ADJUSTABLE CROSS-FRAME ASSEMBLY AND METHOD OF USE THEREOF
An adjustable cross-frame assembly includes a first elongate flexible line, a second elongate flexible line, and an adjustable-length jack assembly. The first elongate flexible line is coupled in tension to a first portion of a first girder and to a second portion of a second girder. The first elongate flexible line extends concurrently with a plane that intersects both of the first and second girders. The second elongate flexible line is coupled in tension to a second portion of the first girder and to a second portion of the second girder. The second elongate flexible line extends concurrently with the plane. The adjustable-length jack assembly is coupled to the first portion of the first girder and to the second portion of the second girder. The adjustable-length jack assembly extends concurrently with the plane.
This application claims priority to U.S. Provisional Application No. 63/367,065, filed, Jun. 27, 2022, the entire content of which is hereby incorporated by reference.
GOVERNMENT LICENSE RIGHTSThis invention was made with government support under the Innovation Deserving Exploratory Analysis (IDEA) Program awarded by the Transportation Research Board of the National Academies of Sciences, Engineering, and Medicine. The government has certain rights in the invention.
FIELDEmbodiments described herein relate to the installation of cross-frames between girders of a structure, such as a bridge or overpass.
SUMMARYIn one aspect, embodiments disclosed herein relate to an adjustable cross-frame assembly includes a first elongate flexible line, a second elongate flexible line, and an adjustable-length jack assembly. The first elongate flexible line is coupled in tension to a first portion of a first girder and to a first portion of a second girder. The first elongate flexible line extends in a direction approximately parallel with a plane that intersects both of the first and second girders. The second elongate flexible line is coupled in tension to a second portion of the first girder and to a second portion of the second girder. The second elongate flexible line extends in a direction approximately parallel with the plane. The adjustable-length jack assembly is coupled to the first portion of the first girder and to the second portion of the second girder. The adjustable-length jack assembly extends in a direction approximately parallel with the plane.
In another aspect, embodiments disclosed herein relate to an adjustable cross-frame assembly to facilitate the installation of cross-frames between girders. The adjustable cross-frame assembly includes a first elongate rigid beam, a second elongate rigid beam, and an adjustable-length jack assembly. The first elongate rigid beam is coupled to a first portion of a first girder and to a first portion of a second girder. The first elongate rigid beam extends in a direction approximately parallel with a plane intersecting both of the first and second girders. The second elongate rigid beam is coupled to a second portion of the first girder and to a second portion of the second girder. The second elongate rigid beam extends in a direction approximately parallel with the plane. The adjustable-length jack assembly is coupled to the first portion of the first girder and to the second portion of the second girder. The adjustable-length jack assembly extends in a direction approximately parallel with the plane.
In another aspect, embodiments disclosed herein relate to a method of installing cross-frames between girders. The method includes coupling a first elongate member of a fixed length to a first portion of a first girder and to a first portion of a second girder. The first elongate member extends in a direction approximately parallel with a first plane intersecting both of the first and second girders. The method further includes coupling a second elongate member of a fixed length to a second portion of the first girder and to a second portion of the second girder. The second elongate member also extends in a direction approximately parallel with the first plane. The method also includes coupling an adjustable-length jack assembly to the first portion of the first girder and to the second portion of the second girder. The adjustable-length jack assembly also extends in a direction approximately parallel with the plane. The adjustable-length jack assembly includes a variable-length strut (e.g., a pipe strut) and a jack (e.g., a double-acting hydraulic jack). The method further includes adjusting a length of the adjustable-length jack assembly by actuating the jack, thereby rotating at least one of the first and second girders to make the first and second girders locally approximately parallel with each other. The method also includes installing a cross-frame coupling the first and second girders together. The method further includes removing the first elongate member, the second elongate member, and the adjustable-length jack assembly from the first and second girders.
One or more embodiments are described and illustrated in the following description and accompanying drawings. These embodiments are not limited to the specific details provided herein and may be modified in various ways. Furthermore, other embodiments may exist that are not described herein.
In addition, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. For example, the use of “including,” “containing,” “comprising,” “having,” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The terms “connected” and “coupled” are used broadly and encompass both direct and indirect connecting and coupling. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings and can include electrical connections or couplings, whether direct or indirect. In addition, electronic communications and notifications may be performed using wired connections, wireless connections, or a combination thereof and may be transmitted directly or through one or more intermediary devices over various types of networks, communication channels, and connections. Moreover, relational terms such as first and second, top and bottom, and the like may be used herein solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.
