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Viaduct over Guadalhorce River and A-92 Highway, Málaga, Spain Óscar Ramón Ramos Gutiérrez, PhD (c), Civil Eng., Head of Structures Division, APIA XXI – Louis Berger DCE, PCTCAN, Santander, Cantabria, Spain; Assoc. Prof. of Steel Structures, Cantabria Univ., Spain; Marcos J. Pantaleón Prieto, PhD, Civil Eng., President, APIA XXI – Louis Berger DCE, PCTCAN, Santander, Cantabria, Spain; Full Prof. of Steel Structures, Cantabria Univ., Spain; Guillermo Ortega Carreras, Civil Eng.; Cristina Gaite González, Civil Eng.; José Manuel Martínez García, PhD (c), Civil Eng., Structures Division, APIA XXI – Louis Berger DCE, PCTCAN, Santander, Cantabria, Spain; Rubén Magán Ocaña, Civil Eng., Owner Technical Site Manager, INECO – ADIF, Antequera, Málaga, Spain. Contact: [email protected] DOI: 10.2749/101686614X13830788505838 Keywords: post-tensioned box-girder; steel tied arch; temporary fix point; self-launching gantry; delta-shaped pier. Introduction The need for the Guadalhorce Viaduct project arises from the necessity to give way to the Antequera–Granada high-speed railway line. The bridge is located in the Guadalhorce River floodplain, and thereby requires such a large length. op C s or th Au The Guadalhorce Viaduct, built as part of the high-speed line Antequera-Peña de los Enamorados (south Spain), has a length of 2525,50 m and consists of 49 spans of 51,25 m length each. It is one of the longest bridges of its type in the country and is situated in a mediumrisk seismic zone. The superstructure consists of a continuous single-cell post-tensioned box-girder of 3,40 m depth. The main span, which crosses the A-92 Highway, is 90 m long and is reinforced by two steel tied arches. This span, along with its backward and forward spans, was resolved with a steel– concrete composite box-girder with a constant depth of 3,40 m. A point of fixity is materialized in a delta-shaped post-tensioned concrete pier located in an intermediate area of the bridge in order to meet the friction, braking, and seismic longitudinal forces induced by the large length of the viaduct. Hence, expansion joints are placed at both abutments. Span-by-span erection is being followed by means of two selflaunching formwork gantries working simultaneously, starting from each abutment, and moving toward the delta-shaped pier. Temporary fixed points were required during the erection process and set at the piers placed just before the gantry. The viaduct is currently under construction. y Abstract Fig. 1: General view of the bridge The main obstacles for the viaduct to overcome were bridging the A-92 Highway that crosses underneath one of its spans and the effects of the horizontal forces due to the large length. To resolve these issues, a steel tied arch and a post-tensioned concrete deltashaped pier were designed and incorporated into the structure (Fig. 1). The bridge has a constant slope of 2,5% in the vertical alignment, whereas the plan view shows that the spans lie inside a 3100-m radius with leftward circular alignment, followed by two clothoid alignments, and ending with a 2200-m radius rightward circular alignment. The deck houses a double-track railway platform containing 10,10-m width of ballast, service sidewalks, and several devices for the installation of the railway at both sides, resulting in a total deck width of 14 m, that is normal in the high-speed Spanish railways.1 Two section types are present in the bridge: a post-tensioned concrete box- Structural Engineering International 1/2014 girder and a steel–concrete composite box-girder, both with a constant depth of 3,40 m. Both sections are continuous throughout the entire viaduct (Fig. 2). Typical Post-Tensioned Spans The Guadalhorce Viaduct presents some singularities due to both its length (2525,50 m) and the need to have a long-length span over the A-92 Highway. Consequently, two different superstructure types may be found: one used to span the highway and another used to resolve the rest of the viaduct. The total number of spans is 49, each 51,25 m long, except for the one that crosses the highway, which has a length of 90 m. The typical span consists of a continuous single-cell post-tensioned boxgirder of 3,40 m depth. This yields a depth:length ratio of 1:15, which is common for this type of bridges.2–4 The Technical Report 105 (a) PK 301+502,50 Rail expansion device PK 304+028,00 Rail expansion device 2525,50 1269,00 E1 P1 39,00 1256,50 P29 P30 4×51,25 90,00 P25 24×51,25 P48E2 18×51,25 39,00 Fix point 15,16 15,39 A-92 Minimum clearance V = 14,18 Rio Guadalhorce (b) P28 51,25 P29 39,25 P30 90,00 51,25 39,25 P31 A-92 Minimum clearance V = 14,18 Steel-concrete composite box girder Fig. 2: Elevation view of the Guadalhorce Viaduct: (a) complete viaduct, (b) steel–concrete composite superstructure spans (Units: m) 18,40 14,00 14,00 3,40 3,40 post-tensioning arrangement consists of four families of four tendons per family. Each tendon is compounded of 27 strands of 15,2 mm diameter and the tensile strength is equal to 1860 N/ mm2. The four families follow a vertical alignment that adapts to the flexural bending moment acting on the superstructure. 