Heavy Lifts Research Articles

Multiple Heavy Lifts Optimization

Heavy lift planning has a major impact on construction sequencing, scheduling, budgeting, and safety. This paper addresses problems presented by planning for multiple lifts on a single jobsite. This is a common and particularly challenging planning situation because of the complex trade-offs involved. Conventional intuitive planning procedures lead to sub-optimal plans or plans ranked with little quantitative or objective measure. This paper first introduces various factors affecting planning decisions for multiple heavy lifts and then presents an interactive computer-aided process to optimize initial crane configurations and placement locations for multiple lift problems. In the computer-aided planning process, the minimal number of equipment relocations is determined based on an integer programming model, and the precise equipment locations are optimized with an interactive procedure using objective performance functions. Objectives involve cost, safety, and area interference (area sterilization). These optimization procedures are implemented in the critical operations planning environment (COPE). A case study is used to demonstrate the optimization process. It is concluded, based on a case study and external reviews, that the process and algorithms presented help produce good plans for multiple heavy lifts on construction sites.

Quantitative intramuscular myoelectric activity of quadratus lumborum during a wide variety of tasks

Intramuscular fine-wire electrodes monitored the electromyographic activity of quadratus lumborum in four young adults. A wide variety of tasks were performed including flexion tasks, lateral bending, twisting, extension, and lifting tasks. Heavy lifts of barbell weights up to 70 kg activated the quadratus lumborum 74% of their maximum on average while surface recording of erector spinae (L 3) were only 62% of their maximum activation. The quadratus lumborum was more active (54%) than other muscles during isometric side support postures where the body is held horizontally almost parallel to the floor as the subjects supported themselves on one elbow on the floor together with both feet. Furthermore, it increased activation in response to increasing compression in static upright standing postures.

Work activities and musculoskeletal complaints among preschool workers

The potential for musculoskeletal trauma among preschool workers has been largely unexplored in the United States. This case report describes an investigation conducted to identify and evaluate possible causes of back and lower extremity pain among 22 workers at a Montessori day care facility. Investigators met with and distributed a questionnaire to school employees, and made measurements of workstation and furniture dimensions. Investigators also recorded the normal work activities of school employees on videotape, and performed a work sampling study to estimate the percentage of time employees spend performing various tasks and in certain postures. Questionnaire results from 18 employees indicated that back pain/discomfort was a common musculoskeletal complaint, reported by 61% of respondents. Neck/shoulder pain, lower extremity pain and hand/wrist pain were reported by 33, 33 and 11% of respondents, respectively. Observation and analysis of work activities indicated that employees spend significant periods of time kneeling, sitting on the floor, squatting, or bending at the waist. Furthermore, staff members who work with smaller children (i.e. six weeks to 18 months of age) performed more lifts and assumed more awkward lower extremity postures than employees who work with older children (3–4 years of age). Analysis of two lifting tasks using the revised NIOSH lifting equation indicated that employees who handle small children may be at increased risk of lifting-related low back pain. Investigators concluded that day care employees at this facility are at increased risk of low back pain and lower extremity (i.e. knee) injury due to work activities that require awkward or heavy lifts, and static working postures. Recommendations for reducing or eliminating these risks by modifying the workplace and changing the organization and methods of work are presented.

Dual Use of Heavy Lift Ships as Maintenance Platforms and Transports for Mine Warfare Ships

ABSTRACTToday, the U.S. Navy is faced with world‐wide requirements for Mine Countermeasure Ships (MCMs). The size and propulsion characteristics of these ships make “heavy lifting” around the world a viable option. The heavy lift method of ship transport has been used successfully in the past for ships of this class. During the Gulf War (1990–1991), the U.S. Navy determined the fastest and most efficient way to transport Mine Warfare ships to and from the Arabian Gulf was via a Dutch heavy lift ship. This mode of transport affords a drydocking opportunity, where critical pre‐ or post‐deployment underbody maintenance can be completed. The heavy lift ship provides a potential in‐theater docking platform asset for emergent underbody work to be performed while the ship is in transit. This paper describes in detail previous heavy lift experiences, including specifics regarding capabilities, limitations, and lessons learned. It also discusses the feasibility for future heavy lifts for up to four MCMs.

