# Introduction a) General Concept arge bridge with long span and vertical clearance for navigation is required in some places. Prestressed concrete girder bridge is constructed where river is deep and more navigation clearance is required. Post tensioned box girder is the latest system for long span bridge for which modern construction technologies as well as huge construction fund are required. The box girder normally comprises either prestressed concrete, structural steel, or a composite of steel and reinforced concrete. The box is typically rectangular or trapezoidal in cross-section. Box girder bridges are commonly used for highway flyovers and for modern elevated structures of light rail transport. Although normally the box girder bridge is a form of beam bridge, box girders may also be used on cable-stayed bridges and other forms. This study is carried out with the intension of finding some other alternating as can be used as compatible to post tensioned box Girder Bridge. # b) Objective of the Study The objective of the study is to analysis of a pseudo box girder bridge of a 750m long multiple span (50m each span) using on 2 lane highway. pseudo box section as can be used for long span bridge. # d) Approach of the Study The approach of structural analysis is made by STAAD pro 2006, which is based on numerical finite element grid analysis theory. The study selected suitable section of inverted-T girders of two different lengths of 28m and 22m long which are to be applied for making continuous simply supported 750m long bridge. # II. # Modeling and Analysis # a) Introduction The bridge was analyzed as considering simply supported multi -span RCC deck slab supported on pre-stressed post tensioned concrete inverted-T girder. The bridge length is 750m comprising of 15 number spans (50m each). The bridge is analyzed as continuous multiple spans with pre-stress concrete inverse-T girder. Fixed permanent loading were analyzed to find out the inflection points. The change of inflection point was determined by different live load combinations. STAAD-pro software and AASHTO-2003 were used as design tools for numerical grid analysis and loading criteria respectively. # Results and Discussion Structural analysis of 750m continuous girder has been performed by using STAAD pro 2006 to find out inflection points for splicing which deals with the finite element analysis. We have compared the analysis result of single inverted-T girder, transverse box section and longitudinal box section to find out the depth and thickness of box Girder Bridge for different loadings to join the girder successfully at site. After analysis using STAAD Pro and checking deflection for different sections, finally we can conclude that different sections can be used for making continuous span by the technique of splicing at the erection site. # Relation of Permanent Loading and Inflection Points G-1 m Z-1 m G-2 m Z-2 m G-3 m Z-3 m G-4 m Z-4 m G-5 m Z-5 m G-6 m Z-6 m G- The inflection point due to self weight and superimposed dead load was checked by different bridge live load cases. After doing the analysis for different load cases, we found that inflection points were varied due to different loading position. The variation of changed the location of inflection point. From the above findings the bending moment of bridge is reduced gradually by finite element plate analysis. If we use false box technique then we get the reducing bending stress benefit and reduced bending stress can give reduce bending moment which gives the lighter section. For this reason, deflection due to dead load is small and the live load deflection is reduced by pre-stressing of cross girder. The pseudo box (false box) and splicing technique can be effectively practiced in the world where the box girder is most costly. Considering the socio-economic condition this technique for bridge construction is economic. # c) Merits of Pseudo Box Bridge Using Inverted-T Girder and Spliced Technique There are two types of benefit using splice and pseudo box girder. These are i. Construction Benefit Where scaffolding for long time is not permitted then pseudo Box Bridge and splicing technique can be used for construction of bridges which is less time consuming at site work. That's why less number of workers will be required. Spliced girder segments are smaller than a full girder having a length of 50m. Also handling stress of the inverted-T girder is small than the actual box section, which can be transported easily from the factory to site and also easier to erect to their final location. We can reduce traffic hazards during the construction. # ii. Structural Benefit To tell about the structural benefits about splicing technique at first we can highlight about the section of the girder. For false box technique bending stress is reduced, by the reduction of bending stress the bending moment is also reduced. Reduced bending moment can give reduced section which is lighter. For this reason, deflection due to dead load is small and the live load deflection is reduced by pre-stressing of cross girder. iii. Demerits of Pseudo Box Bridge Using Inverted-T Girder and Spliced Technique Principle demerits of using continuous girder by inverted-T girder and splicing technique are given below-? We assumed all supports are not allowed to be settled. This is uncertain and need