The design, fabrication, and installation of cross-frames for curved and highly skewed steel girder bridges can be difficult and time-consuming. In these bridges, the girders twist and deflect such that there is only one fit condition for which girders are plumb and cross-frames could be installed without force-fitting. This interaction between interim girder geometry and cross-frame fit can result in the following challenges: (1) un-planned force-fitting and hole reaming may be required in the field, (2) girder webs do not meet plumbness requirements, potentially resulting in high locked-in stresses, both in the cross-frames and girders, (3) excessive bearing rotations, and (4) poor joint alignment.
Three fit conditions that are typically used in practice, with the assumption that the girder webs are plumb and the cross-frames are minimally loaded in only one of these configurations, are: (1) No Load Fit (NLF), (2) Steel Dead Load Fit (SDLF), or (3) Total Dead Load Fit (TDLF). Since the designer or owner chooses one condition for the fabricator/erector, this implies that both girders and cross-frames are designed for the interim conditions and that any locked-in forces in the final composite condition do not compromise the overall load-carrying ability of the system.
In a skewed girder bridge, each consecutive girder with identical span length stiffness and cross-section has a different deflection along a line perpendicular to the structure. If the cross-frames are detailed for TDLF but are installed under only the deflection of the steel dead load, the installer will be required to apply additional external forces to the girder and cross-frame system to force-fit the connections, causing some temporary torsional and vertical distortion in each of the girders. In a curved girder system, the effects are exaggerated since the girder center of gravity falls outside the line of action between the supports. Steel girders in this system, whether skewed or normal, have both vertical bending and torsion that amplifies the relative displacements between girders and dramatically complicates fit-up.
The more curved and skewed a bridge is, there is a strong tendency toward SDLF, given that this enhances constructability in the field. However even this can present challenges, as there are often circumstances where curved girders are picked in pairs with cross-frames already installed (i.e., in the NLF condition) or the use of intermediate props or hold cranes introduces another unforeseen set of assumptions. Any changes impact cross-frame forces, camber, and therefore final girder forces, leaving the potential for new bridges to have overstressed components.
As an example, for SDLF or TDLF, the detailer would typically determine the girder geometry by taking the fully-cambered no load girder geometry and subtract the deflections under the steel dead load or total dead load, respectively. The fully-cambered no load girder geometry would have been determined based on the profile of the road and the total dead load deflections. This calculation would determine the “drop” as shown in
In current practice, the designer typically assumes an erection strategy, requiring that the fabricator use the same assumptions and to lock into a specific geometry. Just as importantly, shop fabrication tolerances and restrictions associated with progressive laydown of curved and skewed girder bridges can influence fit-up. The erector then has the challenge of building the bridge as fabricated which likely differs from his/her means and methods. This makes erection more complicated and requires some degree of force-fitting. Force-fitting induces forces that the designer did not anticipate, potentially invalidating the design. This can lead to restrictions on erection, which adds cost and complexity to the project and often involves re-evaluation by the designer. The fabricator spends a lot of time with precision fabrication, and all of this effort at achieving geometry ends up making erection more difficult instead of easier.
Current practice for cross-frame installation when alignment is not achieved involves conventional steel erection equipment such as drift pins, “come-along” tools, chain winches, timber blocking, and crane load manipulation. Such methods are not precise and often involve no definite plan other than installing all required bolts. For example, if the top of the two girder field segments being erected are 2.67 m (8 feet and 9 inches) apart and should be 2.59 m (8 feet and 6 inches) apart, come-along tools might be attached to the opposing top flanges and used to pull the tops together. Likewise, timber blocking might be used between bottom flanges to maintain a particular spacing. In order to install the bolts in the prefabricated cross-frame, drift pins, additional hand-pulling, and crane load manipulation may all need to be employed. These techniques are performed in an ad-hoc manner and may induce unknown stresses in the cross-frames and/or girders, as well as pose safety hazards to the workers conducting the tasks.
It would be desirable to provide a cost-effective, deployable tool for the construction of highly skewed and curved steel girder bridges. Such a device and method could provide the necessary geometry adjustments to the adjacent girders for the fit-up and installation of cross-frames.
To address these challenges in installing cross-frames, an adjustable cross-frame assembly 100 can provide geometry adjustments in adjacent girders G1, G2 for fit-up and installation of cross-frames CF without force-fitting.
