. 500X2 + 41510X - 23.83106 = 0 You can download midas Civil trial version and study with it:https://hubs.ly/H0FQ60F0midas Civil is an Integrated Solution System for Bridge & Civil Engineer. The girder reactions are then applied to the pier. Minimum reduction is applied at 2d = 2 0.574 = 1.148m from support The three most common types of reinforced concrete bridge decks are : Solid Slab. The concrete strength class will need to be C40/50. The bridge has spans of 118 feet and 130 feet. Now customize the name of a clipboard to store your clips. 0.5fcu for concrete in compression with triangular stress distribution. From EN 1992-1-1 Table 3.1 : fck = 32 fcm = fck +8 = 40 Ecm = 22[(fcm) / 10]0.3 = 22 40.3 = 33.35 kN/mm2 The live load reaction is applied to the deck at the pier location. (b) Estimation of design load and actions. The design of a cast-in-place, post-tensioned concrete, multi-cell box girder bridge under combined torsion, shear, and flexure is presented in this example. Types of Reinforced Concrete Bridges. Skew decks develop twisting moments in the slab which become Hence dc = [-AsEs + {(AsEs)2 + 2bAsEsEc,effd}0.5] / bEc,eff EN 1991-1-5 Table C.1 - Coefficient of thermal expansion = 10 10-6 per C. Wai-Fah Chen and Lian Duan Boca Raton : CRC Press , 2000 2000 by CRC Press LLC Section II Superstructure design 2000 by CRC Press LLC 9 Reinforced Concrete Bridges Materials Concrete Steel Reinforcement bridge Types Slab Bridges T-Beam Bridges Box-Girder Bridges design Considerations Basic design . . [Show full abstract] concrete composite bridges when the Nevers bridge was designed, because box girders where also supposed to require more fabrication time. The concrete deck may be analysed in tension or in . 0.372 103 [150 (3.0 250 + 5.05 275) + 175 (0.3 87.5 + 1.35 116.7) - (20 0.15 6.7) - (195 1.05 260)] 10-6 = 111.5kNm, Force F to restrain temperature strain : . c = {1000 106 209 / (1.18 109 9.3)} + (0.6 2.49) = 19.1 + 1.5 = 20.6 N/mm2 (Heating temperature difference), Limiting concrete stress = k1fck For decks with skew less than 25 a simple unit reinforcement at 125mm centres: Each bridge is formed by steel girders acting compositely with a reinforced concrete deck slab. VEd = shear force due to ultimate actions. Note: Sign convention is compressive stresses are positive. The flexural failure in region (iv) is prevented by designing the beam for Mu in accordance with Clause 5.3.2.3. Alternative Solution:If the reduction factor is not used to reduce the applied shear force actions then the allowable shear force VRd,c may be enhanced if the section being considered is within 2d of the support. Modular Ratio = Es / Ec = 200 / 23.95 = 8.35 Prestressed Precast Concrete Beam Bridge Design. Maximum Dead Load V = f3 12 (1.15 16.3 + 1.75 2.4) / 2 ii) (h-x)/3 = (650 - 175) / 3 = 158 span 40 mtr. curvature due to temperature strain : These are designed on the basis that the beam and links act as a pin-jointed truss. vary over the slab and two directions have to be chosen in which the Hence Modified Ec for (345DL + 497LL) = (345 15.5 + 497 31) / 842 = 24.65 kN/mm2, Youngs Modulus for steel reinforcement = Es = 200 kN/mm2 in order to resist the applied moments Mx, My and Mxy. The box girder normally comprises prestressed concrete, structural steel, or a composite of steel and reinforced concrete. Section 6 Prestressed Concrete Bridges | Added Section 6.1, Section 6.2, and Section 6.4 to provide background information about prestressing. Note: The loading has been simplified to demonstrate the method of designing the slab (See BS EN 1991-1-1 to 1991-1-7, 1991-2 and National Annex for full design loading.). When the shear stress v is greater than svc, as given in Table 7 of the code, then links need to be designed. X = 500 6434 / (14.7 1000 1.15) = 190.6mm Modified Ec = Ec(short-term){1-0.5[Mg/(Mg+Mq)]} Weve updated our privacy policy so that we are compliant with changing global privacy regulations and to provide you with insight into the limited ways in which we use your data. Concrete stress c = M / zc + 0.6 (differential temperature effects) Short-term modulus = Ecm HA = 17.5 1.0 + 33.0 = 17.5 kN/m(udl) + 33kN(kel), 30 units HB = 30 10 / 4 per wheel = 75 kN per wheel. Interpolating values of T from EN 1991-1-5 Table B.3 for a 0.65m depth of slab with 100mm surfacing we get: Section Properties The box is typically rectangular or trapezoidal in cross-section. The span of the deck is 12.0m centre to centre of bearings. z = [1 - ({1.1fyAs}/{fcubd})]d For the singly reinforced rectangular section: Ubani Obinna. curvature due to temperature strain : (CG = position of the centre of gravity of the three 75kN wheel loads), Nominal HB moment at X = 99.4 5.3 - 75 1.8 = 392kNm, Design HA SLS moment = fL M = 1.2 414 = 497 kNm, Design HB SLS moment = fL M = 1.1 392 = 431 kNm < 497 kNm HA critical, Total Design SLS Moment (Dead + Live) = 345 + 497 = 842 kNm, Design HA ULS moment = f3 fL M = 1.1 1.5 414 = 683 kNm, Design HB ULS moment = f3 fL M = 1.1 1.3 392 = 561 kNm < 683 kNm HA loading critical, Total Design ULS Moment (Dead + Live) = 454 + 683 = 1137 kNm, Design HA SLS moment = fL M = 1.0 414 = 414 kNm, Design HB SLS moment = fL M = 1.0 392 = 392 kNm <414 kNm HA loading critical, Design SLS Moment (Dead + Live) = 345 + 414 = 759 kNm, Design HA ULS moment = f3 fL M = 1.1 1.25 414 = 569 kNm, Design HB ULS moment = f3 fL M = 1.1 1.1 392 = 474 kNm < 569 kNm HA loading critical, Design ULS Moment (Dead + Live) = 454 + 569 = 1023 kNm. Maximum HA V = 1.1 190 kN = 209 kN, Maximum HB V = f3 1.3 75 (11.426 + 9.626 + 3.626 + 1.826) / 12 Ixx = 10001983 / 3 + 8.16434(574-198)2 = 9.96109 mm4, Max compressive stress in concrete = 842106 198 / 9.96109 = 16.7 N/mm2, Allowable compressive stress = 0.5fcu = 20 N/mm2 > 16.7 OK, Tensile stress in reinforcement = 842106 (574 - 198) 8.1 / 9.96109 = 257.5 N/mm2, Allowable tensile stress = 0.75fy = 375 N/mm2 > 257.5 OK, Strain in reinforcement = 1 = 257.5 / 200000 = 0.00129, Notional surface for crack calculation = 35mm cover to reinforcement, m = 1 - [{3.8bth(a'-dc)} / {sAs(h-dc)}] [(1-Mq/Mg)10-9] The concrete strength class will need to be increased to class C40/50 (e) Flexural design (bending moment resistance) (f) Curtailment and anchorage. Ixx = 10002003 / 3 + 8.356434(574-200)2 = 10.18109 mm4>, Max compressive bending stress in concrete = 759106 200 / 10.18109 = 14.9 N/mm2 Steel strain at yield = s,yield = fyk / s / Es = 500 / 1.15 / 200000 = 0.00217 The maximum moment for the HB vehicle occurs at point X in the diagram below with the vehicle positioned as shown. Moment due to short-term actions = Mst = 640 kNm However these directions Design carry 30 units of HB load. VRd,c = 387 kN < VEd = 414 kN Fail. Maximum allowable shear force = 0.5bwdfcd 1 = 6434 / (1000 574) = 0.011 < 0.02, fck = 40 ( < Cmax = C50/60) Cl. Try 32mm dia. Let: Depth to neutral axis X = fykAs / (favbs) The results from the beams tested without shear reinforcement showed that for a constant concrete strength and longitudinal steel percentage, the relationship between the ratio of the bending moment at collapse (Mc) to the calculated ultimate flexural moment (Mu) and the ratio of shear span (av) to effective depth (d) is as shown below: The diagram has four distinct regions, each of which has a different mode of failure. 1 m (3.3 ft). Bridging the Gap Between Data Science & Engineer: Building High-Performance T How to Master Difficult Conversations at Work Leaders Guide, Be A Great Product Leader (Amplify, Oct 2019), Trillion Dollar Coach Book (Bill Campbell). a simply supported reinforced concrete deck slab using a unit strip method. MuConcrete = 0.15fcubd2 = 0.15 40 1000 5742 10-6 = 1977 kNm/m > 1366 reinforced bridges concrete. Use C32/40 concrete to BS 8500. 