U.S. patent application number 13/751918 was filed with the patent office on 2013-06-06 for method for building over an opening via incremental launching.
This patent application is currently assigned to HNTB HOLDINGS LTD.. The applicant listed for this patent is HNTB HOLDINGS LTD.. Invention is credited to THEODORE PETER ZOLI.
Application Number | 20130139330 13/751918 |
Document ID | / |
Family ID | 40532789 |
Filed Date | 2013-06-06 |
United States Patent
Application |
20130139330 |
Kind Code |
A1 |
ZOLI; THEODORE PETER |
June 6, 2013 |
METHOD FOR BUILDING OVER AN OPENING VIA INCREMENTAL LAUNCHING
Abstract
Methods and systems for building a stress ribbon structure over
an opening via incremental launching, a construction fixture, a
support structure, an anchorage panel, and a stress ribbon
structure are disclosed. Construction fixtures are constructed
adjacent to a support structure. The stress ribbon structure is
constructed in a staging area and in sections that are suspended
between the construction fixtures. Anchorage panels at each end of
a section engage a blister on the construction fixtures and the
support structure. Completed sections are launched from the
construction fixtures onto and along the support structure.
Sections are individually constructed and launched and adjacent
sections abut along a lateral edge. Adjacent sections are aligned
by adjusting tension in integral support cables and their ends
pivot or rotate about the blisters via a bearing system with both
rotational flexibility and low friction to support sliding in the
direction of launching.
Inventors: |
ZOLI; THEODORE PETER;
(JERSEY CITY, NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HNTB HOLDINGS LTD.; |
Kansas City |
MO |
US |
|
|
Assignee: |
HNTB HOLDINGS LTD.
Kansas City
MO
|
Family ID: |
40532789 |
Appl. No.: |
13/751918 |
Filed: |
January 28, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12907552 |
Oct 19, 2010 |
8359810 |
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13751918 |
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12248599 |
Oct 9, 2008 |
7814724 |
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12907552 |
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60978622 |
Oct 9, 2007 |
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Current U.S.
Class: |
14/73 ;
14/78 |
Current CPC
Class: |
E04B 7/14 20130101; E01D
19/12 20130101; E01D 21/065 20130101; E01D 11/00 20130101 |
Class at
Publication: |
14/73 ;
14/78 |
International
Class: |
E01D 21/06 20060101
E01D021/06; E01D 19/12 20060101 E01D019/12 |
Claims
1. A construction fixture for constructing a stress ribbon
structure via incremental launching comprising: a foundation system
configured to support loads associated with a static stress ribbon
section and forces that result from launching the stress ribbon
section; a blister that is located on a top surface of the
construction fixture and that is configured to engage a bearing
surface of an anchorage panel of the stress ribbon section, wherein
the blister extends across the top surface of the construction
fixture parallel to a direction of launching; and one or more
bearings installed on a surface of the blister aid sliding of the
anchorage panel along the blister during launching, wherein the
construction fixture is constructed adjacent to a support structure
at a first side of an opening and opposite a second construction
fixture constructed at a second side of the opening, the
construction fixture supports a first end of the stress ribbon
section during construction of the stress ribbon section, and the
stress ribbon section is launched by one or more of pushing or
pulling the stress ribbon section to slide the anchorage panel
thereof along the blister, wherein launching the stress ribbon
section slides the anchorage panel from the construction fixture
onto the support structure, and wherein the construction fixture is
removed from its position adjacent to the support structure after
the stress ribbon section is launched onto the support structure
thereby leaving the support structure to independently support the
stress ribbon section.
2. A support structure for receiving and supporting a stress ribbon
structure constructed via incremental launching comprising: a pair
of opposing walls that form opposite sides of an opening and that
are configured to support loads associated with supporting a
plurality of static stress ribbon sections and forces that result
from launching the stress ribbon sections; a blister that is
located on a top surface of each of the opposing walls and
extending along at least a portion of the length of each opposing
wall, the blister configured to engage a bearing surface of an
anchorage panel of a stress ribbon section; and one or more
bearings installed on a surface of the blister that aid sliding of
the anchorage panel along the blister, wherein a plurality of
stress ribbon sections are constructed and launched onto the
opposing walls by one or more of pushing or pulling each of the
stress ribbon sections in a direction parallel to the length of the
opposing walls to slide the anchorage panels along the blisters,
each of the opposing walls supports an opposite end of each of the
stress ribbon sections.