Turning now to
As shown in
The permanent cross-frame CF is then installed and the adjustable cross-frame assembly 100 is then removed. The adjustable cross-frame assembly 100 is then available to be used once more at another location along the girders G1, G2 and/or for other girder lines along the same structure or on other structures.
The geometry adjustment may be considered adequate (e.g., minimal to no force-fitting is required for the installation of a permanent, rigid cross-frame CF) if the diagonal lengths L1 and L2 match their respective target (ideal) lengths (L1T and L2T) within a threshold of, for instance, 3.18 mm (⅛ inches) [such that |δL|<3.18 mm (⅛ inches), where δL=Lγ−L, for L1 and L2].
The adjustable cross-frame assembly 100 increases flexibility in fabrication and erection while reducing the potential for overstress in the system. The use of the adjustable cross-frame assembly 100 may enable fabrication using one set of fit assumptions and field adjustments to accommodate another set of assumptions, whether that be from different erection assumptions, fabrication tolerances, camber variations, or other unanticipated geometry variations.
To demonstrate the adjustable cross-frame assembly 100 in a realistic construction scenario, the behaviors of a highly skewed steel girder bridge and a curved steel girder bridge that have recently been constructed have been investigated.
As shown in
As shown in
As shown in
Both girders G1, G2 are supported at one pier and segments extend past the field splice and onto temporary falsework (not shown). At the pier, the top of the cross-section of the first girder G1 is laterally braced with a temporary support. The first girder G1 is also supported by crane C3, and the second girder G2 is supported by cranes C1, C2. Based on the erection engineering documentation, the crane forces at this increment are: crane C1—142 kN (32 kips); crane C2—4.45 kN (1 kip); and crane C3—142 kN (32 kips). No cross-frames have been installed at this construction increment. The distance D1 between the pier and crane C1 is 10.7 m (31 ft). The distance D2 between crane C1 and crane C2 is 42.1 m (138 ft). The distance D3 between the pier and crane C3 is 22.9 m (75 ft). The distance D4 between crane C3 and the end of the first girder G1 is 24.4 m (80 ft).
Three-dimensional finite element (FE) analyses of the prototype bridges were performed to understand the differential vertical deflection and/or rotation at the construction increment before cross-frame CF installation. The efficacy of the adjustable cross-frame assembly 100 is then demonstrated for the highly skewed bridge.
For both types of analyses, the FE models were built in the software package ABAQUS (2022), using S4R or S3R general-purpose shell elements. Static analyses of the increment of construction when cross-frames CF would be installed were performed under the steel dead load. Nonlinear geometry was assumed. A linear material model for the steel girders and cross-frames was assumed, with a Young's modulus of 200 GPa (29,000 ksi) and density of 7,850 kg/m3 (0.490 kcf). A mesh size of 152 mm (6 inches) was used based on the results from mesh refinement studies.
For the highly skewed bridge shown in
For the curved bridge shown in
For both bridges, no transverse slope was modeled (i.e., both girder lines were assumed to be at the same vertical position), for simplicity. For the highly skewed bridge shown in
No cross-frames were modeled when investigating the behavior under steel dead load.
When investigating behavior using the adjustable cross-frame assembly 100, a staged FE model was developed to understand behavior at each step of the deployment sequence of the adjustable cross-frame assembly 100. In the first stage of the FE model, both girders G1, G2, all cross-frames, and the adjustable cross-frame (at each location where it will be used) are in the assembly. Then the boundary conditions are applied and all cross-frames are de-activated (such that not even the effect of their dead load is incorporated in the model). The dead load is applied to all active components. This corresponds to Step 1 of the sequence to be discussed later. Then, in individual stages and according to the desired sequence, the adjustable cross-frame assembly 100 is utilized or cross-frames CF are activated.