0.4 103 [ 150 ( 3.0 + 5.05 ) + (195 1.5) + (195 1.05)] 10-3 = 683 kN Cl. Minimum VRd,c = (vmin)bwd = 0.035k3/2fck1/2bwd = 0.035 1.593/2 401/2 1000 574 10-3 = 255 kN. Extensive tests on various steel arrangements have shown the best positions Hence B32 bars at 125 centres are adequate for the mid span. Activate your 30 day free trialto unlock unlimited reading. Hence restrained temperature stresses per C = 31 103 12 10-6 = 0.372 N/mm2, Section Properties be less than 49% of the deck sectional area. Total tensile stress in reinforcement = 232.8 + 3.8 = 237 N/mm2, Allowable tensile stress = 0.75fy = 375 N/mm2 > 237 OK. These two equations are based on a value of d'/d 0.2, which ensures a strain 0.0035 x 0.6 = 0.0021 in the compression reinforcement. BDD Chapter 11: Steel Girder Bridge (PDF) 11.1 . kc = 0.4 Interaction between bending and shear at support P1. Shear resistance of the stiffened web panel closest to the internal support P1. Combination 3 SLS Design Moment = 759 kNm (345DL + 414LL) This bridge design excel sheet contains 11 individual excel sheets which are supported with the most recent codes like ACI, AASHTO LRFD, and so on. Fundamentals of Prestressed Concrete Bridges. Nominal cover to reinforcement in deck soffit = 60mm, d = 650 - 60 -32/2 = 574 Let the shear force at failure = Vc and the nominal shear stress vc = Vc / bd then: 1000 X2 / 2 = 6.45 6434 (574 - X) 3.1.6(101)P] The following concrete deck design criteria are obtained from the typical superstructure cross section shown in Figure 2-1 and from the referenced articles and tables in the AASHTO LRFD Bridge Design Specifications (through 2002 interims). fcd = ccfck/c easily adaptable for high skew. Reinforced Concrete Deck Force F to restrain temperature strain : The deck carries a 100mm depth of surfacing, 7.2.2) than 25 then a grillage or finite element method of analysis will VRd,c = 387 kN 395 kN (2% error say OK for conservative nature of unit strip analysis). Total compressive stress in concrete = 14.9 + 1.8 = 16.7 N/mm2, Tensile stress in reinforcement = 759106 (574 - 200) 8.35 / 10.18109 = 232.8 N/mm2 Equating forces: Region (iii) fails when a flexural crack develops into a shear crack. Captured in the video, Mr. Corven goes through the key points of the manual, and provides insights for both . X = 200 mm, Second Moment of Area of cracked section: The box girders can also be constructed as precast section or composite with precast, pre-tensioned U section and an in situ concrete slab. Loads due to structures, vehicles, passengers, and etc. Determine depth 'X' to neutral axis of cracked section: Youngs Modulus for concrete for short term loading = Ec = 31 kN/mm2, Youngs Modulus for steel reinforcement = Es = 200 kN/mm2 This example illustrates the design of a two span cast-in-place post-tensioned concrete box girder bridge. View example in PDF Format (Design Example 1) Download example as a Mathcad Workbook (Zip) Cast-in-Place Flat Slab Bridge Design. The methods given in the code for checking crack widths assumes a linear elastic behaviour. VRd,c = [0.12 1.59 (100 0.011 40)1/3] 1000 574 10-3 = 387 kN ( < 414 kN Fail : see below) Maximum ULS shear force due to gr5 = 1.35 [50.3 (11.426 + 10.226 + 9.026 + 7.826 + 6.626 + 5.426)/12] = 286 kN, Maximum VEd from permanent actions = {[(1.35 16.3) + (1.2 3.7)] 12/2} - {0.574 [(1.35 16.3) + (1.2 3.7)]} = 143 kN (0.87fy)As = 0.2fcubd + (0.72fy)A's On 5th November 2022 . fy = 500N/mm2 Hence dc = [-AsEs + {(AsEs)2 + 2bAsEsEc,effd}0.5] / bEc,eff values for Mx, My and Mxy where Mxy represents the twisting moment in Cracks in concrete can be caused by: Corrosion of reinforcement is controlled by use of suitable concrete grades and providing adequate cover to the reinforcement. Check that steel will yield: Modulus of Elasticity Es = 200 kN/mm2 cc = 1.0 [see NA to Cl. The deck should also be designed to This article provides a description of the features of this type of bridge and introduces some of the structural design considerations. VRd,c = [0.24 1.59 (100 0.011 40)1/3] 1000 574 10-3 = 773 kN ( > 429 kN OK), ii) Consider a section at 2d (a = 1.148m say 1.15m) from the support (no enhancement): The load is distributed to the girders assuming the deck acts as a series of simple spans supported on the girders. Mu = 0.15fcubd2 k3 = 0.8 s = {1000 106 (574 - 209) / (1.18 109)} + (0.6 5.5) = 309 + 3 s = 312 N/mm2 < 400 OK, Crack Control: The value of z is not to be taken greater than 0.95d. For bridges with short spans the precast sections are normally voided rectangular, channel, or shape. Beam / Girder Beam or girder