3. The support structure of claim 2, wherein each of the plurality
of stress ribbon sections are constructed and launched
individually, launching of a subsequent stress ribbon section
causes the subsequent stress ribbon section to abut a previously
launched stress ribbon section and slides the anchorage panels of
the subsequent and previous stress ribbon sections along the
blisters of the opposing walls.
4. The support structure of claim 3, wherein the plurality of
stress ribbon sections abutted together form a stress ribbon
structure that covers the opening between the opposing walls.
5. An anchorage panel for a stress ribbon section comprising: a
downwardly extending protuberance that provides a bearing surface
for engaging a first blister of a construction fixture and a second
blister of a support structure, the first and second blisters
including an upwardly extending component that engages the bearing
surface, the engagement of the bearing surface and the first and
second blisters obstructs movement of the anchorage panel toward an
opening formed by the support structure; a cable duct extending
through the anchorage panel along a length thereof and configured
to accept a cable therein; and a cable anchorage system that
secures the cable within the cable duct and allows tensioning of
the cable, wherein the anchorage panel forms an end of a stress
ribbon section that includes a second anchorage panel at an
opposite end of the stress ribbon section, a plurality of cables
extending between the anchorage panel and the second anchorage
panel, and a plurality of deck panels installed on the plurality of
cables, and wherein the anchorage panel is slideable along the
first and second blisters to allow launching of the stress ribbon
section over the opening.
6. A stress ribbon structure constructed via incremental launching
comprising: a support structure for supporting a stress ribbon
section, the support structure including a pair of opposing walls
that define opposite sides of an opening and that are configured to
support loads associated with supporting a plurality of static
stress ribbon sections and forces that result from launching the
plurality of stress ribbon sections, wherein each of the opposing
walls includes a blister that is located on a top surface thereof
and extending along at least a portion of a length of each opposing
wall; a plurality of stress ribbon sections that include a pair of
anchorage panels, a plurality of cables, and a plurality of deck
panels, each of the plurality of stress ribbon sections having a
length and a width, the length being at least twice the width and,
the plurality of stress ribbons sections are abutted together along
their length to form a stress ribbon structure that covers the
opening between the opposing walls, wherein the anchorage panels
include a downwardly extending protuberance that provides a bearing
surface for engaging the blister of the support structure, the
blister including an upwardly extending component that engages the
bearing surface, the engagement of the bearing surface and the
blister obstructs movement of the anchorage panel toward the
opening and allows the anchorage panel to slide along the blister
in a direction perpendicular to the length of the stress ribbon
section.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S.
application Ser. No. 12/907,552 (filed on Oct. 19, 2010, and
issuing as U.S. Pat. No. 8,359,810), which is a continuation of
U.S. patent application Ser. No. 12/248,599 (filed Oct. 9, 2008 and
issued as U.S. Pat. No. 7,814,724), which claims priority to U.S.
Provisional Patent Application Serial No. 60/978,622 (filed on Oct.
9, 2007). All of the aforementioned are incorporated herein by
reference in their entirety.
BACKGROUND
[0002] A stress ribbon, or stressed ribbon, is one of the simplest
forms for long span structures and is based upon the iron chain
bridge developed in Asia over 2000 years ago. A typical stress
ribbon bridge is constructed with the use of high strength steel
cables or tendons, typically in the form of pre-stressing strands
between two upright support structures. The deck for stress ribbon
structures is typically reinforced concrete, but may be any
structural system that is capable of resisting compression forces
and has adequate axial stiffness. Initially, the deck system is
suspended from the cable system in an unstressed state, though the
weight of the deck serves to add tension to the cable system.
