Investigation of March 15, 2018 Pedestrian Bridge Collapse ...

1 Investigation of March 15, 2018 Pedestrian Bridge Collapse at Florida International University, Miami, FL Department of Labor Occupational Safety and Health Administration Directorate of Construction July 2019 Investigation of March 15, 2018 Pedestrian Bridge Collapse at Florida International University, Miami, FL 2 REPORT Investigation of March 15, 2018 Pedestrian Bridge Collapse at Florida International University, Miami, FL July 2019 Report prepared by Mohammad Ayub, PE, SE Director, Office of Engineering Services Directorate of Construction OSHA National Office Washington, Investigation of March 15, 2018 Pedestrian Bridge Collapse at Florida International University, Miami, FL 3 TABLE OF CONTENTS PAGE NO. 1. Executive Summary:*.. 9 2. Introduction: .. 13 3. Key Participants:.. 16 4. Description of Construction: .. 18 5. Peer review:** .. 36 6. The cracks.

2 39 7. The Collapse .. 83 8. Structural analysis: .. 103 9. Structural design deficiencies: .. 106 10. Conclusions* .. 113 * The executive summary and conclusions of the June 2019 Report has been amended see pages 12 & 114. ** The Peer review section of the June 2019 Report has been amended see page 37. Investigation of March 15, 2018 Pedestrian Bridge Collapse at Florida International University, Miami, FL 4 LIST OF FIGURES Figure 1 Location of the Bridge .. 13 Figure 2 Flow chart of the organization .. 17 Figure 3 Bridge as designed .. 18 Figure 4 Construction sequence .. 19 Figure 5 Main span truss PT bar details .. 20 Figure 6 Construction of the main span .. 21 Figure 7 Transportation of the main span .. 22 Figure 8 Bracing plan of the north end of the main span .. 25 Figure 9 Bracing of the north end of the main span .. 26 Figure 10 Cross section of the Bridge main span deck.

3 29 Figure 11 Main span deck end diaphragm and the post-tensioning tendons .. 30 Figure 12 Main span deck longitudinal tendon ducts .. 31 Figure 13 Diaphragm II reinforcement .. 33 Figure 14 Concrete testing report .. 35 Figure 15 Photo #1 in 2/28/2018 E-mail from MCM to 40 Figure 16 Photo #2 in 2/28/2018 E-mail from MCM to 41 Figure 17 Photo #3 in 2/28/2018 E-mail from MCM to 42 Figure 18 Photo #4 in 2/28/2018 E-mail from MCM to 43 Figure 19 Photo #5 in 2/28/2018 E-mail from MCM to 44 Figure 20 Photo #6 in 2/28/2018 E-mail from MCM to 45 Figure 21 Location of cracks in 2/28/2018 E-mail from MCM to FIGG as per BPA .. 46 Figure 22 North end of the main span truss during transportation, generally free of 47 Figure 23 Screenshot of Kevin Hanson s message to Sam Nunez on March 10, 2018 .. 49 Figure 24 Cracks at the west side diaphragm II MCM email of 3/12/2018 top face, by BPA.. 51 Figure 25 Cracks at the west side diaphragm II MCM email of 3/12/2018, by BPA side face.

4 52 Figure 26 Cracks at the east side diaphragm II MCM email of 3/12/2018, by BPA top face .. 53 Figure 27 Cracks on the east side diaphragm II MCM email of 3/12/2018, by BPA side face. 54 Figure 28 Diagonal cracks on the west side of diaphragm II on 3/13/2018, by BPA top face .. 57 Figure 29 Close-up of cracks at the west side of diaphragm II on 3/13/2018, by BPA .. 58 Figure 30 Notice the depth and width of diagonal cracks at the west side of diaphragm II on 3/14/2018 by 59 Investigation of March 15, 2018 Pedestrian Bridge Collapse at Florida International University, Miami, FL 5 Figure 31 Notice the depth and width of cracks near column 12 at the west side of diaphragm II on 3/14/2018 by 60 Figure 32 Cracks at the construction joint of the main span deck and diagonal 11 on 3/13/2018 by BPA .. 61 Figure 33 Cracks at the construction joint of the main span deck and diagonal 11 on 3/13/2018 by BPA.

5 62 Figure 34 Cracks at the construction joint of the main span deck and diagonal 11 on 3/13/2018 by BPA .. 63 Figure 35 Cracks at the construction joint of the main span deck, diagonal 11 and the chamfer of diagonal 11 on 3/13/2018 by BPA .. 64 Figure 36 Cracks at the construction joint of the main span deck and diagonal 11 on 3/13/2018 by BPA .. 65 Figure 37 Cracks at the construction joint of the main span deck and diagonal 11 on 3/13/2018 by BPA .. 66 Figure 38 Cracks at the construction joint of the main span deck and diagonal 11 on 3/13/2018 by BPA .. 67 Figure 39 Close-up of longitudinal cracks in diagonal 11 on 3/14/2018 by BPA .. 68 Figure 40 Close-up of longitudinal cracks in diagonal 11 on 3/13/2018 by BPA .. 69 Figure 41 Close-up of longitudinal cracks in diagonal 11 on 3/13/2018 by BPA .. 70 Figure 42 Cracks at the west side of diaphragm II on 3/14/2018 by BPA .. 71 Figure 43 Cracks at the east side diaphragm II on 3/10/2018 top face, by 72 Figure 44 Cracks and movement of the column at the east side of diaphragm II on 3/14/2018 by BPA.

