Construction laborer dies after falling off collapsed precast concrete floor slab.
NIOSH 2007 Aug; :1-14
In February 2007, an adult male construction laborer (the victim) sustained fatal injuries after falling off a collapsed precast concrete floor slab at a ten-story building construction site. A concrete floor slab was 26' (feet) 5½" (inches) long, 8'3" wide and 8" thick, and weighed approximately seven tons. The floor slabs were positioned on the building's steel structural frame composed of vertical steel columns and horizontal steel beams. The slabs were not secured to the steel framework at the time of the incident. At approximately 9:20 a.m., the victim and a co-worker were on the 6th floor using pry bars to adjust the precast floor slabs into their final positions before they were to be permanently secured to the steel framework. The southern section of the slab rested on the horizontal steel beams and its northern section was suspended (cantilevered) without the support of the steel beams. After the two workers finished adjusting the slab, they both walked northward on the slab near its east end. The slab suddenly tilted downward at its north side, rotated to a near vertical position, and became wedged in between the steel supports. The co-worker secured himself with his elbows onto the slab in front of him and climbed up. The victim fell to the floor below. The failed slab then fell, struck the victim, and crashed through the cement slab floors below. The victim fell through the opening created by the fallen slabs and landed on the 3rd floor. The co-worker immediately ran down to the victim and removed him from the collapsed zone. One of the workers called 911. Both police and an emergency service unit responded within minutes. The victim was transported to a hospital where he died an hour later. The post incident investigation found that a number of steel columns including the ones in the collapsed zone were erected out of plumb. The out-of-plumb columns led to increased spacing between the columns resulting in reduced beam support for the slabs located in-between these columns. The integrity of the initially failed slab was further compromised by its notched shape and cantilevered section. New York State Fatality Assessment and Control Evaluation (NY FACE) investigators recommend the following measures to help prevent similar incidents from occurring in the future, employers should: 1.) comply with the structural dimensions and tolerances specified by the erection design and check vertical and horizontal alignment of the steel structural frame before erecting any precast slabs; 2.) ensure that workers use personal fall protection arrest systems when working on the precast concrete floor slabs that are not permanently secured to the steel framework; 3.) provide employees with training on the prevention of fall hazards associated with working on the unsecured precast concrete floor slabs; and secure the precast slabs to the steel structural frame by the method specified in the erection plan as soon as the slabs are erected. Additionally: 4.) the integrity and support strength of odd shaped or notched precast concrete members should be carefully evaluated; supplemental fastening should be provided if necessary. 5.) quality control procedures should be implemented to ensure that proper tolerances are maintained by all trades involved in a precast concrete construction project. 6.) pre-construction meetings should be held to clearly define the responsibilities of all key participants of a precast concrete construction project.
Region-2; Accident-analysis; Accident-prevention; Accidents; Injuries; Injury-prevention; Safety-education; Safety-equipment; Safety-measures; Safety-monitoring; Safety-practices; Safety-programs; Training; Traumatic-injuries; Work-analysis; Work-areas; Work-operations; Work-performance; Work-practices; Concretes; Construction; Construction-industry; Construction-workers; Engineering; Personal-protection; Personal-protective-equipment; Protective-equipment;
Author Keywords: precast concrete; floor slab; tolerances; multistory building; construction; fall; crushed by; steel structural frame
Field Studies; Fatality Assessment and Control Evaluation
NTIS Accession No.
National Institute for Occupational Safety and Health
New York State Department of Health. Health Research Incorporated