Subsequently, the steel cables or tendons are tensioned to put the
deck system in a compressive state, thereby creating a prestressed
(precompressed) structural system, with significantly increased
stiffness beyond the cable system alone. It is noted that, given
the plurality of cables in each section, some portion of the cables
may be used to support the weight of the deck and are termed
"bearing cables" and the remaining portions used to precompress the
deck and are therefore termed prestressing cables.
[0003] Incremental launching is a construction technique that has
been developed for construction of bridges in circumstances where
lifting activities are restricted or impossible, e.g., in
circumstances where the structure is too high (such as a bridge
spanning a deep valley or gorge) or where a busy highway or rail
corridor is spanned and interruption of traffic represents a severe
inconvenience. Through incremental launching, a portion, or
segment, of the structure is constructed in a fixed location and
pushed, or launched, over the feature to be spanned. During
construction, the partially completed structure has to function as
a cantilever resulting in increased load demands over those
required in the final configuration, where the structure is
supported at both ends. This typically requires a structure of
increased depth and strength in order to meet the additional load
demands during construction. Such structures must be, on average,
20% to 30% stronger and somewhat more costly as compared to
conventional construction.
BRIEF SUMMARY
[0004] The present invention generally relates to methods and
systems for building over an opening via a combination of stress
ribbon and incremental launching techniques. Temporary structures
are constructed in a staging area adjacent to a permanent
structure. Construction activities are generally restricted to the
staging area, thereby decreasing construction and equipment costs,
and increasing safety in the area within the opening over which a
structure is to be built. The structure is built in sections which
are subsequently incrementally launched from the temporary support
structures of the staging area to the permanent structure and over
the opening. Multiple sections are abutted together to form the
structure. One or more topping layers may be applied to the top of
the structure.
[0005] Additional objects, advantages, and novel features of the
invention will be set forth in part in the description which
follows, and in part will become apparent to those skilled in the
art upon examination of the following, or may be learned by
practice of the invention.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0006] The present invention is described in detail below with
reference to the attached drawing figures, wherein:
[0007] FIG. 1 is a perspective view of an incrementally launched
stress ribbon section according to an embodiment of the present
invention;
[0008] FIG. 2 is a side elevation view of one end of an
incrementally launched stress ribbon structure according to an
embodiment of the present invention;
[0009] FIG. 3 is a perspective view of an anchorage panel according
to an embodiment of the present invention;
[0010] FIG. 4 is a perspective view of deck panels of a stress
ribbon structure according to an embodiment of the present
invention;
[0011] FIG. 5A is a transverse cross-sectional side elevation view
of a deck panel according to an embodiment of the present
invention;
[0012] FIG. 5B is a cross-sectional side elevation view of the deck
panel of FIG. 5A taken along the line 5B-5B;
[0013] FIG. 6 is a transverse cross-sectional side elevation view
of two deck panels of adjacent sections of a stress ribbon
structure with topping layers according to an embodiment of the
present invention;
[0014] FIG. 7A is plan view of temporary structures, permanent
structures, and an opening over which a stress ribbon structure is
to be built according to an embodiment of the present
invention;
[0015] FIG. 7B is a side elevation view corresponding to FIG.
7A;
[0016] FIG. 8A is a plan view of anchorage panels and cables of a
stress ribbon section spanning across the opening according to an
embodiment of the present invention;
[0017] FIG. 8B is a side elevation view corresponding to FIG.
8A;
[0018] FIG. 9A is a plan view of deck panels being positioned on
the cables of the stress ribbon section according to an embodiment
of the present invention;
[0019] FIG. 9B is a side elevation view corresponding to FIG.
9A;
[0020] FIG. 10A is a plan view of a completed section of the stress
ribbon section that has been launched transversely onto the
permanent structures according to an embodiment of the present
invention;
[0021] FIG. 10B is a side elevation view corresponding to FIG.
10A;
[0022] FIG. 11 is a perspective view of the stress ribbon structure
according to an embodiment of the present invention having a
completed, launched section and a second section under
construction; and
[0023] FIG. 12 is a perspective view of the completed stress ribbon
structure according to an embodiment of the present invention.
