Photo: Daniel Chavez
Imagine coming to work one day to find that the building codes, material references, product guides, and other resources vital to your work as a structural engineer are no longer applicable. Imagine that whatever scant resources are available are incomplete and likely also written in a language in which you are not yet fluent. There is no department of buildings as you know it, nor third-party inspection agencies, nor legal requirements for inspection, and the construction workers you encounter often lack formal training.
In this reality, material quality certification is not enforced and your project is not just design and construction administration of one building, but rather providing shelter for thousands of families and students who have been displaced by a massive earthquake, tsunami, or typhoon, in diverse and often remote locations.
These are just a few of the challenges and prospects encountered by engineers undertaking to provide technical assistance for reconstruction of essential building stock and sustainable permanent change to construction practices in the wake of crises in developing countries. This article provides a look at experiences of several engineers working with a non-profit (Build Change) in locations around the world and the challenges faced during each phase of the process, from design through construction.
Most frequently in the aftermath of natural disasters such as earthquakes and hurricanes, the same inadequate building types responsible for deaths of poor and middle income persons in developing countries have been rebuilt in the same way, setting the table for further economic distress and unnecessary loss of life in a future event. The houses and schools serving these vulnerable populations typically are conceived and built in what is known in the development world as the “informal sector.” Without a change to these informal sector construction practices, the cycles of life and investment loss will continue to affect those who can least afford it.
Without assistance to gain autonomous knowledge and skill, the people affected most by natural disasters are insufficiently equipped to help themselves. However, valuable precedent has shown that with training in disaster-resilient, technologically and culturally appropriate construction techniques, such scenarios are not inevitable.
Photo: Lola Gomez
Design standards: Nepal
An experienced engineer may need to flip through material design guides only sparingly as the rules of thumb for minimum thicknesses, reinforcement ratios, and the various equations for allowable strengths have become ingrained. A challenge arises when the requirements of these guidelines are not applicable, for instance, because the construction typology, in the case of confined masonry with brick or stone, is not common in the developed world, or because the reality of limited construction technologies physically impedes direct application of the full standard.
In Nepal, magnitude 7.8 and 7.3 earthquakes hit in succession in the spring of 2015, annihilating half a million homes and leaving another half as many damaged. Several thousand school buildings were also destroyed. Although Nepal has developed a Nepal National Building Code largely based on the Indian Standards, its implementation has yet to be required in rural areas and it is relatively prescriptive in nature, with mandatory provisions for building construction, rules of thumb for particular construction types, and general guidelines for construction types encountered in remote rural areas.
Whereas Nepal has variable topography, the guidelines do not consider site-specific geotechnical issues that contribute to the amplification of ground accelerations and velocities or employ a risk-targeted approach to earthquake-resistant design. The code does not provide technical literature on repair and retrofit of existing structures nor mandate retrofitting for existing buildings.
In rural areas, where 92 percent of houses are owner-built (see Note 1, page 18), engineered building materials and construction typologies are often unavailable or unachievable due to a combination of inaccessibility and prohibitive expense. According to an engineer working in Nepal, “One of the biggest technical challenges in the rural areas of Nepal is developing and justifying a structural evaluation and retrofit design methodology that provides a life safety performance level using random stone masonry with mud mortar as the primary lateral force-resisting system.”
This is needed because this is the most common existing building type in rural Nepal, and houses that suffered damage but were not destroyed will likely not receive any aid for reconstruction. Yet, many homeowners acknowledge a need not only to repair, but to strengthen these homes.
Build Change’s Nepal team is currently developing strengthening techniques for random stone masonry and mud mortar construction that, in the words of an engineer in Nepal “is sensitive to social, cultural, psychological, financial, and political issues in order to provide a long-term structural solution.”
This will include looking to research from around the world, laboratory testing to establish default strengths, field testing for constructability, and validation by the government’s technical authority for reconstruction. The overall aim is keeping it simple enough to be adopted widely and robust enough to significantly improve performance.
Photo: Lizzie Blaisdell
In modern structural engineering practice, material specifications are standardized and reliable input values receive little more than passing thought. In many areas of developing countries, lack of access to quality building materials is a major concern. Although a rare typology in most developed countries, confined masonry — where walls of masonry (brick or block) are surrounded in-plane by reinforced concrete confining elements — is the predominant construction type in many developing locations and can be earthquake-safe when constructed properly and with good materials.