The optimal training load for the development of dynamic athletic performance

This study was performed to determine which of three theoretically optimal resistance training modalities resulted in the greatest enhancement in the performance of a series of dynamic athletic activities. The three training modalities included 1) traditional weight training, 2) plyometric training, and 3) explosive weight training at the load that maximized mechanical power output. Sixty-four previously trained subjects were randomly allocated to four groups that included the above three training modalities and a control group. The experimental groups trained for 10 wk performing either heavy squat lifts, depth jumps, or weighted squat jumps. All subjects were tested prior to training, after 5 wk of training and at the completion of the training period. The test items included 1) 30-m sprint, 2) vertical jumps performed with and without a countermovement, 3) maximal cycle test, 4) isokinetic leg extension test, and 5) a maximal isometric test. The experimental group which trained with the load that maximized mechanical power achieved the best overall results in enhancing dynamic athletic performance recording statistically significant (P < 0.05) improvements on most test items and producing statistically superior results to the two other training modalities on the jumping and isokinetic tests.

Computer‐Aided Planning for Heavy Lifts

This article presents research into automating some lift planning practices common to industrial construction contractors and owners. A detailed investigation of heavy-lift planning methods was conducted through a series of interviews and lift studies with expert lift planners. This investigation documented a wide variety of manual and computer-aided lift planning methods to perform similar types of planning tasks. Based on the information collected from these interviews and lift studies, a structured systems model was developed of the typical heavy-lift planning process. This structured model is used as an architecture for the development of computer software to aid key planning tasks. An examination of major planning tasks indicates that significant reductions in direct planning costs and indirect construction heavy-lift costs are possible through the implementation of computer-aided planning procedures. Computer-aided procedures would also improve the overall quality of lift planning practices through the automation of tasks which are difficult to perform and are critical to heavy-lift planning accuracy.

Shipboard Damaged Stability Assessment: The Flooding Casualty Control Software

ABSTRACTThe Flooding Casualty Control Software (FCCS) was developed under the auspices of the Naval Sea Systems Command (NavSea) and is currently being deployed on a variety of ships in the fleets of both the U.S. Navy and the U.S. Coast Guard. The primary objective of FCCS is to enable damage control personnel to identify critical stability conditions, especially when related to the loss of reserve buoyancy due to battle damage and the destabilizing effects of large quantities of firefighting water, in a timely manner.FCCS was initially deployed in 1990. It utilizes the standard algorithms of the Ship Hull Characteristics Program (SHCP). The user interface was designed to allow quick familiarity for shipboard users, primarily the damage control assistant (DCA) and his staff. Intact stability evaluations include the effects of topside icing, high winds, personnel crowding, heavy lifts over the side, high speed turns, and towing. FCCS also supports ballasting analysis for amphibious ships as well as providing bottom reaction and beached stability data for grounding incidents. By providing a tool for the “fuel king” and DCA to generate the required daily updates on the current ship load and liquids status, FCCS is assured of an accurate baseline in the event of damage. The design allows the evaluation of the ultimate ship stability status for a damage event using simple compartmentation and flooding status inputs. Evaluation of the adequacy of resulting stability, as well as identification of such critical stability parameters as off center loading, margin line immersion, and negative GM, are accomplished by the program. Guidance is provided for the user to initiate appropriate flooding related damage control activities.Initially fitted on USS Oliver Hazard Perry Class frigates, FCCS databases have been for the USCG Hamilton class high endurance cutters, USS Arleigh Burke class Aegis destroyers, and a variety of other U.S. Navy and U.S. Coast Guard ship classes. The program accommodates such special features as well decks, compensating fuel systems, and a variety of evaluation criteria. FCCS is currently configured for use as a non‐integrated backfit to existing ships. Development efforts are underway in parallel to provide FCCS as a module for the Integrated Survivability Management System (ISMS).