DETAILED DESCRIPTION
[0024] The subject matter of embodiments of the present invention
is described with specificity herein to meet statutory
requirements. However, the description itself is not intended to
limit the scope of this patent. Rather, the inventor has
contemplated that the claimed subject matter might also be embodied
in other ways, to include different steps or combinations of steps
similar to the ones described in this document, in conjunction with
other present or future technologies. Moreover, although the term
"step" may be used herein to connote different elements of methods
employed, the term should not be interpreted as implying any
particular order among or between various steps herein disclosed
unless and except when the order of individual steps is explicitly
described. Further, the inventor has contemplated that the
variations in construction sites and practices are numerous and
that the claimed subject matter may be embodied in practices
utilizing machinery, materials, and construction methods not
described specifically herein, but that would be recognized by one
of skill in the art as equivalents.
[0025] Embodiments of the present invention provide methods and
systems for building over an opening via a combination of stress
ribbon and incremental launching technologies. In one aspect, a
method for building over an opening is described. A pair of
temporary support structures for supporting a stress ribbon section
are prepared. The stress ribbon section comprises at least two
anchorage panels, a plurality of cables and a plurality of
prefabricated deck panels. The stress ribbon section is constructed
by locating the anchorage panels on the support structures,
installing the plurality of cables across the opening, wherein the
cables are connected to and span between the anchorage panels, and
installing the plurality of prefabricated deck panels on the
plurality of cables. The cables are then tensioned and the stress
ribbon section is then moved or launched sideways over the
opening.
[0026] In another aspect, a system for incrementally launching a
stress ribbon structure over an opening is disclosed. The system
comprises a plurality of stress ribbon sections each comprising,
two anchorage panels, a plurality of cables, and a plurality of
prefabricated deck panels. Temporary support structures for
supporting each end of a stress ribbon section, and a permanent
support structure for supporting the stress ribbon structure are
also components of the system. The plurality of stress ribbon
sections are constructed by locating an anchorage panel on each
temporary support structure, installing the plurality of cables
across an opening between the anchorage panels, installing the
plurality of prefabricated deck panels on the plurality of cables,
and tensioning one or more of the plurality of cables. The stress
ribbon section is subsequently launched in a direction transverse
to its length onto the permanent support structure, and the
plurality of stress ribbon sections abut along lateral edges to
form the stress ribbon structure.
[0027] In yet another aspect, a method for building a stress ribbon
structure over an opening via incremental launching is disclosed. A
permanent support structure for supporting the stress ribbon
structure is provided, and temporary support structures are
constructed in a staging area adjacent to the permanent support
structure, the temporary support structure being capable of
supporting each end of a section of the stress ribbon structure. A
plurality of sections are prepared by locating anchorage panels on
each temporary support structure, installing a plurality of cables
between the anchorage panels, wherein each cable further comprises
a plurality of strands, and installing a plurality of prefabricated
deck panels on the plurality of cables. The section is launched in
a direction transverse to the length of the section and abuts
adjacent sections. One or more of the plurality of strands in the
plurality of cables are tensioned prior to launching, after
launching, or both prior to and after launching, and one or more
topping layers are applied.
[0028] Referring initially to FIG. 1, a portion of an incrementally
launched stress ribbon structure 100 is depicted. Temporary support
structures 102 are erected adjacent to permanent structures 104. As
illustrated, three launched stress ribbon sections 106 are
supported on the permanent structures 104 while an unlaunched and
under construction stress ribbon section 108 is supported on the
temporary support structures 102. Both the launched and unlaunched
stress ribbon sections 106 and 108 are constructed with anchorage
panels 110, a plurality of cables 112, and a plurality of deck
panels 114.
[0029] The temporary support structures 102 may be constructed in
any design or configuration capable of supporting each end of an
unlaunched stress ribbon section 108 and may have a foundation
system (deep or shallow) capable of resisting the forces associated
with stress ribbon construction, or may employ other desirable
construction techniques. The temporary support structures 102 must
be capable of withstanding large horizontal forces in the direction
of cables 112. The size and configuration of the temporary support
structures 102 may be determined based on the size, weight, and
other characteristics of the unlaunched stress ribbon section 108,
but generally the length between temporary support structures
matches the span of the stress ribbon structure 100, and the width
of the temporary support structures is a function of the width of
the section 108. Typically, the temporary support structures 102
are constructed to provide ease of removal upon completion of the
stress ribbon structure 100, but may be constructed or retained as
integral components of the permanent structure 104.