For modeling of the adjustable cross-frame assembly 100, the elongate flexible lines 102 were modeled as tension-only truss elements with a Young's modulus of 103 GPa (15,000 ksi) and a cross-sectional area of 269 mm2 (0.417 in2). The adjustable-length jack assembly 106 was modeled as a truss element with a Young's modulus of 200 GPa (29,000 ksi) and a cross-sectional area of 2,030 mm2 (3.14 in2), allowing both tension and compression. “Coupling” constraints were used to represent “pin” connections (i.e., translation is coupled in all directions, but rotation is not), joining the adjustable cross-frame assembly 100 to the girders G1, G2. At a stage when the adjustable cross-frame assembly 100 is not in use, the Young's modulus is reduced to a negligibly small value such that it has an insignificant impact on behavior. At a stage when the adjustable cross-frame assembly 100 is in use, the Young's modulus is increased to the desired 103 GPa (15,000 ksi) value and a thermal load is applied to the truss element that represents the adjustable-length jack assembly 106, thereby simulating the elongation and/or contraction of the jack. The magnitude of the thermal load (which relates to the magnitude of the increase or decrease in length of the adjustable-length jack assembly 106) was determined based on the difference between the current length of the diagonals, L1 and L2 at the cross-frame location at the prior step as compared to the target length of the diagonals L1T, L2T at the cross-frame location.
At a stage where a cross-frame CF would be installed, that part is then activated. The cross-frames CF are modeled as shell elements with the form and section sizes as shown in
D=(yDL−G1−yDL−G2)−d
where yDL−G1 is the vertical coordinate of girder G1 under steel dead load only when it is supported per the construction increment shown in
The peak differential vertical deflection occurs at cross-frame location 3 with a magnitude of 11.4 mm (0.448 in). In comparison, the differential vertical deflections at location 8 and 9 are less than 3.18 mm (0.125 in.), such that these two cross-frames could be installed with limited to no force fitting. Along the entire girder length, there is negligible rotation, as expected for a straight, skewed bridge.
These differential vertical deflections and rotations are unique to the prototype bridges investigated here, the fit conditions assumed in this investigation, and the modeling assumptions made in this investigation
Given the differential vertical deflections/and or girder rotations found for the prototype bridges, a control sequence of when and where the deployable tool should be used, including the installation of the cross-frames, was developed. The forces in the deployable tool during adjustment and the stresses in the installed cross-frames were evaluated during this process.
In this investigation, the philosophy for determining the sequence was developed with the aim of (1) simplifying the necessary analyses to be performed by the engineer to use adjustable cross-frame assembly 100 and (2) minimizing the number of times the adjustable cross-frame assembly 100 would need to be used to install the cross-frames as rapidly as possible.
A philosophy for determining the sequence, which is used in this investigation, is as follows. An engineer performs an analysis of the construction stage when cross-frames would be installed to determine the differential vertical deflections/rotations under steel dead load (with no cross-frames included in the analysis). With the assumption that cross-frames could be installed with minimal or no force-fitting if the differential vertical deflection, D is less than 3.18 mm (0.125 in.) and/or |δL|<3.18 mm (⅛ in) for both diagonals L1, L2, it would be recommended that any cross-frame locations for which the differential vertical deflection, D is less than 3.18 mm (0.125 in.) and/or |δL|<3.18 mm (⅛ in) for both diagonals L1, L2 be installed first. Then the adjustable cross-frame assembly 100 would be deployed near the cross-frame location with the highest differential vertical deflections/rotations. The jack assembly 106 would either extend or contract, as necessary such that |δL|<3.18 mm (⅛ in) for both diagonals L1, L2. That cross-frame would then be installed. The adjustable cross-frame assembly 100 would then be removed and reused elsewhere. Note that while the adjustable cross-frame assembly 100 is deployed, the contractor could inspect for any other cross-frames that could be installed without force fitting and install those as well. This could be done while the adjustable cross-frame assembly 100 is deployed or after it is removed.
The contractor would then determine where the adjustable cross-frame assembly 100 should be deployed next based on observing which cross-frame would be the next most difficult to install. This could also be determined based on the largest difference SL between the diagonal lengths L1, L2 and the target lengths L1T, L2T at each cross-frame location. This would be repeated as needed until all cross-frames are installed. As un-anticipated geometry variations may occur, the contractor could alter this sequence as needed. The engineer could specify a maximum allowable force that could be used in the adjustable-length jack assembly 106 and allow the contractor to use any amount of force necessary up to this maximum allowable force at each time the contractor uses the adjustable cross-frame assembly 100.
If the differential vertical deflections are greater than 3.18 mm (0.125 in.) and/or |δL|>3.18 mm (⅛ in) for either diagonal L1 or L2 at the cross-frame nearest to a support or boundary condition, then the adjustable cross-frame assembly 100 could be used to facilitate the installation of that cross-frame first (even if it isn't the one with the highest differential vertical deflections and/or rotations). This is to overcome the challenge of installing cross-frames near support or boundary conditions which resist relative geometry changes of the girders. After this, then the cross-frames with the highest differential vertical deflections/rotations should be installed.
