Post-tension design review

A post-tensioned slab design is usually produced quickly, often by the PT specialist contractor, and often under programme pressure. A review by an engineer who designs PT slabs every week finds the issues that matter, while the drawings can still be changed at little cost. Iron Axis reviews the calculations, the analysis model and the drawings together, so that what is checked is what will be built.

Review items

• Design basis: code and edition, loading, finishes, fire rating, exposure, concrete grade, transfer strength and the PT system data used for friction and anchorage losses.
• Analysis model: support conditions, column and wall stiffness, design strips, load balancing ratio and the treatment of restraint from cores and walls.
• Serviceability: stresses at transfer and in service, long-term deflection with creep and shrinkage, and crack control where the slab is not fully compressed.
• Strength: flexure, one-way shear and punching shear at every column, including edge and corner columns and columns next to openings.
• Detailing: tendon profiles and cover, anchorage zones and bursting steel, minimum bonded reinforcement, pour strips and construction joints.
• Drawings: consistency between calculations, tendon layouts, profiles and stressing schedules.

Each finding is classed by severity so the team knows what must change before approval and what is a recommendation. Comments are written so the designer can close them, not just as a list of doubts.

Typical users are structural consultants of record checking a contractor PT design, main contractors who want comfort before the pour, and developers who want a second opinion on a slab that looks too thick, too thin or too heavily reinforced. If the review shows room to save material, the next step is usually PT design optimisation.

Reviews are carried out against ACI 318-19 and the PTI recommendations, or the code named for the project, such as SBC 304 in Saudi Arabia or QCS in Qatar. Please send the calculation report, the analysis model if available, and the full drawing set. Partial sets can be reviewed, but the report will state what could not be checked.

Turnaround depends on the size of the set; the scope and timeline are agreed before work starts, so there are no surprises. Questions raised during the review are sent as they come up, so the design team can start answering early instead of waiting for one long report at the end.

Every emirate, and some master developers and free zones, has its own authority with its own way of receiving structural and post-tension submissions. The engineering principles do not change, but the code edition, the format of the calculation report, the drawing requirements and how comments are raised do. Our engineers have worked with these requirements over 15+ years in the UAE and the wider GCC, so a PT design or review from Iron Axis is prepared to the criteria of the authority that will check it.

At kick-off we confirm which authority has jurisdiction over the plot, the governing code and edition, and the consultant's specification. The calculation report, tendon drawings and comment responses are then prepared in the format that authority expects. Submissions themselves are made through the consultant of record.