Integrated Building Information Model to Identify Possible Crane Instability caused by Strong Winds

Transcription

1 1281 Integrated Building Information Model to Identify Possible Crane Instability caused by Strong Winds Shafiul Hasan 1, Hamid Zaman 2, Sanghyeok Han 3, Mohamed Al-Hussein 4 and Yi Su 5 1 Ph.D. Candidate, Construction Engineering and Management, Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta, T6G 2G7, Canada. mdshafiv@ualberta.ca 2 Ph.D. Student, Construction Engineering and Management, Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta, T6G 2G7, Canada. hzaman@ualberta.ca 3 Ph.D. Student, Construction Engineering and Management, Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta, T6G 2G7, Canada. sanghyeo@ualberta.ca 4 Ph.D., P.Eng., Professor, Construction Engineering and Management, Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta, T6G 2G7, Canada. malhussein@ualberta.ca 5 Ph.D. Student, Construction Engineering and Management, Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta, T6G 2G7, Canada. ysu6@ualberta.ca KEY WORDS: BIM, Stability, Wind, Crane Support Reactions, 3D Animation ABSTRACT Large scale construction projects often involve the lifting of heavy equipment. With increases in equipment size, lifting operations create new challenges in crane selection. In terms of safety, stability is one of the most important factors to consider when selecting cranes. Although practitioners often apply simulation tools to select appropriate cranes, the effect of wind on crane stability is not yet considered in the selection process. Considering that cranes are among the most expensive types of equipment, contractors need to plan the crane operations properly to improve safety and reduce cost and time. This paper presents a methodology to implement the safe operation of cranes by identifying possible crane instability caused by strong winds using Building Information Modeling (BIM), a tool which prepares smart designs to integrate and coordinate cross-disciplinary designs, the construction process, and facility management decisions. A methodology is proposed to integrate wind effects on crane operations which can be considered a major step in developing future BIM. Through a case study involving multiple heavy lifts in an industrial project, the benefits of the proposed methodology are identified. INTRODUCTION Building Information Modeling (BIM) is one of the most promising recent developments in the Architecture, Engineering and Construction (AEC) industry, where virtual digital models are created in order to facilitate project-related activities

2 1282 at various phases (Eastman et al., 2011). It allows better information sharing among the project stakeholders, and thus can improve safety, productivity, cost, schedule, and resource management for the project. BIM helps to facilitate a 3D visualization of the project to detect clashes or errors (Eastman et al., 2011). The traditional document-based project delivery method is archaic, error-prone, litigation-prone, high-risk, and reliant upon very inefficient, hard to predict construction processes that result in owners taking over projects with little information on how to operate and maintain their building (Neeley, 2010). The construction industry is seeking a new innovative approach to integrate all the information needed to describe buildings throughout the whole design, construction and management process. It is essential with the technology available today to improve the project delivery process. Building Information Modeling can be a major advantage to visualize, verify and validate lifting activities in large construction projects. In most countries, construction experiences the highest percentage of fatalities and either poor design or improper crane selection will contribute to most of the crane accidents on construction sites (Beavers et al. 2006). High wind speed affects the crane s lifting operations and creates safety hazards. One of the most devastating crane accidents, the Big Blue collapse on the Miller Park, was caused by wind (Ross et. al. 2007). However, considering the effect of wind on crane operations lift analysis is not widely practiced. Considering the effect of wind is not only important in terms of the instability of crane, but also in regards to the lift schedule, especially when the wind speed rises above the allowable limit set by crane manufacturers. A large construction project involves various inter-related activities where efficient resource sharing and utilization governs the success of the project. As such, BIM should contain all relevant information in a single model. There are a number of external factors (such as wind and snow) which affect the schedule of a project; however, most present models do not contain such information. Currently, BIM focuses mainly on: (1) laws and regulations, (2) material information and specifications, (3) procurement information, (4) facility information, (5) construction information, (6) simulation results, (7) 2D/3D drawings, and (8) visualization/animation models. This paper proposed to integrate weather information into BIM as weather affects the construction schedule (please see Figure 1). Figure 1. Proposed Building Information Model

