Degenkolb Reconnaissance Team in Haiti – Day 7
Blog Day 7: Saturday March 27th
Downtown Port au Prince
We decided to start our Saturday morning at the market – the Iron Market or Marche de Fer, a light steel frame building from 1889 that was originally intended for the Cairo train station but instead was brought to Port au Prince. The building is set among a lively retail section (although it appears sellers outnumber buyers by a wide margin) along the streets in the middle of downtown Port au Prince where the majority of buildings are collapsed, and virtually all show indications of the earthquake. The “building” has no walls and used to house an open air market under its roof. We learned that at some point in time a concrete mezzanine level was added in the central portion of the market. That mezzanine level was built on a weak concrete frame that failed in the earthquake and sheared the column base connections of the Iron Market centerpiece as it collapsed. This highlights the detrimental effect of the poorly designed concrete mezzanine adjacent to the well-performing steel frame. The remainder of the steel frame is in salvageable condition, although significantly corroded in some areas. The central portion of the market is already being rebuilt with a high priority as a symbol of the reconstruction effort downtown.
The central portion of the Iron Market is tilted after the heavy mezzanine sheared the cast iron columns from their base. (above)
Mike, Henry, Mark, and our driver/interpreter/security guard Francois viewing the partially collapsed Marche de Fer. Stepping through rubble of concrete and block has taken a toll on my boots, which have held up just long enough thanks to the duct tape – don’t leave home without it. (above)
We walked through the market politely declining to buy any goods from street vendors, and stopped at a brightly painted mint green pharmacy building. This modern looking 3-story building in the middle of the heavily damaged zone appeared to not have a scratch on it. In talking with the store manager while walking through the building, we learned that the building was designed around 12 years ago by a local Haitian engineer, a relative. The same engineer performed the post-earthquake assessment within two days and finding almost no damage, the owner re-opened the pharmacy back to business. The concrete frame with unreinforced block wall infill was a familiar structural system, but the apparent quality of the materials, the size of the columns and beams, and amount of wall provided far exceeded the typical building here. But this building demonstrated that this type of construction common in Port au Prince can perform very well.
Navigating our way through downtown Port au Prince among building damage and heavy vehicle traffic. (above)
The brightly colored Pharmacy (again with the coincidence of the bright paint?) performed very well in the earthquake with almost no damage and was open for business within days. The building was surrounded by collapsed structures in one of the most heavily damaged areas of Port au prince. The street vendors supplement the Pharmacy. (above)
As we made our way out of the densely packed streets of downtown, we reached a building that can potentially serve as a valuable data point for concrete frame with block infill. Revisiting the Hotel Nova Scotia, we can see that the infill partition walls range from heavily damaged and collapsed at the bottom, moderately damaged and partially collapsed near mid-height, and undamaged and completely intact at the top of the building. The underlying reinforced concrete frame appears reasonably well detailed, although flexible. With a little more study we will try to estimate the limit of where the infill walls worked for this particular building, to help establish a guideline for the amount of infill wall that is needed for this type of construction in Haiti.
The Hotel Nova Scotia in downtown is a key example of a building that suffered damage but could potentially be repaired rather than demolished. Note the reduction in damage up the height of the building. The apparent shear failures in the columns at the second floor are actually part of the masonry exterior cladding, the vertical load carrying system is essentially undamaged. (above)
Petionville
In the afternoon we drove up the hill to Petionville, a middle class suburb of Port au Prince which suffered far less damage. Entering this area, it becomes immediately clear the difference in living conditions between ‘down the hill’ and ‘up the hill’.
Click here for the New York Times article for more.
Or the slideshow with audio
Our first stop in Petionville was the Caribbean Supermarket, a collapsed building that was formerly the largest supermarket in Haiti. In this area, there was very little damage, yet this relatively modern building collapsed, evidently from very little wall along the front open façade. Even the adjacent building, the epitome of a soft story concrete frame, with infill wall everywhere but the ground floor, showed almost no damage.
The largest supermarket in Haiti catastrophically collapsed in the upper levels with large window openings and little solid wall. (above)
The building adjacent to the market, a soft story if there ever was one, survived with almost no damage to the concrete frame. (above)
A large quarry providing aggregate and sand to Port au Prince was just up the road from Petionville in La Boule, so we decided to visit. Through various discussions, we learned that the government has temporarily closed down operations at this quarry, mainly because of the often blamed white sand aggregate. With the backdrop of the impossibly high steep cuts out of the mountains, Mark decided to perform some informal “drop tests” on some local concrete block samples. We should have negotiated the purchase price first, as we definitely paid too much for the block (and did not get a receipt, sorry Maureen!). Worse, we did not conclusively prove or discredit our theory about the white sand block. Some of the blocks did not break when dropping them from 4 feet, some broke into 2 or 3 pieces, and a few shattered like glass; the poorest blocks could even be broken by hand (maybe not by everyone, but at least by Mark and I…). Investigating the broken pieces of block, it may be that the amount of cement is perhaps more critical than the presence of the white sand. Despite not inconclusive results on the white sand or cement, these block tests indicate the great variability in the material quality throughout the region.
A large aggregate and sand quarry supplying Port au Prince was shut down by the government after the earthquake. (above)
Another building that stood out in Petionville was the Hexagone building, a tall structure that appeared more modern. The damage pattern seen from the outside of this building is what we would expect of a building in the United States after a large earthquake – distributed shear cracking in wall piers and some spandrel beams, but preservation of the overall gravity system. There was clearly a low level of ground motion in this area since no other nearby buildings suffered damage. For the building of this size, the concrete frame with block infill was an adequate solution perhaps for Life Safety, but will require repair under even this moderate-to-low level of ground shaking.
Hexagone Building in Petionville with shear cracking at infill block wall piers throughout the building. This represents how we think buildings in the US would perform in a large earthquake, yet judging by the nearby damage, the shaking here was relatively low. (above)
On our drive back down the hill from Petionville, we observed steep hillsides covered with houses. There were sections where the houses had been heavily damaged from the earthquake. Fortunately, we did not see any evidence of landslides in this area. A landslide on one of these steep slopes would take out all the houses along the entire slope resulting in terrible loss of life. We suspect that the shaking was less in this area compared to other areas and if so, this may be why a landslide did not occur in this area. It would be interesting to hear the thoughts from a geotechnical engineer familiar with the soil of the area regarding this topic. It seems likely that there is a landslide risk as landslides occurred in several locations throughout the region, including farther west along the same line of hills. As the population increases and additional housing is built on these hillsides, it appears that the risk of major loss of life from a landslide could increase as well.
