pnu’s apm unsymmetrical beams | minimizing distortion 7 Closet box section type guideways were chosen for the entire (75 % straight 25 % curved) alignment requiring a precast concrete technique of construction. For the straight sections, the box girder was executed using unsymmetrical precast pre-tensioned C-beams assembled together using stitching concrete. At transfer, the unsymmetrical precast pre-tensioned beam was studied to avoid distortion that could characteristically occur with unsymmetrical beams. The cast-in-situ R.C. deck slab was then constructed using precast slabs resting on the formed box girder section. No formworks were needed for the whole bridge box section construction because of the efficiency gained from the use of precast beams and slabs. For the curved APM parts, a precast post-tensioned segmental construction was considered. 8 This article summarizes the findings of a technical paper accepted by the International fib Symposium and presented by Dr. Essam Ayoub in Prague 2011. The authors present the efficiency obtained using precast construction technique for the PNU elevated APM guideway. The paper also discusses the pretensioned strands arrangement for unsymmetrical precast C beams (straight parts) to minimize distortion occurring at transfer due to the unsymmetrical characteristics of the precast beams. Guideway straight parts precast C-beams The straight parts of the APM’s guideway were constructed using doubly unsymmetrical precast pretensioned C-beams with several span lengths adopted. These include 22-27, 30 and 36 m simple spans each with two precast C-beams assembled to form the final box girder section of the APM guideway. The sequence of construction resulted in the most efficient box girder section construction with a 45 MPa concrete grade. For the 36-m span straight bridge 75 strands, five are located at beam top and adopted for each of the two precast unsymmetrical pre-tensioned beam. The pre-tensioned strand has an ultimate strength of 1770 MPa and an area of 150 mm2. Ten strands are de-bonded for a distance of 8.9 m from support and 34 strands are de-bonded for a distance of 3.4 m from support. Because of the appropriate selection of transverse eccentricities of the pre-tensioned strands the distortion of the beam is barely noticeable. 6,8 Constructed 34.8 m unsymmetrical precast C-beam lateral and top views 7 Double precast unsymmetrical C-beams assembly 9 C-beam and precast slab close up 10 Precast slabs installation used as scaffolding for the cast in place top slab 11 Box Bridge Girder resting on piers 9 10 11 5