Throughout this procedure the threshold of |δL|<3.18 mm (⅛ in) for both diagonals L1, L2 has been used to indicate that a cross-frame can be installed with no or minimal force fitting. Other thresholds could be specified.
Alternatively, one can envision that the contractor can use the adjustable cross-frame assembly 100 where it is needed based on the contractor's observations or experience. An engineer could prescribe a maximum allowable force that could be used in the adjustable-length jack assembly 106 and allow the contractor to use any amount of force necessary up to this maximum allowable force. This approach would permit more flexibility for overcoming different erection assumptions, fabrication tolerances, camber variations, or other unanticipated geometry variations. Other sequences could also be envisioned, for example based on site conditions and which locations may be the easiest for the adjustable cross-frame assembly 100 to be deployed.
In this investigation, the adjustable cross-frame assembly 100 is installed 6 in. away from the cross-frame location with the highest magnitude of differential vertical deflections/rotations. Alternatively, it could be placed midway between two cross-frame locations with the highest magnitudes of differential vertical deflections/rotations, with the aim of facilitating the installation of two cross-frames at once.
At each time the adjustable cross-frame assembly is installed, the user should evaluate if the jack assembly 106 should be extended or contracted, based on the current diagonal lengths L1, L2 as compared to the target diagonal lengths L1T, L2T. If δL>0, then that diagonal should be lengthened. If δL<0, then that diagonal should be shortened. The users should also determine which orientation the jack assembly 106 should be used in, for example parallel to L1 or parallel to L2.
Table 1 above shows the control sequence for deploying the adjustable cross-frame assembly 100 and installing the cross-frames CF for the highly skewed bridge (
Only one adjustable cross-frame assembly 100 is used in the sequence, but it is moved to different locations at different points in the sequence. Alternatively, a contractor could use more than one adjustable cross-frame assembly 100 to achieve the installation of the cross-frames.
Recalling the differential vertical deflections shown in
As cross-frame location 1 has differential vertical deflections exceeding 3.18 mm (0.125 in.) and it is near the support, the adjustable cross-frame assembly 100 is used to first install this cross-frame CF1, even though the largest different vertical deflection occurs at CF 3. The adjustable cross-frame assembly 100 is installed 152 mm (6 in) away from cross-frame location 1, which is where the next cross-frame CF1 would be installed, in the longitudinal direction. The adjustable-length jack assembly 106 is extended until |δL|<3.18 mm (⅛ in) for both diagonals L1, L2, with forces in the adjustable cross-frame assembly 100 shown in Table 1 above. Note that throughout the present disclosure, positive indicates tension, and negative indicates compression. A cross-frame CF1 is then installed at cross-frame location 1, and the adjustable cross-frame assembly 100 is released. This release results in stresses being imparted into the cross-frame CF1 (with reference to
After installing cross-frame CF1, it was observed numerically (and could be observed physically by the contractor), that cross-frame CF7 meets the |δL|<3.18 mm (⅛ in) for both diagonals L1, L2. Cross-frame CF7 is then installed. Note that cross-frame CF7 actually met this criterion at Step 1 and could have been installed in Step 2. However, this was not done in this document because the initial decisions on which cross-frame to install at Step 2 were made based solely on the differential vertical deflection, D. Then, the adjustable cross-frame assembly 100 would be used to install the cross-frame that has the highest differential vertical deflection/rotation. In this case, that would be cross-frame CF3 at the cross-frame location 1. The adjustable cross-frame assembly 100 would again be installed 152 mm (6 in) away longitudinally from the cross-frame location 3. In this case, the jack assembly 106 is retracted (as opposed to extended) based on the current lengths L1, L2 as compared to the target lengths L1T, L2T. Then, cross-frame CF3 would be installed, using a similar procedure, at the cross-frame location 3.
It was then observed numerically (and could be observed physically by the contractor), that cross-frames CF2, CF 4 now meet the |δL|<3.18 mm (⅛ in) for both diagonals L1, L2. Cross-frames CF2, CF4 were then installed. And the procedure could continue until all cross-frames were installed.