Lumbar posterior ligament involvement during extremely heavy lifts estimated from fluoroscopic measurements

The mechanical role of the lumbar posterior ligaments during lifting tasks remains controversial. This study was designed to assess the ligament and disc contribution in resisting trunk flexion moment during extremely heavy lifts performed by national class powerlifters. Direct measurements of lumbar vertebrae kinematics in sagittal plane were obtained from videofluoroscopy utilizing multiple digitizing, correction for optical distortions and digital filtering. Four experienced powerlifters executed three trials, resulting in about 72 mA s of total radiation exposure. In the first trial, joint angles were measured when subjects fully flexed their spines to a point where the passive tissues resisted the flexor moment creating myoelectric silence in the extensor musculature. Next, two conventional deadlift style lifts were executed with the barbell load ranging from 183.7 to 210.9 kg. Four vertebral corners were digitized at a sampling rate of 30 Hz. The relative intervertebral joint angles, distance between the ligament attachment points, shearing and compressive displacements were calculated from a rigid body motion approach. Analysis revealed that except for one trial of one subject, they accomplished their lifts with an amount of lumbar flexion between 1.5 and 13° less than they demonstrated during full flexion. Resultant ligament lengths at the beginning of the lifts ranged from 56.1 to 99.8% of their lengths when the trunk was fully flexed. It was concluded that ligaments did not strain sufficiently to contribute substantial resistance to the trunk flexion moment, relegating this responsibility to the musculature.

Reassessment of the role of intra-abdominal pressure in spinal compression.

Biomechanical models used to estimate loads on the lumbar spine often predict internal low back forces for heavy lifts that exceed known tissue tolerances, yet the particular lift caused no apparent damage to the lifter. To deal with this paradox, many researchers have incorporated some form of spinal compression alleviation from intra-abdominal pressure (IAP). The purpose of this work was to re-examine some of the issues involved in the feasibility of IAP to reduce spinal loads during stressful lifts. Questions remain over the trade-off between the beneficial tensile force on the spine, exerted via the diaphragm and pelvic floor when IAP is produced, and the undesirable compressive effects of abdominal muscular force required to maintain the pressure within the abdomen. Various strategies of modelling IAP and its effects on low back loading were employed, Three major differences between this and most previous models of IAP effects were the attempt to quantify the size of abdominal muscle forces and the u...

Low back strain in Danish semi-skilled construction work

Danish semi-skilled construction workers (SC-workers) perform a variety of tasks in building construction, civil engineering and rebuilding. A previous epidemiologic study indicated a high occurrence of low back pain (LBP) among these worksers. The study was designed to quantify the major occupational risk factors associated with the development of LBP, i e, inclined postures, repetitive movements, heavy lifts, pushing/pulling motions, sudden unexpected strains and whole body vibrations in this group of construction workers. Firstly a study of occupational activity of 112 SC-workers on height construction sites during two separate five-days periods was carried out. This was followed by an observational study of the nine work tasks most common to SC-workers. Heavy lifts, pushing/pullin motions and sudden unexpected strain occurred most frequently in the work, while inclined postures, repetitive movements and whole body vibrations characterised different parts of the work. Assessments of the strain were made on the basis of techniques given in the literature.

Hydrodynamic Winch for Salvage Operations

Lifting or lowering of very heavy loads in the ocean (1000 tons or more) from any depth under controlled conditions has proven to be very difficult. Lifting very heavy loads from great depths using the present winching or lifting methods is for practical purposes nonexistent. Pontoons and winches have been used for limited loads and limited depths. The problem of breakout forces, buoyancy controls, dynamic wave induced cable stresses, etc., have made very heavy lifts from the ocean depths almost impossible to perform. The Hydrodynamic Winch is a proposed solution to the very heavy undersea lift and control problem.