5,50 5,50 Post-tensioned concrete box girder Steel concrete composite box girder 1,50 Arch Span y 1,50 The deck type used for the span over the highway, along with its backward and forward spans, is a steel–concrete composite box-girder design with a constant depth of 3,40 m measured at the axis of the bridge. The section comprises a bottom flange of 5,50 m width, sloped webs at both sides 7 m apart at the top slab, and lateral overhang flanges of 3,50 m length. The top reinforced concrete slab is 0,45 m deep at the axis, decreasing to 0,375 m when reaching the webs and 0,20 m at the tip of the overhang flanges. Double composite action has been designed at the pier section in order to guarantee the stability of the bottom flange and decrease the steel plate thickness. This kind of section has already been successfully used in other bridges.5 106 Technical Report φ1,00 14,00 17,00 max. Au th or s C op The longest span of the viaduct is resolved with two steel tied arches. The sag is 17 m long, which yields a sag:length ratio of 1:5. The position of both arches as well as their truss geometry respects the skew angle formed by the viaduct alignment and the highway, improving the aesthetics. The transversal distance between arch axes is 16 m and they comprise a 1,50 × 1,50 m2 section with slots at the sides. The truss diagonals consist of six tubular shapes per arch of 1 m diameter and 20 to 30 mm depth that creates a triangular structure. 3,40 5,50 18,40 Steel-concrete composite box girder with steel tied-arches Fig. 3: Typical sections: (a) concrete box-girder, (b) steel–concrete composite box-girder, (c) steel–concrete composite box-girder with steel tied arches (Units: m) The section is completed by two longitudinal steel ties of 1,95 m width. Placed on each side of the deck, they act as tension ties of the arch and are connected to the arch truss. Anchorage ribs are placed every 20 m at the junction between the triangular diagonals and the longitudinal ties, connecting them with the steel box-girder (Fig. 3). Piers The deck is supported by 48 reinforced concrete piers. The maximum registered height is 27 m, although the via- duct is placed in a flat valley and all the piers are of similar height. The typical pier consists of a constant elliptical section shaft, with 4,50 m transversal axis and 3 m longitudinal axis. A variable elliptical section pier cap, which progressively widens throughout the 4 m height in order to house the deck-bearing devices, is placed above the shaft. The piers that support the arches consist of two frames, located at each side of the longest span, made of two reinforced concrete shafts topped by a Structural Engineering International 1/2014 lifetime, such as thermal expansion and contraction, concrete shrinkage, and creep and braking of the train passing over the deck. Typical pier 4,50 2,50 A 1,60 A 3,00 H Once the fixity point is defined, the pier design is created by the effect of the longitudinal earthquake forces acting on the deck. In the transversal direction, as most of the piers have similar height and considering the length of the structure, each pier absorbs noticeably a proportional fraction of the force corresponding to its tributary length. 3,50 4,50 8 piles φ1,80 A-A 12,00 4,00 Bearings and Rail Expansion Devices: Monitoring 4,00 4,00 3,50 4,00 Arch pier 3,00 Deep foundations are needed for the pier. Measuring 16,5 × 21,0 × 5,0 m, each of them houses 18 drilled shafts of 1,80 m diameter spaced 4,50 m between axes (Fig. 5). 