3 1283 This study develops a methodology to incorporate historical wind speed data into lift analysis and simulation, from which crane support reactions are calculated during each lifting operation and stability is checked. Figure 2 presents the methodological flowchart adopted in this study. The proposed building information modeling comprises of the following three components: (1) wind analysis; (2) reaction calculations; and (3) visualization. Load - rigging and crane databases are employed here in order to retrieve the geometric information for the selected crane and lifted loads. The modeling process is based upon satisfying the following constraints: (1) lifting capacity; (2) lifting priority; (3) safety; (4) allowable ground pressure; and (5) allowable wind speeds. The outputs from the simulation and reaction calculation are then utilized to create 3D animation by using 3D Studio Max. The integrated model output includes the following four components: (1) forecast of wind speed and direction, based on historical weather data from the project location; (2) support reactions, which is determined by calculating the reactions for truck crane and tower crane, as well as the shapes and values of the track pressure for the crawler crane; (3) lifting schedule, which provides the detailed crane schedule satisfying the wind affects and ground pressure; and (4) 3D animation, which shows the lift activities with respective crane support reactions due to varying wind speeds and directions. Figure 2. Flow Chart of the Proposed Methodology BUILDING INFORMATION MODELING OF LIFTING OPERATIONS Figure 3 illustrates the logical flowchart of the proposed methodology, which integrates wind speed simulation and crane support reaction calculations with existing BIM. The proposed integrated model performs safety checks, simulates the lifting operations, and modifies project schedule accordingly. The first step involves sampling hourly wind speed and direction based on historical weather data from the project location. This sampled hourly wind data is used alongside lift activity duration data to perform simulation. The simulation model, developed using the Simphony.NET3.5 (Hazzar and AbouRizk, 1999) general purpose template, checks whether or not hourly wind speed is less than the allowable limit and either continues or suspends lift operation for the hour accordingly. The hourly wind data is also used

4 1284 to calculate the crane support reactions. The output from the simulation model is used to update the project lifting schedule. The proposed system also develops a 3D visualization model based on the simulation output, which is beneficial for error detections. Figure 3. Proposed BIM Logical Diagram Step 1: Sample Wind Speeds and Directions As every crane has a certain maximum allowable wind speed defined by the manufacturer, lifting activities can sometimes be affected by strong wind. According to crane manufacturers information on maximum allowable wind speeds, tower cranes have the advantage of usability in higher wind speeds (on average 9-14 m/s for mobile cranes compared to m/s for tower cranes). Using the daily average (or even maximum) wind speed data from the project location does not capture the true scenario. Thus, in this study, hourly historical weather data from the project location has been utilized to sample wind speed and directions at each hour during construction work. Monte Carlo simulation technique is utilized to sample wind speed and direction data for the project location. The simulation model for lifting activities is developed in Simphony.NET3.5 where the cranes are modeled as resources. Modeling the crane as a resource allows ceasing crane operation whenever the generated wind speed exceeds the maximum allowable limit. This captures the effect of wind speed on the project schedule. Then the simulation output, comprised of the start and finish times of various tasks for each lift (hook, lift object, swing, lower object, unhook, swing back), along with hourly wind speed and direction data is written to an external CSV file. This simulation output is utilized for two purposes: 1) calculation of the crane support reactions; and 2) animation of lifting activities using the forecasted weather (wind) data. Step 2: Support Reactions Calculations The types of mobile cranes available vary due to the different types of booms (telescoping or lattice) and undercarriages (on wheeled or crawler-tracked) used. To

5 1285 simplify the reaction calculation process, in this paper, mobile cranes have been classified into two categories: truck crane and crawler crane (see Figure 4). There are several methods of support for static mount tower cranes such as: in-situ anchor bolt base, in-situ expendable base, knee braced base, guyed tower crane with spread footing, braced tower crane and internal climbing crane. In this paper, tower cranes with four legs (anchor bolt) are considered for reaction calculations (see Figure 4). Figure 4. Crane Support Reactions The outriggers reactions and the track pressure or the tower crane s legs reactions are a function of the respective weights of the lift and crane components and their moments around the crane s centre of rotation. These moments are divided into two categories based on the horizontal and vertical movements of the boom; one acting around the crane sides M ns and the other acting on the crane rear or front M nr. These longitudinal and transverse moments are also affected by wind speed and direction. These moments are calculated satisfying Equations (1) and (2): M M sinα + M sin( α ω) (1) ns = u w M nr = M cosα + M cos( α ω) V x (2) u w u o where M u is the ultimate moment, M w is the moment created by the wind force, α is the horizontal swinging angle measured counter clockwise from North, ω is the direction of wind measured counter clockwise from North, V u is the total vertical load, and x 0 is the distance between the crane s centerline and the center of rotation. Total vertical load V u and ultimate moment M u are calculated satisfying Equations (3) and (4), respectively. V = W + W + W + W (3) u u load load aw aw sw sw cw M = M + M + M + M (4) where W load is the weight of the lifted load, W aw is the weight of the additional load for the slings and rigging, W sw is the weight of the crane structure, e.g. boom or tower, jib, or machine, W cw is the weight of the counterweight, M load is the moment created by the lifted load, M aw is the moment created by the additional loads, M sw is the moment created by the movement of boom, jib or structure, and M cw is the moment created by the counterweight. The wind moment (M w ) is the function of the wind velocity pressure. If the wind velocity is v then wind pressure (q) can be calculated satisfying Equation (5) (Shapiro et. al. 1999): cw