Throughout Indonesia, the quality of clay brick used for masonry construction is so low that in some cases bricks can be broken in half by hand, may erode substantially within a year where exposed to weather, and are so irregularly shaped they hamper construction of a plumb wall. The Indonesian Building Standard sets minimum strengths for three classifications of brick, but there is not an agency in place to monitor material quality or distribute certifications.
Since the 2004 magnitude 9.1 Indian Ocean earthquake and tsunami, which resulted in 225,000 casualties in Northern Sumatra alone, Indonesia has regularly experienced fatal earthquakes in excess of magnitude 6 (see Note 2, page 18) due to the proximity of a plate boundary and a major fault line that straddle the western boundary of the island nation. In West Sumatra, a magnitude 8.8 earthquake is predicted to bring with it a tsunami within the next few decades (see Note 3, page 18).
Recognizing the high level of risk in Indonesia, and that improving production standards would be vital to increase brick strength, regularity, and durability, a team in Sumatra is working with brick producers at their rural production kilns. Simple field tests have been developed to help producers choose better raw materials, estimate proper firing temperatures, and test brick strength for quality control. Local universities are working with the team to provide rounds of compressive testing to measure progress, and an affordable Three-Point Test machine design was given to community leaders to allow for self-monitoring in the absence of government oversight.
According to an engineer in Indonesia, “The Indonesian Building Standard requires a 5-MPa (725-psi) (see Note 4, page 18) minimum compressive strength for bricks in all construction projects. This is not enforced and typical production standards were averaging 2 to 3MPa. We’ve been able to double or triple the highest values in some cases and are working to set up standards to ensure sustainability of higher strengths. The reality is that there is imminent need for new schools and homes, and to retrofit damaged or poorly constructed homes and schools for impending disasters. … Although the brick strengths achievable in these rural kilns are low by U.S. standards, it is simply not feasible to replace an entire vernacular construction method or to ship in alternative materials.
“With increased strengths we’re seeing in the brick program, a properly constructed confined masonry building will be more resilient. We are working with the local disaster preparedness board and the public works administration as well as several universities to educate them about the importance of materials strengths and the need for quality control measures.”
Plan review/permitting: Haiti and China
In informal neighborhoods, construction of private homes is often unregulated; neither the technical nor architectural aspects of a design receive review from public or private qualified technical persons. This lack of technical input and review can lead to substantial damages and loses. For example, in Haiti, the magnitude 7.3 earthquake that struck in January 2010 caused an estimated $2.3 billion in damages to private housing and displaced an estimated 1.8 million people from their homes (see Note 5, page 18).
Efforts to work with the relevant government agencies so that designs and design guidelines for projects are developed and reviewed by qualified individuals are being made. One engineer who worked in Haiti for several years reported, “We worked with the Ministry to incorporate the seismic evaluation and retrofit procedures for Haitian housing we had developed with the support of a private U.S. engineering firm into the Ministry’s Guidelines for Seismic and Hurricane Retrofit of Buildings. Then we worked to train the Ministry’s staff in using and applying the procedures. In one of our recent retrofit projects, a trained engineer from the government was allocated to work with us and review and approve each of the more than 180 house retrofit designs our engineers produced. It seems that more and more, the Ministry or municipalities are participating in the technical design review process for housing reconstruction projects.”
Also, for reconstruction projects, issues of land tenancy and ownership can be a considerable complication for permitting. An engineer in Haiti attests that, in practice, “there is no legal process of construction used in housing in Haiti. In practice, an informal owner buys material and pays a boss (builder) for the construction without making a permit, or plans, [or] even a land title. There is distinction of the land tenancy and the building tenancy, so you can own a house without owning the land.”
In Haiti, retrofitting and repairing existing homes has proven a simpler way to deal with the land tenancy issues and still increase the stock of safe housing because the owner and house remain, so validation of ownership and tenancy is not as difficult.
Knowing that construction is likely to continue unregulated, and that homeowners in the informal sector of these emerging countries tend to incrementally expand their homes as resources become available, one strategy is to include an allowance in the engineering design now for safe future modification and adaptation of the structure.
“Design a house to include future expansions within a set of predetermined parameters — [such as] a concrete roof so that a second story, with a light-framed timber roof, can be added at a later date,” one engineer recommended. “Or provide for a horizontal addition in one particular direction by extending reinforcing for future lap splicing, with an appropriate cover material to prevent corrosion prior to that time.”