3,00 The bearing devices used on the viaduct consist of sliding bearings that incorporate a PTFE (PolyTetraFluoro Ethylene, Teflon) surface and have suitable guides that restrict the movements. Two bearing devices are placed on each abutment and pier. One of them is a free bearing allowing movement in all directions, while the other one is a guided bearing that allows movement only in the longitudinal direction to accommodate thermal expansion/contraction of the deck. 8 Piles φ1,80 y op s 8 Piles φ1,80 12,00 12,00 Au 12,00 6,30 C 8 Piles φ1,80 4,53 or 4,53 th 3,50 23,00 3,50 Fig. 4: Pier geometry: (a) typical pier, (b) arch pier (Units: m) the bridge, materialized in a deltashaped pier. It consists of two sloped post-tensioned concrete shafts joint at the basement by a horizontal beam. The two shafts (2,85 m along the longitudinal axis and 5,50 m along the transversal axis) converge at the deck creating the fixity point of the viaduct for the nonaccidental horizontal forces induced in the bridge deck during its Delta shaped pier The large length of the viaduct has led to the introduction of a fixity point, located in an intermediate area of 5 2,8 5 28,146 The foundations of the piers supporting the span over the A-92 Highway consist of 12 × 12 m2 spread footings, with 3,50 m depth. Each of them houses eight drilled shafts of 1,80 m diameter, placed along three rows spaced 4,50 m apart in both directions (Fig. 4). 2,8 5,50 5,00 Delta-Shaped Pier The monitoring system records the real gap between the abutment and the superstructure, which depends on 5,00 horizontal post-tensioned bent cap that confers transversal stiffness and provides support for the steel box-girder. The four shafts are approximately 23 m high and form a rectangular section whose dimension decreases from the basement to the top. At the top, the piers are only 4 m wide along the longitudinal axis and 3 m wide along the transversal axis, whereas at the bottom the longitudinal dimension is about 6,35 m and the transverse dimension about 4,55 m. Two rail expansion devices, with maximum opening of 1200 mm, are located at both abutments. To adjust the movement of the expansion devices, a monitoring system that continuously assesses structure integrity is installed in the bridge. It tracks movements and measures temperature of the concrete wherever sensors are embedded. 2×18 Piles φ1,80 16,50 18 Piles φ1,80 16,50 21,00 Fig. 5: Delta-shaped pier geometry (Units: m) Structural Engineering International 1/2014 Technical Report 107 782,2 782,2 782 33,9 772,3 772,2 772 31,2 762,4 762,2 762 28,5 752,6 752,2 752 25,8 742,7 742,2 742 23,1 732,8 732,2 732 20,4 723,0 722,2 722 17,7 713,1 712,2 712 15,0 703,2 702,2 702 12,3 693,4 692,2 692 683,5 682,2 9,6 26/03/13 14:30 23/08/13 14:40 Time Recorded gap (abutment-deck) (mm) 36,6 Recorded gap (abutment-deck) (mm) Temperature (°C) Viaduct over Gudalhorce River structure 2. history record (b) 26/03/13 14:30 X: time, Y: c14 «section 4. bottom slab. thermometer T17» (°C) X: time, Y: c23 «abutment E2. recorded gap. láser L2» (mm) Time 23/08/13 14:40 Expected gap (abutment-deck) Viaduct over Gudalhorce River structure 2. history record (a) 682 X: time, Y: c23 «abutment E2. recorded gap. laser L2» (mm) X: time, Y: mod02 «abutment E2. expected gap. (mm) Fig. 6: (a) Recorded movements vs. temperature at abutment two. (b) Recorded movements vs. expected movements at abutment two (Units: m) C op y The real value of the thermal expansion coefficient of concrete α used in the viaduct is 10 to 20% smaller than the usual values of the codes in force.6,7 As is well known, the presence of limestone aggregate in the concrete may lower the thermal coefficient value.6,8 or s The theoretical time-dependent movement at the gap is known by means of a step-by-step analysis model that counts the real concrete ages according to the erection procedure. The comparison of the theoretical time-dependent movement and the time-dependent term of the empirical formula (1) reveal that the real time-dependent movement is about 90% of the theoretical movement. g = gini − α·T·L + β·rhe(n, r, t)·L (1) where g, expected gap at a given time; gini, initial gap; α·T·L, movement caused by the thermal action; α, thermal expansion coefficient of concrete; T, temperature of the concrete at a given time; L, distance from abutment to the center of mass of the deck; β·rhe(n, r, t) ·L, movement caused by the timedependent action; β, long-term strain caused by shrinkage and creep of concrete; rhe(n, r, t), time evolution coefficient of shrinkage and creep (0 at the beginning; 1 at the end); n, end time of shrinkage and creep (in years); r, time when shrinkage and creep are initially considered; and t, age of concrete at the time when shrinkage and creep are initially considered (in years). Empirical formula (1) is obtained by linear correlation between the recorded gap g