Self-propelled Modular Transporters Research Articles

Traffic control of self-propelled modular conveyors

The paper deals with the issues of directional stability control of self-propelled modular transporters (SPMT). A thorough analysis of the operating modes and types of the SPMT drive was carried out, as a result of which a decision was made on the advisability of using electric traction drive systems. As a result of comparing the traction and operational characteristics of various types of electric drive, a DC electric drive was chosen, which, first of all, is due to the high starting torque and its adjustment capabilities. An analysis of the required ratio of SPMT wheel speeds for various types of movement made it possible to formulate general requirements for the traction drive control system in terms of ensuring directional stability. The latter made it possible to substantiate the expediency of using systems of subordinate regulation by a traction electric drive. Also in the work, the calculation of the control system of the traction electric drive is carried out and the results of a model experiment are presented.

Investigation of Cracks Observed on a Skewed Bridge Constructed Using Self-Propelled Modular Transporters

This study investigates full-depth deck cracks observed on a skewed bridge, which was constructed using self-propelled modular transporters (SPMTs). To investigate the causes, three main factors associated with structural design, material design, and construction are reviewed. Specifically, the bridge performance under thermal and construction loading is investigated by conducting a nonlinear finite-element analysis. The analysis parameters include bridge deck geometry, boundary conditions, bearing details, and skew angles. The loading conditions mainly include thermal and differential deck movements induced during an SPMT move. The results are compared to a crack map created from two site visits. It is concluded that skewed decks are more susceptible to cracking than straight decks due to an asymmetric expansion and contraction. Additionally, semi-integral abutment designs in a skewed bridge increase the extent of cracking in the skewed corners of the abutment ends. It is recommended that a semi-integral abutment design be carefully considered when designing a skewed bridge and that bearing and expansion joint details need careful attention for accelerated bridge construction.

Dynamic analysis of block offloading using self-propelled modular transporters

Abstract A self-propelled modular transporter (SPMT) is a platform vehicle with a large array of wheels that is used for transporting outsized objects. In a shipyard, a number of connected SPMTs are used to move outsized blocks transported from abroad to the floating dock to increase the productivity and reduce the operation time. This operation is called offloading. This study proposes a method of analyzing the offloading operation dynamically. To develop this method, multibody dynamics was used to analyze the motion of the transportation barge, and a floating dock connected by hinge joints was adopted. The modeling of the mechanical parts of the SPMT was also proposed, taking into consideration the axle compensation mechanism to maintain the level of the platform when the SPMT drives over an uneven roadway by lifting up the wheel. Furthermore, a non-interpenetration constraint method between a plane and the cylinder was derived for the collision between the wheels of the SPMT and the decks of the transportation barge and floating dock. The non-interpenetration constraint method was successfully applied to the dynamic analysis of block offloading using SPMTs. From the dynamic analysis, the safety criteria according to the given wave conditions were evaluated.

HEAVYLIFTING OPERATIONS FOR THE ASSEMBLY OF A 150 M LONG SIMPLY SUPPORTED BRIDGE DECK

The new viaduct over the Cadiz Bay includes a removable deck to allow the navigation of large floating structures, higher than the 69 m clearance of the main cable-stayed span of the bridge. For this purpose, a 150 m long simply supported span was designed, which can be assembled and disassembled. The steel deck, weighing 4,000 metric tons, was completely manufactured onshore, the challenge being to move such a massive structure to its final position above the piers. It required for several heavylifting maneuvers, such as land transportation and load-out with two 6 x 28 axle lines of self-propelled modular transporters (SPMTs), sailing with a 100 m long barge and positioning the deck in-between the piers with a tight gap, a lifting with eight strand jacks 850 T capacity each and a final transversal shifting. The aim of this paper being to describe all the activities and the heavylifting equipment employed for the assembly of such a massive deck.

Handling Heavier Loads in Construction

Heavy lifting and exceptional transport equipment has been developed in an amazing way in the last two decades. Some years ago, transporting and lifting elements with the weights and sizes that we are capable to transport and lift nowadays was inconceivable. Big cranes were used to lift few hundreds of tons but now projects go up to thousand tons and at very important working radius, alternative heavy lift systems such as gantries, jacks, etc. are used for special jobs and, regarding transportation, Self- Propelled Modular Transporters (SPMT) have been developing, increasing in number, and over 14.000 ton platforms have been moved on wheels. Shipping is also adapting fast to this scenario with higher capacity geared vessels and other type of multimodal ships.This capacity increase is being used in civil and industrial construction (occasionally even in building construction) by developing prefabrication and modularization since it opens the possibility to handle bigger and heavier pieces. The advantages for construction are very important: better safety because work can be achieved without working on heights, better quality because of working in a more controlled environment (prefabrication yards, factories, etc.), improving the schedules by working on several parts simultaneously, price reductions by optimizing construction methods, global sequence and locations.

