Concluding Remarks

PCI presented a s eeia award to Mexico City authorities and lo Rioboo Consulting Ungi-neers in recognition of the innovative use nf precast and prestressed concrete in the design and construction of these bridges (see July-Angusl l*)91 PCi JOl R N AI p. I0S). The completion of the bridges (see Figs, 29 and 30) marked tlie establishment of several new records in Mexico City Use of pretensioned concrete elements for bridge spans of 170 fi (52 m). Transportation inside Mexico...

Construction Highlights

The most important site work for these bridges included foundation casting precasting and driving of piles building columns and retaining walls and casting of the topping. However, even more interesting was making the connections between the precast concrete support elements, transverse cast-in-place beams, and columns this work required a high level of precision throughout the job. port activities such as the diversion of water pipes, drainage, telephone and electrical lines. Recreational...

Elevation

Plan, elevation, cross section and reinforcement details of the central beams identified as C-2. Note 1 ft 0.3048 m 1 in. 25.4 mm. Fig. 16a. Night work, showing the erection of one of the principal support spans ori the oval column supports. The precast form for the transverse beams is attached to the side of the girder. Fig. 16a. Night work, showing the erection of one of the principal support spans ori the oval column supports. The precast form for the transverse beams is attached to...

Erecting the Precast Elements

Erection of the pretensioned concrete elements was carried out during the day (Fig. 2R), except for the C-l central main elements and S-i support elements. These elements were erected at night, between i 1 00 p.m. and 4 00 a.m to avoid interfering with rush hour traffic on the Tlalpan Freeway and to avoid accidents (Figs. 16a and 16b). Erection equipment used for the biggest prctensioned elements consisted of one R2.5 ton (75 0 crane and another of 154 ion ( 40 ti capacity, for the Vhmieipio...

Precast Pretensioned Elements

To transport most of the pretensioned elements from the precast plants to the job site, a 50 ft (15 m) long trailer was employed. However. tor the longest elements, trucks with three axles each and a lowboy trailer with eiuht axles were used (Fig. 27). Transportation of most of the ire-Last concrete elements was carried out in one day, during the early morning hours, except for the largest central prctensioned elements for the main span (C-1) and support elements (S-1), which were hauled at...

Superstructure Components

As shown in Fig. 5, the longitudinal box girders of I hi. bridges arc made up of precast, pretensioned concrete support elements that bear on the columns and centra elements that bear on the support elements. These principal precast concrete elemenis arc described in this section, along with the transverse members, topping and connections. There are two types of stipporE elements. The S- elements are located over the two groups of columns nearest the center of the bridge where thev support the...

Aa Cross Section

Elevation, cross section and reinforcement details for the partially precast transverse beams. Note 1 ft 0.3048 m 1 in. 25.4 mm. Fig. 22. Plan, elevation, cross section and details of connection between support main beams and the central main beams. Note 1 ft 0.3048 m 1 in. 25.4 mm. Fig. 23 Each of the bridges has a cast-in-place concrete stairway, accessing the sidewalks that permit people to cross the Tlalpan Freeway. over the columns. This permitted the vertical steel in the column...

Jos Ma Riobo Martin

Riob o Consulting Engineers Mexico City. Mexico Twin precast, pretensioned concrete bridges were recently built over Tlalpan Freeway in one of Mexico City's most densely populated areas. Designed for a clear span of 170 ft 52 m) over a major freeway, they bring a new dimension to bridges for heavy traffic urban areas in seismic zones. Each of the twin bridges consists of three longitudinal girders with a total length of 1539 ft (469 m). Each girder comprises 13 pretensioned elements of hollow...

Precasting Operations

Precasting of the central and support pre ten si on ed elements was done in two different plants, IS.7 and .17.4 miles 30 and 60 km , respectively, from the job site. Support and central preten- Table 2. Construction schedule for the twin bridges. Foundation P retail concrete piles Pie-uit ciiiig, driving Excavation Footings Biickriii Transverse heams Earthwork Concrete loppin Asphalt i ' lt gt . Precast concrete structure Mold mantiiiiUtire Precast concrete elements Hauling, erection sioned...