and the recorded temperature T and the time evolution coefficient of shrinkage and creep rhe(n, r, t). With this formula, it is possible to determine the real values of α and β coefficients for the concrete used in the deck. 108 Technical Report Au th thermal and time-dependent movements. Recorded gap–temperature graph (Fig. 6a) shows that both variables are in the same phase. The gap can be expressed in terms of the recorded temperature and a time-dependent function by means of the empirical formula (1). Recorded gap–expected gap graph (Fig. 6b) shows good correlation between both variables: employed simultaneously in the viaduct, and so two different gantry suppliers were required. For the construction of the first segment (spans located prior to the steel arch), an upper self-launching formwork is used consisting of a gantry placed above the deck, while for the second segment, a lower selflaunching formwork is used and the gantry is placed below the deck. Temporary shoring towers will be installed for the assembling of the steel tied arch. The composite deck segments, previously assembled at the worksite, will be erected by cranes and supported by the towers. Temporary Longitudinal Fix Points Construction Procedure The spans of the entire bridge, except for the one over the A-92 Highway, will be assembled by means of a selflaunching formwork gantry, as per the sequence described below: • Construction of substructure components (piers and abutments). • Installation and assembly of the auxiliary equipment for the deck construction (self-launching formwork). • Casting of concrete deck in subsequent phases; construction to begin from the abutments and advance toward the fixity point. • Finishes: superstructure (ballast, sleepers, rails, culverts, parapets, barriers, etc.). To fulfill the construction deadline, two self-launching formwork gantries are Temporary fix points are needed during the construction stage in order to absorb the longitudinal effects until the connection between all the components and the delta-shaped pier takes place. The usual way of controlling these effects consists of fixing the deck to the abutment during the construction stage. However, placing the temporary fix point at the abutment in this long viaduct could lead to high relative movements during the concrete hardening between the previous and the currently cast span. It was then decided that the temporary fix points would be placed in the pier(s) of the previous cast spans. To this purpose, the actions considered during each construction stage Structural Engineering International 1/2014 to be acting on the piers, apart from the self-weight of the components, are the first-order longitudinal accidental eccentricity at the pier head, longitudinal force due to friction of the sliding bearings, second-order effects, superimposed deformations due to thermal and shrinkage/creep effects, and earthquake forces assuming a tenyear return period. structures embedded on the deck and the pier. The sizes of the steel structures have been determined in accordance to the maximum longitudinal force that acts on the pier. The longitudinal lock force acting on the deck is transmitted by means of hydraulic jacks. Structural Analysis A unique three-dimensional (3D) beam model for the entire viaduct was created, including a step-by-step analysis of each construction stage. This model allows an in-depth study of the timedependent effects, the thermal behavior between concrete and steel, and the seismic response of the structure. The special device designed to fix the pier(s) consists of a group of steel Seismic effects are considered in the model because the viaduct is situated When obtaining the natural period of vibration in the longitudinal direction, the axial flexibility of the superstructure (due to large length of the viaduct) comes into play, as well as the bending Au th or s C op y The number of temporary fixed piers in every phase depends on the superstructure length previously cast and, consequently, on the friction forces of the sliding bearings. The number of fixed piers increases from one to four, the biggest number being the worst scenario. in a medium-risk seismic zone. The seismic design was made according to the Spanish seismic code for bridges NCSP-07,9 which is quite similar to the Eurocode 8.10 The basic ground acceleration of the site is 0,09g, whereas the considered design ground acceleration was 0,113g. As per Eurocode 8, ground type C is found in the first 10 m and type A in the following 