6 73 Figure 45 Note the gap indicative of movement between sleeve pipe and concrete, pictured on 3/13/2018 by 80 Figure 46 Bridge immediately prior to the Collapse , March 15, 2018 camera #1 .. 85 Figure 47 Bridge immediately after the Collapse , March 15, 2018 camera #1 .. 86 Figure 48 Bridge immediately prior to the Collapse , March 15, 2018 camera #2 .. 87 Figure 49 Bridge immediately after the Collapse , March 15, 2018 camera #2 .. 88 Figure 50 Bridge immediately prior to the Collapse , March 15, 2018 camera #3 .. 89 Figure 51 Bridge immediately after the Collapse , March 15, 2018 camera #3 .. 90 Figure 52 Column 12, diagonal 11 and part of the canopy after Bridge deck and diaphragm fell to the ground, March 17, 2018, by OSHA .. 91 Figure 53 Northernmost blister and hydraulic jack attached to the lower PT bar of diagonal 11 after Bridge Collapse side view, March 17, 2018 by OSHA.

7 91 Investigation of March 15, 2018 Pedestrian Bridge Collapse at Florida International University, Miami, FL 6 Figure 54 Northernmost blister and hydraulic jack attached to the lower PT bar of diagonal 11 after Bridge Collapse front view, March 17, 2018 by OSHA .. 92 Figure 55 Northernmost blister and pressure gauge, March 17, 2018 by OSHA .. 92 Figure 56 Hydraulic pump for post-tensioning after Bridge Collapse , March 17, 2018 by OSHA93 Figure 57 Lower PT separated from the diagonal 11 still embedded in diaphragm after Bridge Collapse , March 17, 2018 by OSHA .. 93 Figure 58 Concrete blow-out failure in Diaphragm II at the time of Bridge Collapse at the site looking north from south, March 21, 2018, by OSHA .. 94 Figure 59 Concrete blow-out failure in Diaphragm II at the time of Bridge Collapse at the site looking north from south, March 21, 2018, by OSHA .. 94 Figure 60 Concrete blow-out failure in Diaphragm II at the time of Bridge Collapse at the site looking north from south, March 21, 2018, by OSHA.

8 95 Figure 61 Remnants of diaphragm II at the time of the Bridge Collapse in the storage yard looking north from south, April 9, 2018, by OSHA .. 95 Figure 62 Concrete blow-out failure in Diaphragm II at the time of Bridge Collapse in the storage yard looking north from south, April 9, 2018, by OSHA .. 96 Figure 63 Blow-out hole in Diaphragm II at the time of the Bridge Collapse in the storage yard looking north from south, April 9, 2018, by OSHA .. 96 Figure 64 Punched hole in Diaphragm II at the time of the Bridge Collapse from south looking towards north, April 9, 2018, by OSHA .. 97 Figure 65 Punched hole in Diaphragm II at the time of the Bridge Collapse from south looking towards north, April 9, 2018, by OSHA .. 97 Figure 66 Punched hole in Diaphragm II at the time of the Bridge Collapse from south looking towards north, April 9, 2018, by OSHA .. 98 Figure 67 Punched hole in Diaphragm II at the time of the Bridge Collapse from south looking towards north, April 9, 2018, by OSHA.

9 98 Figure 68 Punched hole in Diaphragm II at the time of the Bridge Collapse from south looking towards north, April 9, 2018, by OSHA .. 99 Figure 69 Punched hole in Diaphragm II at the time of the Bridge Collapse from south looking towards north, April 9, 2018, by OSHA .. 99 Figure 70 Punched hole in Diaphragm II at the time of the Bridge Collapse from south looking towards north, April 9, 2018, by OSHA .. 100 Figure 71 Side view of the saved portion of the diaphragm II in storage yard, April 9, 2018, by OSHA .. 100 Figure 72 Aerial view of the collapsed Bridge , March 15~18, 2018 .. 101 Figure 73 South end of the Bridge after Collapse looking 101 Figure 74 South end of the Bridge after Collapse looking east .. 102 Investigation of March 15, 2018 Pedestrian Bridge Collapse at Florida International University, Miami, FL 7 Figure 75 Vehicles crushed by falling Bridge .. 102 Figure 76 Overview of the main span truss system model.

10 105 Figure 77 Construction joint detail at diagonal 11 and deck.. 106 Figure 78 Potential line of crack plan view .. 111 Figure 79 Potential Punching shear failure at north end plan view .. 112 Investigation of March 15, 2018 Pedestrian Bridge Collapse at Florida International University, Miami, FL 8 LIST OF TABLES Table 1 PT schedule Main span deck .. 30 Table 2 Truss member details Main span .. 33 Table 3 Main span PT pre-stressed dates deck and canopy .. 34 Table 4 Main span PT pre-stressed dates diagonal members .. 34 Investigation of March 15, 2018 Pedestrian Bridge Collapse at Florida International University, Miami, FL 9 1. Executive Summary: On March 15, 2018, at approximately 1:45 , a Pedestrian Bridge under construction in Miami, Florida, collapsed. One employee and five motorists were fatally injured, and another employee permanently disabled, when the Bridge fell as the motorists waited for the traffic light underneath the Bridge and as the employees were performing work activities on top of the Bridge structure.