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Improving the seismic capabilities of the schools in Joyabaj, Guatemala / Alison Bernero.

by Bernero, Alison

Earthquake resistant design

Buildings -- Earthquake effects -- Guatemala

Reinforced concrete construction

96 leaves : ill. ; 29 cm.

Thesis advisor: Dr. Douglas Stahl

Committee members: Dr. John Zachar, Dr. Carol Diggelman

Introduction -- The current typical school design -- Materials research -- Seismic analysis of the current school -- Proposed changes to the typical school design -- Conclusion -- References -- Bibliography -- Appendix A: Research trip details -- B: Connection accessories data -- C: Typical school drawings with EWB-Chicago modifications.

Most of the villages in the region of Joyabaj, Guatemala lack the funds and governmental support necessary to construct schools. NGOs have stepped in to build schools per a standard, but minimally engineered design. Construction is led by local masons and the building methods are traditional to the region. Earthquakes continue to be common in the area, and the seismic capabilities of these schools are a concern. The Joyabaj school structure is a textbook example of confined masonry construction. Masonry panels are framed by reinforced concrete confining members. In May of 2009, the author travelled to Joyabaj region to gather samples of the material used in typical school construction and to observe typical school construction methods.

Flexural reinforcement available in Joyabaj was subject to tensile tests. The rebar used by MSOE-EWB possessed strengths similar to those of Grade 60 bars in the United States and can be classified as Grade 60 rebar. The bars in Joyabaj, however, were too weak to receive the same classification. They fall into the Grade 40 classification.

Aggregate samples were subject to sieve analyses in-country and brought back to the U.S. for further visual inspection by a qualified Geotechnical Engineer. Fine aggregate samples were taken from distributor Que Maya and local construction sites. The Que Maya sand proved to be of significantly higher quality than the sand typically used by the masons, which was filled with strength-compromising mica. Coarse aggregate was taken from distributors Que Maya and Joyabaj Quarry. The coarse aggregate from Que Maya had several advantages over the Joyabaj Quarry aggregate used by EWB-MSOE and was overall more suitable for concrete.

Mortar and concrete samples were made using Guatemalan-produced Cemento Progreso. Compression tests were performed on three batches of mortar cubes containing different combinations of Guatemalan and U.S. sand and cement. Results suggested that both the sand and the cement used in Joyabaj are of a lower quality than what is typical in the U.S. However, the mortar made with Guatemalan Cement, althougher weaker than U.S. mortar, still exceeded strength expectations. The sample which included Guatemalan sand was less than half the required strength. It was concluded that with the proper mix ratios and aggregate of a decent quality, Cemento Progreso can provide adequate mortar strength. The concrete, mixed using the "Volcano Method" by Joyabaj masons possessed a w:c ratio of approximately 0.57. The 70-day compressive strength of the concrete was found to be 825 psi. Further testing of this mix is recommended using ASTM C1019, The Standard Test Method for Sampling and Testing Grout.

This paper proposed three options to achieve seismic capability. The first option, to achieve roof diaphragm action was found to be impossible due to connection strengths. The second option was to replace the steel roof with CIP concrete. This was found to be unaffordable. The final option, to improve the integrity of the non-diaphragm roof as-is was found to be possible assuming proper welding techniques and a long enough bearing length of the rafter and beam assemblies.

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