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Bridge Diaphragm

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The main function of diaphragms is to provide a stiffening effect to deck slab in case bridge webs are not situated directly on top of bearings. Therefore, diaphragms may not be necessary in case bridge bearings are placed directly under the webs because loads in bridge decks can be directly transferred to the bearings.On the other hand, diaphragms also help to improve the load-sharing characteristics of bridges. Diaphragms also contribute to the provision of torsional restraint to the bridge deck. Diaphragm will be used also to resist stresses that occurs during the post-tensioning process. Post-tensioning hardware are casted inside the diaphragm.

Types of diaphragm:

  • Diaphragm at the span end: this type of diaphragms will be located between two bridge spans or at the bridge abutments. Expansion joints will be used to connect bridge spans. This expansion joint will be installed on the diaphragm, as shown in detail A in figure no:2.
Figure 2



In the figure, no 3we can see diaphragm located above the abutment — the expansion joint placed between the diaphragm and the backwall. Backwall cast with the abutment. Approach slab connected to back wall. Approach slab provided to ensure smooth driving, and it is a transition zone between embankment and bridge.
Figure 3

The figure no 4 showing the reinforcement for abutment diaphragm

Figure 4


  • Intermediate diaphragm: this diaphragm located above the pier column for continuous spans. This type of diaphragm will not receive expansion joint, and it will transfer the loads from the spans from both sides. 
Figure 5








Diaphragm reinforcement sample
Figure 6


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Mohammad
My name is Mohammad Hamdan, and I am a Civil/bridge Engineer with extensive professional background and experience in the field of construction. I have 10+ years of experience in the construction field. During my professional career, my emphasis has been placed on structural projects, mainly bridges, infrastructure and roads. Reading and practicing the design of structures is my passion.i was lucky to be a part of a big team that executed major highway interchanges. I believe in spreading the knowledge, thus, i compose these courses to share my experience and knowledge. My course focuses on the practical side of construction field. On other word, i am sharing some of what new engineers need to know about construction field. Beside working on construction field, i love writing some articles on my website ( curious civil engineer) Moreover, i wrote some engineering papers, you can check them  by searching my name on Google (Mohammad mamon Hamdan)