In some embodiments, throughout the sequence, the force in the adjustable-length jack assembly 106 never exceeded 16.0 kN (3.61 k) (see Table 1 above), which could be readily achieved with off-the-shelf technologies. Further, the stresses in the permanent cross-frames CF remain low [peak von Mises stress is 22.4 MPa (3.25 ksi); see Table 2 and Table 3 above], indicating that the procedure is not over-stressing components. Additionally, the crane forces remained almost constant throughout, indicating that the process was not inducing additional forces on the cranes C. The peak change in force in a crane C was 6.87% [i.e., 237 kN (53.4 k) in Crane 2 in Step 1 compared to 254 kN (57.1 k) in Step 10].
This strategy focused on differential vertical deflections for determining the sequence as it was for a highly skewed bridge where no significant rotations result. If there are significant rotations, these could also be considered in determining the sequence (e.g., in the case of the curved girder bridge).
This investigation used one approach for determining the sequence for the use of the adjustable cross-frame assembly 100 and installation of the cross-frames. Other approaches could be developed.
The embodiment in
Also shown in
The embodiment of the adjustable cross-frame assembly 200 shown in
Also shown in
In some embodiments, the elongate flexible lines 102, 104 are configured to pull while the adjustable-length jack assembly 106 is configured to push. In other embodiments, the elongate rigid beams 202, 204 are configured to push while the adjustable-length jack assembly 106 is configured to pull. In some embodiments, both an elongate flexible line and an elongate rigid beam may be used together, such that the elongate flexible line is configured to pull and the elongate rigid beam is configured to push. In some embodiments, the elongate rigid beams are also capable of pulling.
Other embodiments contemplated herein could include a plurality of adjustable-length jack assemblies 106 in various orientations and locations to accomplish the same or similar tasks.
While the focus of this disclosure has been on the use of the adjustable cross-frame assembly to facilitate cross-frame installation for highly skewed and curved girder bridges, the adjustable cross-frame assembly 100 also has the potential to aid in the addition of girder lines to widen a bridge. A potential additional application includes stabilizing girders during deck replacement. While I-beams have been illustrated and described, the present disclosure contemplates any form of beam. While steel beams have been illustrated and described, the present disclosure contemplates beams of any material (e.g., prestressed concrete).
Various features and advantages of some embodiments are set forth in the following claims.
Claims
1. An adjustable cross-frame assembly for installing cross-frames between girders, the adjustable cross-frame assembly comprising:
- a first elongate flexible line coupled in tension to a first portion of a first girder and to a first portion of a second girder, the first elongate flexible line extending in a direction approximately parallel with a plane intersecting the first and second girders;
- a second elongate flexible line coupled in tension to a second portion of the first girder and to a second portion of the second girder, the second elongate flexible line extending in a direction approximately parallel with the plane; and
- an adjustable-length jack assembly coupled to the first portion of the first girder and to the second portion of the second girder, the adjustable-length jack assembly extending in a direction approximately parallel with the plane.
2. The adjustable cross-frame assembly of claim 1, further comprising a first chain fall including the first elongate flexible line and a second chain fall including the second elongate flexible line.
3. The adjustable cross-frame assembly of claim 2, wherein the adjustable-length jack assembly includes a hydraulic jack.
4. The adjustable cross-frame assembly of claim 3, wherein the hydraulic jack includes a double-acting hydraulic cylinder.
5. The adjustable cross-frame assembly of claim 4, wherein the adjustable-length jack assembly includes a variable-length pipe strut.
6. The adjustable cross-frame assembly of claim 1, wherein each of the first elongate flexible line and the second elongate flexible line includes a cable.
7. The adjustable cross-frame assembly of claim 1, wherein each of the first elongate flexible line, the second elongate flexible line, and the adjustable-length jack assembly is bolted to both of the first and second girders.
8. The adjustable cross-frame assembly of claim 7, wherein
- each of the first and second girders includes plates coupled thereto, and
- each of the first elongate flexible line, the second elongate flexible line, and the adjustable-length jack assembly is coupled to one or more of the plates.
9. The adjustable cross-frame assembly of claim 1, further comprising a plurality of clamp brackets configured to removably couple each of the first elongate flexible line, the second elongate flexible line, and the adjustable-length jack assembly to the first and second girders.
