Cranes for Building Construction Projects

Cranes have come to symbolize building construction itself. They perform indispensable services in moving materials and components vertically and horizontally. Used since antiquity, their history is interrelated with the development of new power sources that replaced man and mule, first steam and later internal combustion, diesel, and electric engines. Mobile cranes can be rapidly deployed to lift heavy loads. New models with telescoping booms and all-terrain travel capability, compact urban machines, and even hybrids with tower cranes are beginning to replace the familiar lattice boom truck cranes. Mobile cranes have dominated the North American market, but a cultural change appears to be taking place toward tower cranes for building projects. Tower cranes, common in Europe for decades, are globally gaining in popularity with surging real estate developments. Ideal for dense urban environments and coming with a small footprint, they are available in a growing diversity of sizes and configurations. Sophisticated electronic controls and operator assistance devices are enhancing their safe and productive operation. While cranes occupy a central role on midrise and high-rise building projects, they operate in conjunction with other types of supporting equipment that are an essential part of the overall equipment array on today’s industrialized construction sites.     

Vision System for Tower Cranes

Operators of tower cranes enjoy a bird’s eye view of the site, which undeniably contributes to work safety and efficiency. Yet their work often involves blind lifts, as well as other viewing difficulties, that impede full utilization of the potential inherent in the operator’s location atop the crane. This paper reports on a tower-crane-mounted live video system that offers a solution for such difficulties, and consequently, enhances safety, improves productivity, and brings about direct and indirect cost savings. The development and implementation of the vision system are described as a successful academia–industry research and development joint effort. Work studies of numerous craning cycles resulted in considerable time savings, depending on the nature of the lift, lighting conditions, and viewing obstructions. In addition, a detailed list of benefits drawn on the basis of feedback received from the field is presented. The paper is aimed, first and foremost, at project managers as well as construction equipment and safety practitioners, who daily experience those situations that have prompted the development of the system. Researchers may benefit mainly from the lessons learned with respect to the role of academia–industry cooperation in the introduction of innovative systems in construction.     

Computational Methods for Coordinating Multiple Construction Cranes

The incremental coordination method a computational method for preplanning and coordinating the use of multiple tower cranes in relatively narrow construction sites is presented. The incremental coordination method considers the kinematics and the geometrical constraints of cranes to plan the motion of two or more cranes, which are being operated in collaboration. By following such planned motions, erection tasks are completed safely, even when the cranes are operated in close proximity of each other. This method allows the use of computers to plan and coordinate the crane activities from start to end of an erection process. This paper also explains the computational methods required by the incremental coordinate method including path-finding and collision detecting methods. An example case shows two construction cranes, each of three degrees-of-freedom, operating together on a building project where the working areas of the cranes intersect, hence possibility colliding with each other. A numerical test was conducted to verify the efficiency and effectiveness of applying the incremental coordination method in planning and synchronizing all motions of the two cranes to avoid any collision between the cranes themselves and collision with obstacles on the construction site.     

Interactive and Dynamic Integrated Module for Mobile Cranes Supporting System Design

Analyzing and designing a crane supporting system can be time-consuming process. In particular, the dynamic nature of mobile crane operations entails a variety of reaction values for truck and crawler cranes. The platform of a mobile crane can either be set on outriggers—denoted as a truck crane, or on a crawler tracks—denoted as a crawler crane. Designing of a mobile crane supporting system depends on the lifting configuration, type of crane and the type of materials to be used under the crane outriggers or crawler tracks. This paper presents an automated system which is designed to assist practitioners in calculating the mobile crane’s support reactions and in designing the supporting system. This system is developed such that it can generate a 2D reaction influence chart which shows the reactions for each outrigger at varying horizontal swing angles and vertical boom angles to the ground. Most of the geometric configurations needed to perform the support design are not ordinarily given in crane manufacturer’s manual and to address this deficiency, this newly developed system has been integrated with a previously developed crane database which contains information on widely used mobile cranes for construction along with a crane selection system. A case example is described in order to demonstrate the use and effectiveness of the presented system in automating crane lift analysis.     