is that part of superstructure structure which is under bending along the span. Taking first moments of area about the neutral axis: Assuming steel yields then: Maximum VEd due to gr1a = (Q1Qk1) = 1.35 [100 (0.25 + 10.8/ 12) + (5.5 6.0)] = 188 kN, TS axles of LM1 are not fully on the deck ignore the load effects from these axles [see EN 1991-2 Clause 4.3.2(1a)], Reduction factor for axle at support = av / 2d = 0.5d / 2d = 0.25 Footway loading will not affect the unit strip loading. INA = 6434 (574 - 209)2 + 21.5 1000 2093 / (3 200) = 1.18 109 mm4 (steel units) 1 = Asl / bwd 0.02 Minimum area of reinforcement = 0.15% of bad = 0.15 1000 574 / 100 = 861 mm2/m use B12 bars at 125 centres (As = 905 mm2/m) for distribution reinforcement. Only one axle should be considered for reduced load effect (see PD 6687-2:2008 Cl. dc = [-6434 200000 + {(6434 200000)2 + 2 1000 6434 200000 33400 574}0.5] / (1000 33400) = 175mm i) Consider a section at d (a = 0.574m) from the support : Use Grade B500B reinforcement to BS 4449. Problem Statement Evaluate a six-span cast-in-place reinforced concrete highway overcrossing located in southern California for seismic retrofitting. Reinforced concrete bridges with different types of deck slab have been widely used for both road and railway bridges. The relationship between the stress and strain in the reinforcement is as shown in Figure 2 of the code with , The relationship between the stress and strain in the concrete is as shown in Figure 1 of the code with . Moment at X = 143.4 5.7 - 50.3 (2.4 + 1.2) = 636kNm, Design SLS moment characteristic combination = Qk1 = 636 < 640 kNm gr1a governs, Design ULS moment = Q1Qk1 = 1.35 636 = 859 < 864 kNm gr1a governs, Design ULS mid span moment = 476 + 0 + 864 + 0 = 1340 kNm, = 360 + 0 + 640 + 0.6 (differential temperature effects), = 1000 kNm + 0.6 (differential temperature effects), Design SLS mid span moment = 360 + 0 + 0.5 0 = 360 kNm. 9.3 [{(1.52 + 0.06) (130 - 60 - 16) / 130} - 0.06] = 5.5 N/mm2 Due to the influence of this twisting moment, the most economical 0.372 103 [ 150 ( 3.0 + 5.05 ) + (195 1.5) + (195 1.05)] 10-3 = 634.2 kN, Taking moments about centroid of section to determine required moment M to restrain Comprehensive Design Example for Prestressed Concrete (PSC) Girder Superstructure Bridge Design Step 5 Design of Superstructure Design Step 5.6 - Flexure Design Design Step 5.6.1 - Flexural stress at transfer Design Step 5.6.1.1 - Stress limits at transfer . Cracked second moment of area = As(d-dc)2 + Ec,effbdc3 / 3Es In the case of T Girder and deck slab type, the slab span in two directions since it is cast integrally with main girder and . The design formulae are also based on a maximum depth of concrete in compression of 0.5d; this ensures a strain 0.0035 in the tension reinforcement. The design rules for shear in beams are based on the results of tests carried out on beams with and without shear reinforcement. The depth to the neutral axis depends upon the reinforcement provided and is obtained by equating the forces: Mu = (0.87fy)Asz 0.0013btd = 0.0013 1000 574 = 746 > 1045 OK Disclaimer: This software and other files are intended for use by consultants working for the Bridges and Structures Bureau in their development of projects for the Iowa Department of Transportation. s = 360 106 (574 - 171) / (1.34 109) = 108 N/mm2, (sm - cm) = [108 - {0.4 3.5 (1 + 5.7 0.0407) / 0.0407}] / 200000 = 0.328 10-3 1000 X2 / 2 = 8.35 6434 (574 - X) Model LM1 is positioned 5m clear of LM3 and will be off the deck. Steel stress s = M / zs + 0.6 (differential temperature effects) The steps in the design of a reinforced concrete beam are as follows; (a) Preliminary sizing of members. Free access to premium services like Tuneln, Mubi and more. For values of d'/d > 0.2 the use of a design stress of 0.72fy in compression becomes invalid. Ecm = 35.2 kN/mm2 m = 5.7 dc = 171 mm INA = 1.34 109 mm4 c = 22.4 + 1.5 = 23.9 N/mm2 more significant with higher skew angles. Using a rectangular section as an example: We first need to determine the position of the neutral axis. Blockchain + AI + Crypto Economics Are We Creating a Code Tsunami? 