[0030] In one embodiment, the temporary support structures 102 are
constructed from steel beams, welded, bolted, or riveted together
in a generally right triangular format, as depicted in FIG. 1. A
foundation system including compressing elements, such as drilled
shafts, driven piles or spread footings (not shown), and tension
elements, such as rock anchors (not shown), are used to anchor the
temporary support structures 102 and provide a substructure system
that is adequate to support all loads associated with the
unlaunched sections 108.
[0031] With continued reference to FIG. 1, the temporary support
structures 102 are constructed directly adjacent to the permanent
structure 104 leaving very little, or no gap between them. The
location adjacent to the permanent structure 104 is denoted as a
staging area 116, and location of the temporary support structures
102 therein allows nearly all construction activities for erecting
the stress ribbon structure 100 to be completed outside, or away
from the permanent structure 104.
[0032] The permanent structure 104 is any structure, or structures,
capable of supporting the stress ribbon structure 100. The
permanent structure 104 may have any design, span, height, depth,
or other characteristic for which a stress ribbon structure 100 can
be constructed. As depicted herein, the permanent structure 104 may
be such that the stress ribbon structure 100 provides a roof over
an opening 118 outlined by the structure 104. In another embodiment
the permanent structures may comprise bridge abutments for which a
stress ribbon structure may comprise a bridge deck, among many
other possible embodiments.
[0033] Again referring to FIG. 1, the launched sections 106 and the
unlaunched section 108 are identical in construction except that
the unlaunched section is currently supported by the temporary
support structures 102 and the launched sections are supported by
the permanent structure 104. Unlaunched sections 108 are
constructed on the temporary support structures 102 and are then
launched by pushing or pulling the section from the temporary
support structure onto the permanent structure 104. The pushing or
pulling may be completed by many methods including for example, but
not limitation, winching and jacking. The launching of the
unlaunched section 108 forces the section against launched sections
106, thereby moving all of the sections along the permanent
structure 104 and away from the temporary support structures 102.
Following launching, the unlaunched section 108 becomes a launched
section 106 and another unlaunched section may be constructed on
the temporary support structures 102.
[0034] Referring now to FIGS. 1 and 2, a blister 202 is depicted
along a top surface of both the temporary support structure 102 and
the permanent structure 104. The blister 202 is a raised feature
located along the full length of the temporary support structure
102 and permanent structure 104 which engages the anchorage panels
110. The engagement retains the anchorage panels 110 by providing
opposing surfaces between the blister 202 and the anchorage panel
110, thereby supporting the sections 106 and 108.
[0035] One or more bearings 204 may be inserted between the
opposing surfaces of the blister 202 and the anchorage panel 110.
The blister 202 surfaces are oriented such that they are aligned
perpendicular to the final force in the stress ribbon structure
100, thereby minimizing the rotational demands on the bearings 204.
The bearings 204 may be comprised of any suitable material, such as
for example, but not limitation, Neoflon.RTM. or Kel-F.RTM.
produced by Daiken Industries of Japan, or neoprene elastomeric
compounds, which may be combined with a Teflon.RTM. sliding surface
as manufactured by DuPont Corporation of Wilmington, Del., among
others, and may allow the anchorage panels 110 to more easily slide
along the blister 202 during incremental launching. The bearings
204 in conjunction with the blister 202 and anchorage panels 110
may also allow the anchorage panels 110 and therefore the sections
106 and 108 to rotate about the blister to a sufficient degree in
order that bending stress in the stress ribbon structure 100 is
minimized. The rotational freedom is principally oriented in the
vertical direction and may be useful in aligning abutting sections
106 and 108, among other uses, as will be described in greater
detail below.
