Structural Investigation Report

Transcription

1 Structural Investigation Report State University Hospital of Haiti and Two Ministry of Public Health Buildings Structural Investigation Ministry of Public Health Buildings Port-au-Prince, Haiti April 18, 2012 Miyamoto Project Number:

2 Contents Introduction... 1 Description of the Location... 1 Level of Strengthening... 2 Observations and Discussion... 2 MSPP 1: DOSS... 3 MSPP 2: DPEV/UCPNANUH... 7 Observations and Discussion of Non-Structural Aspects... 9 Conclusions Limitations... 10

3 Introduction This report is a supplement to University of Haiti Hospital Structural Investigation Report issued by Miyamoto International on March 30, This report may be read independently or as an addendum. Some of the information provided in the above mentioned report is repeated herein for clarity. See the Conclusion for our comments on how the buildings herein compare to those in the above mentioned report. On April 12, 2012, this office visited the subject site to visually assess the earthquake damage to multiple buildings, resulting from the subject M7.0 event on January 12, 2010, and its subsequent aftershocks. In addition, we observed and analyzed each of the subject buildings with regards to their potential structural vulnerabilities to future earthquakes. In this report, we present repair recommendations for the observed earthquake damages and potential strengthening strategies for the potential vulnerabilities for each building. We also discuss the level of recommended strengthening and what is considered standard for the lateral-load capacity of hospitals. Finally, we discuss some significant non-structural observations and vulnerabilities. Description of Location The site is located between Rue St-Honore, Rue Oswald Durand and Avenue Lamartiniere, Port-au- Prince, Haiti. The subject property consists of two (2) buildings, as shown in Figure 1. Buildings not included in the scope of this report are minor structures, outbuildings, shipping containers and other temporary structures. Figure 1 Overall Map Page 1

4 Level of Strengthening The buildings have a similar construction type that is common in Haiti: lightly reinforced non-ductile concrete columns, supporting lightly reinforced concrete beams with hollow concrete block (HCB) walls used as infill, and concrete slabs at the floors and roofs. It is our experience that buildings of this type of construction and vintage have little to no lateral load capacity. These buildings are very vulnerable to earthquake damage. Our recommendations focus on the structural rehabilitation of critical structural weaknesses that typically lead to failure and potentially collapse of these types of buildings during a seismic event. The final rehabilitation recommendations must meet the requirements of the current International Building Code (IBC) for Hospital Occupancy. As hospitals are critical post-disaster facilities, they are typically designed to a higher performance standard. It is also important to pay close attention to support and anchorage of non-structural equipment that must be operation after an earthquake. Our recommended strengthening schemes focus on practical and cost efficient rehabilitation. In some cases, we recommend adding structural elements, like exterior concrete shear walls, that may cover or conflict with some exiting architectural features, like window penetrations. Please note there are several rehabilitation options, like bucking-restrained braces, that can be designed to accommodate these architectural features. However, in many cases, rehabilitation schemes with these options are much more expensive to implement. Observations and Discussion Following are the earthquake damages that we observed during our site visit and investigations of the existing buildings, along with our recommended repairs for these damages. In addition, we analyzed the existing buildings for potential structural vulnerabilities and critical structural weaknesses, and present a seismic rehabilitation and strengthening scheme for each building. Page 2

5 MSPP 1: Direction d Organisation des Services de Santé (DOSS) Ministry of Public Health Buildings The building s description is as follows: 1. Located at the south-central area of the site (refer to Figure 1). 2. GPS coordinates: N , W Approximate 380 m 2 footprint. 4. Adjacent to the main gate. 5. Site is relatively flat. 6. One story (refer to Figure 2). 7. Construction is of standard local practice, which consists of cast-in-place (CIP) concrete, beams, columns, roof slab and hollow concrete block (HCB) & rubble infill walls. Figure 2 DOSS Page 3

6 Damage We observed the following structural damage due to the subject event: 1. Minor cracking of concrete beams: We recommend repairing with epoxy injection. 2. Minor cracking of HCB infill walls (refer to Figure 3 and 4): We recommend repairing with epoxy and grout injection. Vulnerabilities We observed the following potential structural vulnerabilities (refer to Figure 6): 1. Lateral load resisting system (refer to Error! Reference source not found.5): There are no structural elements intentionally designed to resisting earthquake loads. We recommend providing reinforced concrete shear walls designed for earthquake loads and tying them together with collector elements. Figure 3 Minor cracking of HCB infill walls Figure 4 Minor cracking of HCB infill walls Figure 5 Lateral load resisting system Page 4