Simulation-Based Identification of Possible Locations for Mobile Cranes on Construction Sites

Identifying spatial-conflict free locations of mobile cranes that could minimize delays associated with crane relocation can result in productivity and safety improvements on construction sites. Existing approaches for identifying possible crane locations are based on two-dimensional (2D) work envelopes created by reasoning about the lift capacities of a crane during operations. Since spatial conflicts related to crane operations typically occur in three dimensions and during any period of operation, representing possible crane locations based on such 2D work envelopes can result in identifying some locations as good when in fact they might result in conflicts and missing possible locations that might be feasible. This paper presents an approach that determines possible locations of mobile cranes based on discrete-event simulation of crane operations incorporating dynamic behaviors of cranes. This approach starts with identifying a search space for possible crane locations by reasoning about a reachability radius of a crane determined by crane characteristics and the weight of the load to be carried. Later, it reduces the search space through boom-line intersection tests. For the remaining locations, it checks for potential spatial conflicts between building components and cranes moving in three dimensions and across time. Validation studies show that the developed approach can accurately identify possible locations for mobile cranes that minimize the relocation of mobile cranes and avoid potential spatial conflicts.     

Lampson Transi-Lift Mobile Crane: Concept, Design, and Use

The Lampson Transi-Lift mobile crane is a lifting system purposely designed for construction activities related initially to nuclear power facilities. The combination of capacity, increased working hook height, and an unmatched radius to capacity ratio allowed for use of innovative construction techniques that decreased the construction schedule, increased facility integrity and construction safety, and reduced overall plant construction costs. The versatility of the Lampson Transi-Lift was immediately recognized, and it has become a mainstay of the heavy lift industry since its introduction in the late 1970s. Oil and gas, general construction, and offshore construction activities have all since benefitted from the unique capabilities of this heavy lift crane     

Optimization Algorithm for Selection and on Site Location of Mobile Cranes

Mobile crane manufacturers provide operators and practitioners with tabulated lift-capacity charts. These charts are structured based on predetermined crane configurations, which consist of boom/jib length, lifting radius, lifting height, main boom angles to ground, and jib angle to ground or its offset to its main boom centerline. Practitioners, however, are often required to lift on a partially extended hydraulic section and/or lifting radius other than those listed in the manufacturers’ lift-capacity charts. This paper presents a newly developed optimization algorithm (referred to in this paper as Algorithm-2) for selecting and locating mobile cranes on construction sites based on their minimum boom length and/or minimum radius, accordingly higher lifting capacities. Algorithm-2 includes an optimization procedure that avoids lifting capacity violations. In addition to the practical use of Algorithm 2, the mathematical representations of the crane’s geometry are also useful for research in the automation and robotic field of operations involving cranes. The algorithm is incorporated into a computer system that integrates a selection module and a database. Data pertinent to crane lift configurations are retrieved from the database and are then processed to determine the optimum, geometrical selection of the crane configuration. A case example is described in order to demonstrate the use of the developed algorithm and to illustrate its essential features.     

“Soft” Considerations in Equipment Selection for Building Construction Projects

This paper raises the issue of “soft” considerations in the selection of equipment for building construction projects. The paper aims at increasing the awareness: (1) to the nature, variety, and richness of soft factors; (2) to their significant role and potential impact on the outcome of decision making; and (3) to the inherent difficulty of evaluating them and integrating them within a comprehensive selection process. Existing state-of-the-art equipment selection models were analyzed and found to be inadequate in terms of both considering soft factors and providing mechanisms for their systematic evaluation. Six cases of large-size, complex construction projects were investigated to obtain an extensive list of typical soft factors. This investigation revealed that the consideration of soft factors in current practices is essentially unstructured and is not integrated within the selection process in a systematic manner. A desirable selection process is outlined that generally responds to the needs identified in the study. The proposition of a specific method for the quantitative treatment of soft factors and their tradeoff with cost factors is the subject of another paper.     

Nonlinear Models for Predicting Hoisting Times of Tower Cranes

Accuracy in estimating activity duration is one of the key prerequisites for successful construction planning. Efficient material transportation plays an important role in reducing costs and time. Time measurement and work-study techniques can provide good estimation of activity duration, but forming the databank for various conditions is expensive. The use of empirical models has been developed as an alternative to overcome the deficiency while maintaining a reasonable accuracy. In this research traditional linear regression models and nonlinear neural network models have been developed for predicting hoisting times of a tower crane. It is found that nonlinear neural network models can achieve higher accuracy. However, planners may find that the regression models, which describe the relationship between the variables in more simplistic terms, could allow them to shorten the hoisting times by manipulating the input variables. The results and the merits of the models are discussed.     