10. An adjustable cross-frame assembly for installing cross-frames between girders, the adjustable cross-frame assembly comprising:
- a first elongate rigid beam coupled to a first portion of a first girder and to a first portion of a second girder, the first elongate rigid beam extending in a direction approximately parallel with a plane intersecting the first and second girders;
- a second elongate rigid beam coupled to a second portion of the first girder and to a second portion of the second girder, the second elongate rigid beam extending in a direction approximately parallel with the plane; and
- an adjustable-length jack assembly coupled to the first portion of the first girder and to the second portion of the second girder, the adjustable-length jack assembly extending in a direction approximately parallel with the plane.
11. The adjustable cross-frame assembly of claim 10, wherein each of the first elongate rigid beam and the second elongate rigid beam includes a threaded rod.
12. The adjustable cross-frame assembly of claim 11, wherein the adjustable-length jack assembly includes a hydraulic jack.
13. The adjustable cross-frame assembly of claim 12, wherein the hydraulic jack includes a double-acting hydraulic cylinder.
14. The adjustable cross-frame assembly of claim 13, wherein the adjustable-length jack assembly includes a variable-length pipe strut.
15. The adjustable cross-frame assembly of claim 10, further comprising a plurality of clamp brackets configured to removably couple each of the first elongate rigid beam, the second elongate rigid beam, and the adjustable-length jack assembly to the first and second girders.
16. The adjustable cross-frame assembly of claim 10, wherein
- each of the first and second girders includes plates coupled thereto, and
- each of the first elongate rigid beam, the second elongate rigid beam, and the adjustable-length jack assembly is coupled to one or more of the plates.
17. The adjustable cross-frame assembly of claim 10, wherein the first portion of the first girder includes an upper third of the first girder, the first portion of the second girder includes an upper third of the second girder, the second portion of the first girder includes the lower third of the first girder, and the second portion of the second girder includes the lower third of the second girder.
18. A method of installing cross-frames between girders, the method comprising:
- coupling a first elongate member of a fixed length to a first portion of a first girder and to a first portion of a second girder, such that the first elongate member extends in a direction approximately parallel with a first plane intersecting both of the first and second girders;
- coupling a second elongate member of a fixed length to a second portion of the first girder and to a second portion of the second girder, such that the second elongate member extends in a direction approximately parallel with the first plane;
- coupling an adjustable-length jack assembly to the first portion of the first girder and to the second portion of the second girder, such that the adjustable-length jack assembly extends in a direction approximately parallel with the first plane, the adjustable-length jack assembly including a variable-length strut and a jack;
- adjusting a length of the adjustable-length jack assembly by actuating the jack, thereby rotating at least one of the first and second girders to make the first and second girders locally approximately parallel with each other;
- installing a cross-frame coupling the first and second girders together; and
- removing the first elongate member, the second elongate member, and the adjustable-length jack assembly from the first and second girders.
19. The method of claim 18, further comprising
- coupling the first elongate member to a first portion of the first girder and to a first portion of the second girder, such that the first elongate member extends in a direction approximately parallel with a second plane intersecting both of the first and second girders at another position along a length of the first and second girders;
- coupling the second elongate member to a second portion of the first girder and to a second portion of the second girder, such that the second elongate member extends in a direction approximately parallel with the second plane;
- coupling the adjustable-length jack assembly to the first portion of the first girder and to the second portion of the second girder, such that the adjustable-length jack assembly extends in a direction approximately parallel with the second plane;
- adjusting a length of the adjustable-length jack assembly by actuating the double-acting hydraulic jack;
- installing another cross-frame coupling the first and second girders together; and
- removing the first elongate member, the second elongate member, and the adjustable-length jack assembly from the first and second girders.
20. The method of claim 18, wherein
- the first plane intersects both of the first and second girders at a location where at least one of a differential vertical deflection and a differential rotation of the first and second girders is greatest under a steel dead load with the first and second girders supported in a manner substantially identical to a cross-frame installation condition.
21. The method of claim 18, wherein
- the cross-frame is designated as a first cross-frame,
- the first cross-frame is installed on a first side of the first plane, and
- a second cross-frame is installed on a second side of the first plane opposite the first side.
22. The method of claim 18, wherein
- the first plane intersects both of the first and second girders at a location, and
- the first cross-frame is installed between the first plane and a boundary condition.
Type: Application
Filed: Jun 14, 2023
Publication Date: Dec 28, 2023
Inventors: Ashley P. Thrall (South Bend, IN), Shiyao Sun (South Bend, IN), Camila Duarte (South Bend, IN), David D. Byers (South Bend, IN), Theodore P. Zoli (South Bend, IN)
Application Number: 18/335,090