6 1286 5v 2 q = (5) 8 where v is in meters per second and q is in Newtons per square meter. The height or lift elevation is an important factor in this regard, since the wind speed is measured at 10 m above the ground. The Construction Plant-hire Association (2009) suggests wind speed multiplying factors (f) for lifting operations higher than 10 meters above the ground. Thus the wind pressure (q) can be calculated satisfying Equation (6): 5 2 v q = f (6) 8 when v is in meters per second and q is in Newtons per square meter. To simplify the wind moment calculation it is assumed that the surface of the boom or tower and jib is solid and rectangular. Therefore, resultant wind forces are calculated based on the surface area and wind pressure acting on that surface, e.g., wind force on boom (F b ) or tower (F t ), jib (F j ) and lifted load (F l ) (see Figure 5). Due to negligible surface area, wind pressure acting on crane rigging, gantry and other parts are neglected. Figure 5 presents the different steps for calculating wind forces for mobile cranes (5-a, 5-b) and tower cranes (5-c, 5-d). Wind moment (M w ) is calculated satisfying Equation (7): M = F. H + F. H + F. H (7) w b b where H b, H j and H l are the height of the resultant wind forces acting on the boom, jib and lifted load from the ground, respectively. j j l l Figure 5. Wind Acting on Mobile Crane: (a), (b), and Tower Crane: (c), (d) The reaction under the truck crane s four outriggers two fronts (P.Front1, P.Front2) and two rears (P.Rear1, P.Rear2); or the crawler crane track pressures under the track 1 (P.Front1, P.Rear1) and track 2 (P.Front2, P.Rear2) (see Figure 6) are calculated using the research of Hasan et. al (2010) and using the moments calculated satisfying Equations (1) to (7). For tower cranes with bolt anchorage support, the reactions for four legs are calculated using the same methodology as described for the truck crane in Hasan et. al (2010) and using the moments calculated satisfying Equations (1) to (7).

7 1287 Figure 6. Crane Reactions Wind direction plays an important role in calculating the support reactions. The effect of wind direction on crane support reactions can be displayed in a reaction influence chart, support reactions for 360 rotation of the crane for a particular boom angle and jib angle (Hasan et. al. 2010). Figure 7-a and 7-b present reaction influence charts for one crawler track pressure, P.Front1 (see Figure 6), at 13.9 m/s wind speed, and one tower leg reaction, P.Front1, at 20 m/s wind speed, respectively, at different wind directions and 360 rotation when the lifted load is 30 tons (the type of cranes used in these analyses are described in the case study section). If any reaction becomes negative, then it means tension force has developed on that support and it can cause possible crane tipping. Thus, to maintain crane stability all the support reactions should be positive and project manager needs to be aware of this to schedule crane operations safely and successfully. (a) (b) Figure 7. Wind Direction Effects on (a) Crawler, (b) Tower Crane Operations Step 3: Visualization Modeling The proposed methodology integrates the wind information (speed and direction) and support reaction with BIM which provides geographical data to decide crane positions and pathway, and the information of materials for lifting. The detailed information of the crane operation includes the process time of each activity such as hoist up, swing, travel, hoist down travel distance and swing degree. This information is generated in the simulation model and automatically extracted and stored in Microsoft Excel Based on information from BIM and simulation, 3D visualization is developed with wind information and support reaction in 3DS. The 3D model provides the information about the crane and lifted loads as shown in Figure 8 by clicking any of these objects. The Load Information Form is integrated with the lifted load database, schedule, wind forecast model, and reaction calculation model and is updated along with the database. The 3D visualization model can be shared with all involved in the project to identify specific instability accidents, spaceconflict, and errors of crane operation. The visualization improves construction key

8 1288 performance factors in terms of quality, on-time completion, cost, and safety. As scheduling is a major component of BIM models, the integration of the 3D visualization model with BIM is accomplished by linking the simulation outputs with the 3D model, allowing automatic changes in the project schedule depending on simulated/forecasted wind speeds. Figures 9-a and 9-b present the visualization of crane operations with wind speed, direction and support reactions for the crawler crane and tower crane, respectively. Instability accidents due to tipping of mobile cranes have generally resulted from faulty decisions to perform lifts which either exceed the lifting capacity of the crane or swing in an area that is not permitted by the crane load chart. The proposed BIM warns (in red) if the lifting operations are unsafe due to high wind speed (e.g. exceeds the allowable limit) or if any of the support reactions become negative (e.g. tipping failure may occur) as shown in Figure 9. (a) (b) Figure 8. Building Information Forms for (a) Crane, (b) Load (a) (b) Figure 9. BIM supported Visualization Models with Safety Warnings CASE STUDY The proposed methodology is tested in an industrial project in Saskatoon, Canada. The heaviest load, a mechanical system module, is 30 tons with attachments. Both mobile cranes and tower cranes are assessed to select the best possible crane considering the serviceability in storm wind conditions. The mobile crane used in this case study is a crawler crane (Liebherr LR 1300) and the tower crane is one of the largest luffing jib tower cranes (WT2405L) in Europe manufactured by Wilbert Crane, Germany. The support reactions are calculated according to the proposed methodology section using and stored in an MS Excel file. The wind data and support reactions are integrated with the developed model using BIM as shown in Figure 10 and 11 for crawler crane and tower crane operations, respectively.