Automated Path Planning of Cooperative Crane Lifts Using Heuristic Search

The use of cooperative cranes can improve the cost effectiveness of heavy lift operations. However, the complexity in developing a reliable lift plan prevents the widespread use of cooperative crane lifts. The availability of a computer-aided planning system can improve planning efficiency and reliability. Path planning is an important subtask of the lift planning process. This paper presents work done to develop a computer aided path planner for two crane lifts. Two heuristic search methods, hill climbing and A?, were implemented for automating the path-planning task. Search space was represented using the concept of configuration space. The effectiveness of the search methods was evaluated by solving three problems with increasing levels of complexity. The formulation of these problems was based on the type of movement of cooperative cranes (in synchronous or asynchronous manner) and the presence of trapping space. It was found that while the hill climbing approach found feasible paths in a few seconds or minutes, these paths were far from optimal in situations containing trapping space. In contrast, the A? search resulted in near optimal paths, but the execution time was of the order of hours.     

Collision Free Path Planning of Cooperative Crane Manipulators Using Genetic Algorithm

This paper presents a new approach for automated path planning of cooperative crane manipulators using a genetic algorithm (GA). The inverse kinematic problem, i.e., determining the joint angle configuration for the cooperative crane manipulator system in moving the object from pick location to place location, is defined as an optimization problem and solved using GA. For generating the collision-free path, GA with an interference detection algorithm is employed and search is made in the manipulator joint angle space (configuration space). The effectiveness of the proposed approach for automated path planning is demonstrated by comparing the performance of the present approach with the earlier heuristic search proposed by Sivakumar et al. The GA approach finds a near-optimal path with lower path cost and less computational time than earlier heuristic searches.     

AHP-Based Weighting of Factors Affecting Safety on Construction Sites with Tower Cranes

Aspiring to adopt a nonstatistical quantitative approach to safety assessment, this study implements a multiattribute decision-making tool to elicit knowledge from experts and formalize it into a set of weighted safety factors. The environment addressed is the construction site and the specific factors studied are those affecting safety due to the operation of tower cranes. Nineteen senior construction equipment and safety experts were interviewed and led through the analytic hierarchy process (AHP) to provide their assessments on the relative importance of safety factors obtained in an earlier study. The results accentuate the dominance of the crane operator and general superintendent on the site safety scene and play down the contribution of “classic” site hazards such as power lines. Quantitative measuring of safety, such as reflected in the weights obtained in this study, is important in communicating safety requirements and focusing the limited resources available for safety improvements. These factor weights are also deemed to be a vital component in the development of a comprehensive model that will allow the computation of safety indices for individual construction sites employing tower cranes. It is expected that the methodology can then be adopted for addressing other site safety issues as well.     

Feasibility of Automated Monitoring of Lifting Equipment in Support of Project Control

One of the differences between industrial manufacturing or processing plants and construction sites is the temporary nature of the construction site, which has traditionally precluded installation of sophisticated production monitoring systems. Monitoring of production progress, cost, and quality is performed almost exclusively manually, with the result that it is expensive and approximate, and is commonly delivered with a time lag that does not allow for an effectively closed control loop. Automated monitoring of construction lifting equipment to provide useful feedback information for project management is a strong potential candidate; almost all components and materials must be transported by machines, and monitoring of machines is relatively straightforward. A system concept, employing a “black box” monitor and an electronic building information model, was developed. A field study was conducted to test the feasibility of the concept. The results indicate that the system is technically feasible, and offers the potential to deliver real-time, accurate project control information at very low cost.     

Identification and Analysis of Factors Affecting Safety on Construction Sites with Tower Cranes

Tower cranes are the centerpiece of production on today’s typical building construction sites. Tower cranes hoist and transport a variety of loads near and above people, working under crowded conditions, occasionally with overlapping work zones, and often under time, budget, and labor constraints. This work regime further increases the safety risk on sites that are inherently hazardous workplaces. This paper presents the results of a study that identified the major factors affecting safety in tower-crane environments and evaluated the degree to which each factor influences ongoing safety on site. Use of statistical data on accidents was ruled out as a source of information due to the countless number of incidents that go unreported, the common inability of statistics to provide root causes, and the questionability of statistics as a predictor of accidents. The research methodology was therefore based on comprehensive questioning of an expert team that included the safety managers and equipment managers of leading construction companies. With the limited resources available for safety improvement and accident prevention, greater attention must be paid by all parties involved to those factors evaluated as highly affecting site safety due to tower-crane work.     

