Interim Calculation Rules for Building Construction
- Five codes were authorized, without precedence among them: the Canadian CNBC, ACI-318, the International Building Code, Eurocode 8 and CUBiC 1985. Any other code requires express MTPTC authorization. This replaced an open situation in which each foreign or Haitian practitioner used the code of their own country.
- The document is explicitly a stopgap and says when it dies: the requirements are interim and will be erased as soon as Haiti's own standards, then in preparation, appear. It completes the press note of 9 February 2010, issued a month after the earthquake, which had authorized four international codes for one year.
- The seismic hazard is quantified for the first time in a form engineers can apply. USGS derived Haiti-specific hazard maps using the same method as for the United States and Canada, giving peak ground acceleration at 2 percent probability of exceedance in 50 years, a 2,500-year return period, and Port-au-Prince stands at 68 percent of g. Spectral accelerations at 0.2 and 1.0 seconds are mapped nationally with enlargements for Port-au-Prince, Les Cayes and Cap-Haïtien.
- The reason the maps had to come from modelling rather than measurement is stated plainly: despite knowledge of Caribbean tectonics, few or no ground-motion and acceleration measurements had been taken at strategic locations during recent decades, so the design spectra engineers need did not exist.
- Wind is zoned into four bands with reference speeds of 100 mi/h (160 km/h) in Zone I rising to 130 mi/h (208 km/h) in Zone IV, taken as 3-second gusts at 10 metres in flat open terrain, and the document notes these are consistent with the values used for the Dominican Republic and Jamaica. Equivalent reference values are tabulated for each authorized code, so a designer using the British, Canadian, European or Caribbean code does not have to convert: ASCE 45 to 58 m/s, BS 6399-2 31 to 41 m/s, CNBC dynamic pressures 0.61 to 1.02 kPa, Eurocode 32 to 42 m/s, and CUBiC 0.68 to 1.15 kPa.
- Risk categories are set at four levels, low, normal, high and civil protection, with the highest reserved for facilities delivering essential services in a disaster: hospitals, telephone exchanges, power stations and distribution substations, transport control centres, water pumping, treatment and storage, critical national defence functions, fire, police and rescue stations, and radio and television stations.
- Live loads are minimum values adapted from tables 4.1.5.3 and 4.1.5.10 of the 2005 Canadian code, published in both SI and US units, with concentrated loads applied on a 75 cm square and the more critical of the uniform or concentrated case governing.
- One historical detail differs across the corpus and is worth noting rather than smoothing: this document says Port-au-Prince was destroyed by earthquakes in 1751 and 1771, while the Prepetit essay held here singles out 1751 and 1770. Both list 1770 and 1771 among years of shaking.
- The document also points to a companion product, the seismic macrozonation map of metropolitan Port-au-Prince, hosted at Purdue and at lnbtp.gouv.ht, which supplies the areas corresponding to soil categories B and C that the rules then use.
MTPTC's interim calculation rules for building design in Haiti, issued in 2011, which put the country's seismic hazard into design values an engineer can use. The hazard is expressed as peak ground acceleration as a percentage of gravity (g = 9.81 m/s²) with a 2 percent probability of exceedance in 50 years, a 2,500-year return period consistent with modern code practice, and the figure for Port-au-Prince is 68 percent of g.
The rules supply acceleration spectra for the 0.2 second and 1.0 second periods at that same exceedance probability, nationally and then region by region, with separate figures given for Port-au-Prince, Cap-Haïtien and Les Cayes, using USGS data. That regional disaggregation is what distinguishes a usable code from a national average: a building in the Cap does not face the capital's spectrum.
The document also sets occupancy and loading criteria alongside the hazard, including meeting places with at least 80 percent of the surface occupied and weight thresholds between 3,600 and 9,000 kg, so the design inputs cover use as well as ground motion. As interim rules they are the operative reference between the 2010 earthquake and a full national code, which is what makes their design values worth citing precisely.
How to cite
Ministry of Public Works, Transport and Communications (MTPTC), 2011, Interim Calculation Rules for Building Construction, https://www.mtptc.gouv.ht/media/upload/doc/publications/regles_de_calcul_interimaire.pdf