Relocation of Industrial Facilities Using Self-Propelled Modular Transporters (SPMT`S)

Design of re-locatable industrial facilities is a new concept that evolved over the past few years due to the significant savings in project costs. Little guidelines are available in current codes of practice or in published literature to address the engineering challenges encountered in relocating industrial facilities. The paper sheds light on the requirements to design re- locatable structure. Industrial examples are also provided. A brief description is also given to illustrate the characteristics of the Self-Propelled Modular Transporter (SPMT) system. The engineering drawing requirements for the relocation procedure are also discussed. Design guidelines are proposed for practicing engineers in order to develop reliable relocation strategy. The paper also reviews engineering patents related to the subject. Keywords: Modular steel design, numerical models, Oil and gas facilities, petrochemical facilities, SPMT’s, steel design.

Induced Stresses from Lifting and Moving Highway Bridges with Self-Propelled Modular Transporters

This study discusses five bridges on I-80 in Utah that were replaced in the summer of 2008 by using accelerated bridge construction methods. Each superstructure was built off site and moved into place with self-propelled modular transporters. The bridges were instrumented and monitored during the moving process to investigate the effects of moving an entire superstructure into place. Collected data were analyzed to find the level of stress each superstructure experienced during lifting, moving, and placement of each bridge. Support conditions for these bridges changed considerably. During construction and when permanently placed, they were simply supported structures. During transport, the lift points were in the interior of the bridges, resulting in cantilevered ends and considerable stress reversals in the entire bridge. A two-dimensional analysis was done using the dead load of the structure to find the initial stresses in the superstructure when supported on temporary abutments. The measured change in stress resulting from lifting was compared with calculations. The difference between the two stresses was defined as the lifting stress in the superstructure. Dynamic stresses incurred as a result of bridge movement are determined and compared with recommendations.

Self Propelled Trailers Used to Advantage in Florida Bridge Project

This article describes the use of a computer-controlled, multiaxial trailer to lift heavy prefabricated structural components into position on a Florida bridge-building project. By using the trailer, the Florida Department of Transportation (FDOT) reduced the number of days an interstate highway needed to be closed from 32 to four. In addition, this project was the first in the U.S. to use this technology on an interstate overpass. The article describes the Graves Avenue bridge project in central Florida, the bridge that needed replacement, the costs of the project, and the use of the self-propelled modular transporters (SPMTS). The new technology allowed the old bridge spans to be removed in two 20-minute periods on two nights. Had the bridge been demolished using cranes, the project would have taken 12 nights of lane closures and 20 nights to construct the new bridge.

Prefabricated Bridge Elements and Systems in Japan and Europe

In April 2004, a scanning tour of Japan, the Netherlands, Belgium, Germany, and France was made to obtain information about bridge construction methods being used to minimize traffic disruption, improve work zone safety, minimize environmental impact, improve constructibility, increase quality, and lower life-cycle costs. From information obtained from the tour, 10 technologies were identified for further consideration and possible implementation into U.S. practices. These included two technologies that allow bridges to be built off site and then moved to their final location in a short time, three superstructure systems and four deck systems that facilitate faster and safer construction, and one substructure system. The two technologies for moving bridges were self-propelled modular transporters and other moving systems, including skidding or sliding, incremental launching, floating, rotating, and lifting of bridges into place. The superstructure systems included a precast concrete deck system known as the Poutre Dalle system, the use of partial-depth concrete decks prefabricated on steel or concrete beams, and U-shaped precast concrete segments with transverse ribs. The deck systems involved full-depth prefabricated concrete decks, special cast-in-place closure joint details, hybrid steel–concrete deck systems, and a multiple-level corrosion protection system. The substructure system consisted of stay-in-place precast concrete panels that serve as both formwork and structural elements for solid and hollow bridge piers.

Self-Propelled Modular Transporters for Bridge Movements in Europe and the United States

More than 150,000 publicly owned vehicular bridges in the United States are currently structurally deficient or functionally obsolete. The rate at which additional bridges become deficient or obsolete is anticipated to increase as traffic volumes and weights continue to increase and as more bridges across the country reach the end of their service life. New methods are needed to replace these substandard bridges quickly with long-lasting bridges while traffic flow is maintained. Bridge prefabrication is one method that can address this need. An international scan was conducted in April 2004 to learn how other countries are using prefabricated bridge components to minimize traffic disruption, improve work-zone safety, minimize environmental impact, improve constructability, improve quality, and lower life-cycle costs. Countries visited were Japan, the Netherlands, Belgium, Germany, and France. The top implementation recommendation from the scan team is the use of self-propelled modular transporters to move bridges into position in hours rather than the typical months required for conventional bridge construction.

Part 3: Concrete Bridges: Prefabricated Bridge Elements and Systems in Japan and Europe

In April 2004, a scanning tour of Japan, the Netherlands, Belgium, Germany, and France was made to obtain information about bridge construction methods being used to minimize traffic disruption, improve work zone safety, minimize environmental impact, improve constructibility, increase quality, and lower life-cycle costs. From information obtained from the tour, 10 technologies were identified for further consideration and possible implementation into U.S. practices. These included two technologies that allow bridges to be built off site and then moved to their final location in a short time, three superstructure systems and four deck systems that facilitate faster and safer construction, and one substructure system. The two technologies for moving bridges were self-propelled modular transporters and other moving systems, including skidding or sliding, incremental launching, floating, rotating, and lifting of bridges into place. The superstructure systems included a precast concrete deck system known as t...