20 m. The seismic effects were determined by means of a modal response spectrum analysis, using a linear elastic model of the structure and the design spectrum given by the Spanish standard NCSP-07. Fig. 7: First longitudinal vibration mode (a) S, Mises Envelope (max abs) (Avg: 75%) +3,220e+08 +2,956e+08 +2,691e+08 +2,427e+08 +2,163e+08 +1,898e+08 +1,634e+08 +1,370e+08 +1,105e+08 +8,410e+07 +5,767e+07 +3,124e+07 +4,803e+06 Max: +3,160e+08 Elem: NUDO–1,17936 Node: 94 Min: +4,803e+06 Elem: NUDO–1,1105 Node: 350 (b) N2 Q3 Min: +4,803e+006 N1 Y X Z Max: +3,160e+008 Step: step-1 Increment 1: step time = 1,000 Primary var: S, Mises Deformed var: U Deformation scale factor: +1,000e+00 Y Z N4 N3 Q4 X Fig. 8: Shell FE-modeled connection nodes: (a) stress distribution diagrams, (b) adopted solution: double longitudinal exterior gussets Structural Engineering International 1/2014 Technical Report 109 110 Technical Report Conclusion [8] AASHTO LRFD Bridge Design Specifications, 6th ed. American Association of State Highway and Transportation; 2012. The Guadalhorce Viaduct has excelled in establishing itself as one of the longest bridges of its type in the country. A post-tensioned concrete box-girder section spans 2,5 km with a delta-shaped pier as a unique fixity point. An accurate analysis of the thermal and timedependent coefficients of the concrete could increase the length of this type of bridge, since a smaller value of concrete strain would lead to a larger maximum length of viaduct for the same rail expansion device opening. References [1] Reguero Martínez A. Tipologías de Viaductos en L.A.V. Madrid-Barcelona-Frontera Francesa. Revista de Obras Públicas 2004; 3445: 91–102. [2] Pantaleón M, Ramos OR, Ortega G, Martínez JM. Viaductos sobre río Deza y Anzo 2. V Congreso de ACHE 2011; 1: 420. [3] Manterola J, Astiz MA, Martínez A. Puentes de Ferrocarril de Alta Velocidad. Revista de Obras Públicas 1999; 3386: 43–77. op y [4] Sobrino JA, Gómez MD. Aspectos Significativos de Cálculo en el Proyecto de Puentes de Ferrocarril. Revista de Obras Públicas 2004; 3445: 7–18. s C [5] Pantaleón M, Ramos OR, Martínez JM, Ortega G. Viaducto sobre rego das Lamas. V Congreso de ACHE 2011; 1: 410. or Various finite element (FE) models by shell elements were made, covering the following variables: intersection of tubes, gap between tubes, single or double gusset, and longitudinal or transversal gussets. According to the analysis of the several solutions the double longitudinal exterior gussets was the best solution, as shown in Fig. 8. This solution allows a better distribution of stress, offers better and direct transmission of forces between [7] Eurocode 2: Design of concrete structures. European Committee for Standardization; December 2004. [9] Norma de Construcción Sismorresistente: Puentes (NCSP-07). Gobierno de España, Ministerio de Fomento; May 2007. [10] Eurocode 8: Design of Structures for Earthquake Resistance. European Committee for Standardization; December 2003. SEI Data Block Owner: ADIF, Ministerio de Fomento, Spain Contractor: ACCIONA, Spain Torres Cámara, Spain Site supervision: GETINSA, Spain GUIA, Spain Structural design: APIA XXI - Louis Berger DCE, Santander, Spain Concrete (m3): Reinforcing steel (t): Prestressing steel (t): Structural steel (t): Total cost (EUR million): 64530 14308 1280 1590 65 Service date: September 2015 (expected) [6] Instrucción de Hormigón Estructural (EHE-08). Gobierno de España, Ministerio de Fomento; July 2008. th Several options were studied when designing the connection nodes of the truss diagonals with both the longitudinal ties and the steel arches. The fatigue effects due to the railway traffic (highly important in high-speed line bridges) and the stress concentrations at the connection nodes were analyzed. the tubes and the arch and tie girder, and improves the fatigue behavior. Au stiffness of the delta-shaped pier foundation. Periods of 2,17 and 2,04 s for the longitudinal vibration modes of the left and right semi-viaduct, respectively, are obtained, which are placed in the longperiod portion of the response spectrum. As these values are quite close, the Square Root of the Sum of the Squares (SRSS) combination method is not considered accurate enough; hence the Complete Quadratic Combination (CQC) combination method was used instead.10 The deformation of the deltashaped pier foundation was studied. The maximum longitudinal seismic force obtained in the delta-shaped pier is 72 500 kN (Fig. 7). Structural Engineering International 1/2014