Analyses of Instability in Mobile Cranes due to Ground Penetration by Outriggers

This study focuses on the phenomenon of ground instability causing mobile cranes to overturn. Four outriggers usually support a mobile crane in order to restrict pitching during hoisting operations. Nevertheless, the crane may become quite unstable if the outriggers should happen to sink into the bearing ground. In this paper, various types of analysis, including experiments, were performed in order to investigate the influence of ground penetration by outriggers on the stability of mobile cranes. Through study of the results of experimentation and simulation, it has been clarified that mobile cranes become highly unstable as a result of rapid penetration. It was found that an index of relative instability had a linear relationship to the common logarithm of an index for brittle failure as derived from the load–settlement curve for ground penetration. Finally, a method of evaluating the risk of mobile-crane overturning is proposed by using the maximum value of both the supporting surface’s failure risk and the kinetic risk due to ground penetration.     

Dynamic Analysis of Tower Cranes

Tower cranes are widely used in the construction of high-rise buildings and the analysis of their dynamic behaviors is of both theoretical and practical significance. A parameterized super element formulation for modeling the multiple-pulley cables in a crane system is proposed based on the friction-free assumption between the cable and pulleys. The cable passages over intermediate pulleys are considered as new degrees-of-freedom in the proposed element model and equal tensions at different segments of a continuous cable are exactly achieved. Numerical results show that these cable passages have significant effect on both static tensions and dynamic properties of tower cranes and the proposed super element model provides more accurate and realistic results in dynamic analyses of the crane system. It is found that some modes are insensitive to the change of jib angle or bracings at crane mast, while others change drastically depending on the mode shapes. Picking up the payload from ground or payload accelerating/decelerating during lift operation will induce finite impulsive excitations and, therefore causes noticeable dynamic responses of the crane system.     

Building Integrated Architecture/Engineering/Construction Systems Using Smart Objects: Methodology and Implementation

Integrated project systems hold the promise for improving the quality while reducing the time and cost of architecture/engineering/construction (AEC) projects. A fundamental requirement of such systems is to support the modeling and management of the design and construction information and to allow the exchange of such information among different project disciplines in an effective and efficient manner. This paper presents a methodology to implement integrated project systems through the use of a model-based approach that involves developing integrated “smart AEC objects.” Smart AEC objects are an evolutionary step that builds upon past research and experience in AEC product modeling, geometric modeling, intelligent CAD systems, and knowledge-based design methods. Smart objects are 3D parametric entities that combine the capability to represent various aspects of project information required to support multidisciplinary views of the objects, and the capability to encapsulate “intelligence” by representing behavioral aspects, design constraints, and life-cycle data management features into the objects. An example implementation of smart objects to support integrated design of falsework systems is presented. The paper also discusses the requirements for extending existing standard data models, specifically the Industry Foundation Classes (IFC), to support the modeling of smart AEC objects.     

Interactive 3D CAD for Effective Derrick Crane Operation in a Cable-Stayed Bridge Construction

The high expectation of esthetic and functional quality in modern civil infrastructure has resulted in the increased demand for long span bridges. In advanced or developing countries, long span bridges such as cable-stayed and suspension bridges are considered even as landmarks that symbolize the prosperity or culture of the region. These long span bridges require higher level of design and construction technologies than other types of bridges. In particular, the construction of cable-stayed bridges involves precise and sophisticated operation of construction equipment such as derrick cranes. However, it is not easy to plan the operations of a derrick crane before the actual construction process takes place. Unexpected spatial constraints in the construction site may hinder the smooth operation of a derrick crane, which leads to lower than expected productivity and safety. This study applies interactive three-dimensional (3D) computer aided design (CAD) to the derrick crane operation for the purpose of identifying potential problems. Construction managers can have the two way process with the 3D CAD system to interactively test their construction plans and scenarios. The case study shows that the interactive 3D CAD system significantly improves the constructability of the cable-stayed bridge construction.     

Information System for Building Products

In a building process that enables a proper flow of product information among the “Users of Information” (Agents), a “Product Information System” is proposed. The system established in connection with a set of criteria involves five subsystems (Thesaurus, Summarized Data, Manufacturers, Compatibility Tables, and Detailed Data) linked with each other. Agents looking for product information can enter the system through the subsystems Thesaurus or Manufacturers, and they can decide on the choice of appropriate products at the first stage (Summarized Data), whereby they can find access to the subsystem Detailed Data afterwards for the detailed information needed. The complete code presents a medium for a common language among the users of product information.