7 Figure 6 Rehabilitation scheme Page 5

8 MSPP 2: Vaccination/Nutrition (DPEV/UCPHAHUH) The building s description is as follows: 1. Located at the north-east area of the site (refer to Figure 1). 2. GPS coordinates: N , W Approximate 1200 m 2 footprint. 4. Adjacent to the roadway. 5. Site slightly slopes up from the west. 6. Two story structure (refer to Figure 7). 7. Construction is of standard local practice, which consists of cast-in-place (CIP) concrete, beams, columns, roof slab and hollow concrete block (HCB) infill walls. Figure 7 DPEV/UCPNANUH Portions of the first floor earthquake damage are repaired and covered by new paint by the time of our visit. Page 6

9 Damages We observed the following structural damage due to the subject event: 1. Collapsed parapet (refer to Figure 8): We recommend repairing with reinforced masonry and bracing with steel angles to the roof. 2. Minor cracking of concrete columns: We recommend repairing with epoxy injection. 3. Minor cracking of concrete beams (refer to Figure 9): We recommend repairing with epoxy injection. 4. Minor cracking of infill walls (refer to Figure 10): We recommend repairing with epoxy and grout injection. Vulnerabilities We observed the following potential structural vulnerabilities (refer to Figure 11): 1. Lateral load resisting system: There are no structural elements intentionally designed to resisting earthquake loads. We recommend providing reinforced concrete shear walls designed for earthquake loads. 2. Re-entrant corner in roof diaphragm: This configuration tends to result in high force concentration and can crack & separate during a seismic event. We recommend providing continuous ties or collector struts at each re-entrant corner. 3. Interior low height walls: These walls are unrestrained at the top and tend to topple during a seismic event. We recommend bracing the top of the walls with steel angles or light gage metal framed kicker braces. Figure 8 Collapsed parapet Figure 9 Minor cracking of concrete beams Figure 10 Minor cracking of infill walls Page 7

10 Figure 11 Rehabilitation scheme Page 8

11 Observations and Discussion of Non-Structural Aspects In the course of our investigation, we observed conditions that may also affect the function of the facility and the performance during an earthquake and operation after an earthquake. Although the following items are not structural, we believe that these points should be addressed: 1. Exposed reinforcing (refer to Figure 12): This condition poses a potential source corrosion and water ingress. In addition, the exposed column reinforcing poses a safety hazard for persons who may access the roof. We recommend the reinforcing be cut back at the roof and proper concrete cover be provided. 2. Makeshift electrical services (refer to Figure 13): As structural engineers, we cannot comment on how well the current electrical services conform to safety standards, but we recommend the electrical services be reviewed by a professional electrical engineer. Figure 12 Exposed reinforcing 3. Unrestrained roof-top appendages (refer to Figure 14): We observed parapets, water tanks, generators, HVAC units, ducts and antennas on the existing roofs. These appendages have the potential to displace and dislodge, becoming a safety hazard during a seismic event. We recommend these appendages be securely anchored. Figure 13 Makeshift electrical services Figure 14 Unrestrained parapet Page 9

12 Conclusions Of the two buildings, the most significantly damaged we observed during our site investigation occurs at MSPP 2: DPEV/UCPNANUH. It is the more vulnerable, too. Considering all buildings reviewed in this report and the University of Haiti Hospital Structural Investigation Report, the MSPP buildings are not the most significantly damaged or vulnerable. The nature of our report is from a structural engineering perspective, but we presented several nonstructural aspects that we consider to be a priority to public health and safety. We understand the funding constrictions that might be in place and hope that there is priority giving to these nonstructural aspects as well. Limitations This report is based on a visual survey of the subject buildings in order to obtain an overview of existing conditions. Our observations are limited to what was visually accessible during the time of our visit. Furthermore, as the facility was in operation during the time of our visit, we did not move equipment or other objects that might obscure our observation, nor did we remove any finish material to confirm elements of the structural systems. Geotechnical aspects are beyond the scope of this report. This report does not express or imply any warranty of the existing structures and was developed based solely on visual observations made during a site visit of the existing property. Our services are provided at a level consistent with the standard care of engineers in the practice of structural and earthquake engineering. Very truly yours, Miyamoto International, Inc. Joel-Alexander Hampson, MASc, PEng, LEED AP Associate Bob Glasgow, M.S., S.E. Principal H. Kit Miyamoto, Ph.D., S.E. President & CEO Page 10