to be researched more about soil settlement. ? Experienced and skilled workers are needed but not available in our country. ? Analysis should be done carefully to detect the inverted-T section and spliced zone. ? As it is post-tensioned pre-stressing method accuracy must be maintained. IV. # Conclusion The analysis of 750m continuous girder has been performed for two lanes 15 spans of 50m each. Objective is the beneficial using of pre-cast girder for long span bridges by pre-stressed pseudo Box Bridge using inverted-T girder and splicing technique. This analysis is done only for the vertical loadings. Analysis is fully performed by the STAADpro 2006 software to find out the moment, shear, and deflection of the structure specially the inflection zone for joining the inverted-T girders actually. With some limitations pre-stressed pseudo box using inverted-T girder and splicing technique can be applied in practical field. This technique for bridge and flyover construction is more economic and less time consuming. We hope that for our country pseudo box using inverted-T girder and splicing technique will be applied and practiced. To get the benefits both construction and structural this technique will be helpful. Bangladesh is a land of river, agricultural and flood affected country. Navigation clearance and hydraulic criteria (100year flood discharge) must be counted. That's why this technique should be practiced by the engineers. 2![Fig 2 : Typical Inflection Point Diagram](image-2.png "Fig 2 :") 1![Figure 1 : Section of inverse-T girder](image-3.png "Figure 1 :") 1BeamBeam resultsMoments (max)ShearInflection point(kN-m)(kN)(m) from leftsupportLeftMid pointRightLeftMidRight??..supportsupportsupportsupportG14698.32 -2349.1494698.32563.7960.001563.7910.10210.5739.43G24698.28 -2349.1164698.36563.793 -0.002 563.7920.10210.5739.43G34698.27 -2349.1394698.33563.794 -0.001 563.7950.10210.5739.43Table 2 : Combination-1 (SW+SDL) for Interior GirderBeamBeam resultsMoments (max)ShearDeflectionInflection point(kN-m)(kN)(Max.)(m) from left(m)supportLeft nodeMid point Right nodeLeftMidRight??..supportsupportG14339.979-2169.9824339.951520.796 0.001-520.7950.09410.5739.43G24339.949-2169.9524339.945520.793 -0.001 -520.7930.09410.5739.43G34339.938-2169.9724339.965520.794 -0.001 -520.7950.09410.5739.43 3Deflection(Max.)(m)Year 2014BeamBeam resultsEMoments (max)ShearDeflectionInflection(kN-m)(kN)(Max.)point (m)(m)from leftsupportLeft nodeMid pointRight nodeLeftMidRight??..supportsupportG15167.067-2833.5225167.038600.046-39.999-600.0450.11910.78 39.22G25167.031-2833.4855167.028600.043-40.002-600.0430.11910.70 39.22G35167.020-2833.5095167.050600.044-40.001-600.0450.11910.78 39.22Table 4 : Combination-3 self weight (SW) + Superimposed dead load (SDL) + Lane Load (UDL)+ Concentrated Load in Edge Support of the BridgeBeamBeam resultsMoments (max)ShearDeflectionInflection(kN-m)(kN)(Max.)point (m)(m)from leftsupportLeft nodeMid pointRight nodeLeftMidRight??..supportsupportG14667.065-2333.5224667.035560.0460.001560.0450.10410.57 39.43G24667.032-2333.4894667.030560.043-0.002560.0560.10410.57 39.43G34667.021-2333.5124667.052560.044-0.001560.0620.10410.57 39.43Combination-2 self weight (SW) + Superimposed dead load (SDL) + Lane Load (UDL) + Concentrated Load in Mid Support of the Bridge 5BeamBeam resultsMoments (max)ShearInflection point(kN-m)(kN)(m) from leftsupportLeft node Mid pointRightLeftMidRight??..nodesupportsupportG15311.783-5380.629 538.668 -21.377642.010.088 10.14 37.952154.362G25380.639-5434.46643.930 -17.411 583.0210.170 10.15 40.043639.122G35434.402-5434.53583.03322.988583.110.087 12.16 39.892140.849 6Deflection(max)(m)BeamBeam resultsMoments (max)ShearDeflectionInflection(kN-m)(kN)(max)point (m) from(m)left supportLeft nodeMid pointRight nodeLeftMidRight??..supportsupportG15669.964-3246.0135931.432639.779-21.562658.110.13510.9738.97G25931.422-3.2655277.88658.076-3.265578.410.15211.1240.08G35277.897-2180.1435277.900578.34418.299578.520.09111.8439.79Table 7 : Combination-6 self weight (SW) + Superimposed dead load (SDL) + Lane load (UDL)+ HS 20-44 Truck Loading at Center of All SpanBeamBeam resultsMoments (max)ShearDeflectionInflection(kN-m)(kN)(max)point (m) from(m)left supportLeft nodeMid pointRightLeftMidRight??..nodesupportsupportG15739.010-3280.8335792.63643.933-17.408 645.4510.13811.0339.20G25792.739-3267.2945643.851645.541-15.800 643.8510.13711.1239.22G35643.931-3253.8195643.92643.931-17.410 643.9310.13511.1039.13Table 8 : Combination-7 self weight (SW) + Superimposed dead load (SDL) + Lane load (UDL)+ HS 20-44 truck loading at First Support of Interior SpanBeamBeam resultsMoments (max)ShearDeflectionInflection(kN-m)(kN)(max)point (m) from(m)left supportLeft nodeMid pointRightLeftMidRight??..nodesupportsupportG15395.070-2385.6714847.661708.663-10.774633.1310.1089.9239.12G24847.678-2339.6654863.512633.028-6.713630.8910.10510.2439.16G34863.617-2392.6534863.65630.798-2.239630.9920.10910.2839.52 © 2014 Global Journals Inc. (US) Analysis of Pre-Stressed Pseudo Box Bridge using Inverted-T Girder and Splicing Technique © 2014 Global Journals Inc. (US) * Design of pre-stressed concrete structures TYLin 218 * Design of pre-stressed concrete structures TYLin 219 * Pre-stressed Concrete, A fundamental Approach EdwadGNawy 2000 Prentice Hall New Jersey 3 rd edition * Journal of Engineering Mechanics 127 1 January, 2001