9 1289 Figure 10. Crawler Crane Operations Model with Tracks Pressure and Wind Data Figure 11. Tower Crane Operations Model with Support Reactions and Wind Data From the simulation of historical wind data in Saskatoon it is found that wind speeds more than 15 m/s are probable a few times in a month. Figure 12 illustrates the pressure for both tracks for the crawler crane (Figure 12-a) and reactions for four legs for the tower crane (Figure 12-b) for 360 rotation at 20 m/s wind speed when the wind direction is from North to South and the lifted load is 30 tons. The allowable maximum wind speed for the selected mobile crane (13.9 m/s) suggests that the crane operations should be shut down about 5% of the total project duration (in days). As shown in Figure 12-a, the proposed methodology also suggests that there is a possibility of tipping failure of the crawler crane if it is still in operation when the wind speed is 20 m/s as track pressure becomes negative at 150 to 200 rotation condition (marked in the red circle). On the other hand, tower cranes maximum allowable wind speed is around 20 m/s. From this research it is found that the selected tower crane can operate safely at 20 m/s wind speed when the lifted load is 30 tons or less, as shown in Figure 12-b. Thus according to the proposed integrated model, the selected tower crane is a more feasible option than the crawler crane for this industrial project. However, the final selection of the crane depends on some other important factors such as cost, crane ownership and availability of technical support. (a) (b) Figure 12. Support Reactions at 20m/s Wind Speed

10 1290 CONCLUSION BIM adoption is increasing in North America, and many companies have started to realize the importance of changing their business process to be fully integrated with BIM. This paper presented a new approach to integrate weather information (currently only wind data) in BIM to control the crane operations. Integrating crane stability analysis using the wind data in BIM could open a new dimension to BIM thinking. Wind speed and direction and support reactions information in the visualization model will assist lift engineers to schedule crane operations more efficiently. The proposed methodology warns the user of cases of instability, which will assist in preventing crane accidents. One of the limitations of this research is that the methodology for calculating support reactions for the wind speed is approximate and static. To obtain more accurate results, dynamics analysis is required. Advanced research can be conducted using dynamics analysis software to identify the support reactions which can be added in BIM, as described by this paper. The significance of the proposed integrated BIM technology is that it focuses on improving workers safety. Planning for the crane operation using BIM for a largescale construction site and providing such information to all involved in the project will eliminate the guesswork and potential hazards. This research aims to establish lift planning standardization for large projects involving multiple heavy lifts. ACKNOWLEDGEMENTS The financial support of NSERC is gratefully acknowledged. The authors appreciated the assistance from Northern Crane Services, Edmonton, Canada and Wilbert Cranes, Germany. REFERENCES Beavers, J. E., Moore, J. R., Rinehart, R., and Schriver, W. R. (2006). Crane-Related Fatalities in the Construction Industry. Journal of Construction Engineering and Management, ASCE, 132(9), Construction Plane-hire Association (2009). The Effect of Wind on Mobile Crane in-service. < Eastman, C., Teicholz, P., Rafael, S., Liston, K. (2011). A Guide to Building Information Modeling for Owners, Managers, Designers, Engineers, and Contractors. Second Edition. John Wiley & Sons, Inc. Hajjar, D. and AbouRizk, S.M. (1999). Simphony: An Environment for Building Special Purpose Construction Simulation Tools. Proceedings of the 1999 Winter Simulation Conference, Phoenix, AZ, Hasan, S., Al-Hussein, M., Hermann, U.H., Safouhi, H. (2010). Interactive and Dynamic Module for Mobile Cranes Supporting System Design. Journal of Construction Engineering and Management, ASCE 136(2), Neeley, D, (2010). The Speed of Change. 2010SMARTBIM, Ross, B., McDonald, B., Saraf, S.E.V. (2007). Big Blue goes down. The Miller Park crane accident. Engineering Failure Analysis 14, Shapiro, H. I., Shapiro, Shapiro, J. P., and Shapiro, L. K. (1999). Cranes & Derricks. 3 rd Edition, McGraw-Hill, NewYork, N.Y.