In locations where a formal review process does exist, there can be other challenges to working with long-established agencies and practices. “In China, the biggest technical challenge was…we had a very difficult time convincing the government officials to put columns at the ends of the shear walls. They were convinced that it was unnecessary,” recalled an engineer who has worked in several locations. “We ran into resistance from government officials who were convinced that the Sichuan earthquake was a once-in-a-lifetime experience that will never happen again, so there was no need to design buildings to resist earthquakes of that magnitude.”
Photo: Karin Kuffel
Construction supervision: Philippines
In the absence of inspection agencies or building department oversight, rural construction projects require the engineer and technical team to provide close supervision in the field to ensure that details are properly executed and quality materials are used.
An engineer in the Philippines said, “We definitely see improved construction practices when we have supervising engineers and builder trainers constantly on site. …The hope is that…the contractors and builders will see that they have built a better and more resilient house or school, it was not that hard to alter the usual construction practices, and they will continue to use the new methods on future work where we are not involved because they are now ‘better builders.’”
Build Change teams in all locations have developed training sessions for local builders who may have years of experience but may not have been trained for disaster-resistant detailing such as decreased spacing of stirrups at beam-column connections, or in material quality control such as onsite slump tests. Training is bolstered by construction quality checklists, a tool that can be used by engineers, or simplified and used by homeowners and school communities in the absence of an engineer or trained inspector to identify “red flags” in the construction process.
Supervision of multiple project sites concurrently needs to be simplified and systematized in order to ensure that each phase of construction advances only when disaster-resistant construction requirements have been fulfilled in the prior phase and that the end product meets the life-safety standard of the design.
For engineers working in the Philippines, where in fall 2014 a magnitude 7.1 earthquake followed by a Category 5 typhoon left 14,500 houses destroyed, more than 1.1 million damaged, and 3.62 million people displaced, construction supervision and quality control have their own unique challenges.
An engineer described site-visit logistics in this country of 7,107 islands: “We have engineers and builder trainers commuting daily by a medium-sized panga (single-hulled boat with bamboo pontoons) to and from a housing project on a small island. … In the past week, we had to skip two days of construction supervision due to a passing small typhoon followed by a tropical storm.”
In addition to staff transportation, getting quality materials to a remote island site is very challenging in the Philippines. “Materials are purchased in the closest major town, then delivered to…a beach area in a nearby village. From there, the island homeowners have to pick up the materials and transport them to the island in their small fishing boats…all while keeping cement bags dry and intact, and concrete blocks in one piece!”
There is consensus among the engineers that in the end the realization of disaster-resistant homes and schools outweighs what can sometimes be frustrating and seemingly insurmountable challenges. An engineer recalled, “Seeing a house built and a family moving in is a measurable success. It’s not one building for a faceless entity, it’s 50 houses for 50 different families whose homeowners you have seen on a nearly daily basis during construction. …[It was] most gratifying to hear that a homeowner of a new house provided safe shelter for 53 people — family, friends, and neighbors — 17 families in all, in a 4-meter by 7-meter house during a recent typhoon — one pregnant woman included. Hard to believe they fit that many people in one house, but rewarding to know that the people felt safe enough to do that and were safe.”
Another engineer said, “In Nepal I was deeply moved by what I saw in Ramche. All but one house in the village had collapsed in the earthquake. The village was completely devastated, yet the people in Ramche were not mad, depressed, or bemoaning their fate but instead were ready to rebuild and eager to learn how to build back better. They inspire me to want to help them even more than I felt before I went there.”
Jennifer Anna Pazdon, P.E., has 10 years of experience in structural engineering consulting based in New York City and abroad. After nearly a year with Build Change in Indonesia and Nepal, she will step into the role of lead structural engineer for the Philippines this spring. She received her MSE from Princeton University in 2009.
Contributing authors are Lizzie Blaisdell, S.E.; Daniel Chavez, P.E.; Clement Davy; Tim Hart, P.E., S.E.; Karin Kuffel, S.E.; and Pierre Paya.
Build Change designs disaster-resistant houses and schools in emerging nations and trains builders, homeowners, engineers, and government officials to build them. To learn more about how to help reduce deaths, injuries, and economic losses through disaster-resistant, culturally appropriate, sustainable construction, visit buildchange.org.