6.1Cross Section of Box-Girder 6.1. The box girders have many advantages like good resistance to torsion and this because of the deck is in curved plane. Clipping is a handy way to collect important slides you want to go back to later. Minimum distribution steel = B12 @ 125 c/c longitudinally (As = 905 mm2 > 687) & B12 @ 150 c/c transversely (As = 754 mm2 > 687), Eurocode Reinforced Concrete Deck Example. Two spreadsheets for determining the elastic and plastic section properties of a composite beam comprising a steel plate girder with unstiffened flanges and a reinforced concrete deck for internal and edge beams. The dashed line is Mu/bd2 which assumes flexural failure. Region (iv) fails in flexure. c = {1000 106 175 / (1.32 109 6.0)} + (0.6 2.49) = 22.1 + 1.5 = 23.6 N/mm2 (Heating temperature difference), Limiting concrete stress = k1fck Both the Serviceability and Ultimate Limit States need to be considered. f . k1 = 0.6 Strain at level of tension reinforcement s = e(Mg+Mq)(d-dc) / (IcEs) The short term value of Ec is obtained from Table 3 which is appropriate to the live load portion of the moment (Mq). Re-working the example gives: from linear strain relationship: " Reinforced Concrete Bridges." bridge Engineering Handbook. VRd,c = [CRd,ck(1001fck)1/3]bwd If you wanted to connect longer gaps of land mass, you must connect multiple spans of rcdg bridges. The box girder bridge if not designed well may not be earthquake resistant. Maximum Dead Load V = 1.1 137.7 kN = 151 kN, Determine shear effects at distance d away from the support. The SlideShare family just got bigger. in place of the slab thickness of 215 mm. The maximum moment of resistance is obtained when x = 0.5d so substituting for x we get: Buckling verifications at internal support P1 according to vi section 10, EN 1993-1-5 At . as follows, Bridge Components Girder Bridge Deck Girder Bridges. Essentials slide in bridge construction a guide for bridge designers, Composite construction in Bridge Deck systems by Suhas Khedkar Kishore Saxena, Basic components and parts of bridge structures, Reinforced slab bridge design(AASHTO allowable stress design method), Construction Of A Viaduct/Bridge: An Overview, Influence line diagram for model arch bridge, Irresistible content for immovable prospects, How To Build Amazing Products Through Customer Feedback. together with a traffic load (LM1) udl of 5.5 kN/m2 and tandem axle load of 100kN (300kN/3m lane width). Note: Intermediate sections between mid span and the ends of the deck will have a smaller moment than at mid span and a small shear than at the ends of the deck. concrete as art. Solid slab bridge decks are most useful for small, single or multi-span bridges and are easily adaptable for high skew. The permanent load portion of the moment (Mg) has an Ec value equal to half the short term value. January 21, 2021. Precast concrete adjacent-box-girder bridges are the most prevalent box-girder system for short- and medium-span bridges (which typically span from 20 ft to 127 ft [6.1 m to 38.7 m]), especially on secondary roadways. this is critical for members in axial compression. 11.3 Complete Joint Penetration & Partial Joint Penetration Groove Welds (PDF) 11.3 Attachment 11B American Welding Society Symbols (PDF) 11.4 design of bridge su perstructures, such as slab bridges, box culverts, tee beam bridges, box girders and p restressed concrete bridges. This means that plane sections before bending remain plane after bending, and the strain at any point is proportional to its distance from the neutral axis. It will be assumed that the depth of surfacing could vary considerably as a result of future resurfacing. Lever arm z = (d - 0.5x) so substuting for x we get: An optimum inspection/repair strategy is developed for these girders that are deteriorating due to . Bridge designs in many countries have led to the development of standard precast, prestressed concrete beams that are normally designed to act compositely with a cast-in-place reinforced concrete deck slab.

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