[0036] With additional reference to FIG. 3, the anchorage panels
110 are located at each end of the sections 106 and 108. The
anchorage panels 110 are designed to transfer the force from the
sections 106 and 108 to the temporary support structure 102 and the
permanent structure 104. The anchorage panels 110 provide a bearing
surface 302 for engagement with the blisters 202 to retain the
sections 106 and 108 in position and to allow movement of the
sections during launching and alignment. The anchorage panels 110
may have any desired profile with a downward extending protuberance
that provides the bearing surface 302 and proper engagement with
the blister 202.
[0037] One or more cable ducts 206 are generally located within the
anchorage panel 110 for inserting and installing one or more cables
112 through the anchorage panel 110 in the direction of the section
106 or 108 and securing the cables thereto. A plurality of cable
anchorages 208 may be cast adjacent a face 210 of the anchorage
panel 110. A cable anchorage system, such as a wedge-plate system,
among others, is used to anchor the cables within the cable
anchorage 208.
[0038] The anchorage panels 110 may be constructed from reinforced
concrete or from any other suitable materials, or combinations
thereof including metals, composites, or ceramics, among others. As
depicted in FIG. 3, internal reinforcements 304 may be provided in
any appropriate configuration and may extend from the anchorage
panels 110 to engage adjacent sections 106 and 108 or as topping
interface reinforcements 306 to serve as shear interface
reinforcement and to provide for composite behavior with a topping
material (described below).
[0039] The interface reinforcements 306 may be used to connect to
and reinforce one or more topping layers (discussed below) applied
to the top of the sections 106 or to the stress ribbon structure
100. The interface reinforcements 306 comprise shear transfer
reinforcements, or stirrups which transfer forces between the
sections 106 and any topping layers. Further, utilizing interface
reinforcements 306 to connect to a topping layer may also provide
integration or connection of the sections 106 and 108 together.
Interface reinforcements 306 may be of any shape, form or
configuration compatible with the construction of the stress ribbon
structure 100 and may comprise generally U-shaped sections of steel
reinforcing bar, among others.
[0040] The cables 112 (also known as tendons) span between opposing
anchorage panels 110 and support the deck panels 114. The cables
112 may comprise any structural element capable of resisting
tension forces, such as, for example but not limitation, cable,
chain, or rope, among others, suitable for application in the
sections 106 and 108. As depicted in FIG. 3, the cables 112 may be
further comprised of a plurality of strands 308 or wires. Utilizing
cables 112 comprised of strands 308 provides the capability to
tailor the tension in each cable by individually tensioning each
strand 308 therein. Cables 112 of this form also offer the ability
to replace individual strands 308 while the cables are in use
supporting the structure.
[0041] Referring now to FIGS. 4-6, the deck panels 114 of the
stress ribbon structure 100 are depicted. The deck panels 114 are
generally square or rectangular in overall shape, but may have any
form, shape, or design suitable for construction of the stress
ribbon structure 100. Such designs may accommodate various
toppings, such as, for example, but not limitation, concrete,
asphalt, rubber, rock, or soil, among others. Designs are also
conceivable that may aid in the installation of components or
layers on the underside of the stress ribbon structure 100, such
as, HVAC, electrical, plumbing, lighting, scaffolding, catwalks,
overhead crane components, or moisture barriers, among others. The
deck panels 114 may be constructed from any suitable materials
capable of resisting compression forces and applicable for use in
the stress ribbon structure 100, including, but not limited to,
reinforced concrete, composites, and metals, among others.
[0042] The deck panels 114 may be pre-fabricated off site or may be
fabricated as needed on the construction site. Any fabrication
method may be utilized, including for example, a process of match
casting in which deck panels 114 are cast from concrete using other
adjacent deck panels as at least part of the casting mold. Such a
process provides the added benefit of insuring proper fit between
deck panels 114.
[0043] The deck panels 114 have a plurality of cable channels 402
cast, cut, or otherwise formed in the top surface of the panels for
accepting a plurality of cables 112. The cable channels 402 run
generally parallel to one another and extend the full dimension of
the deck panel 114 in the direction of the stress ribbon section
108 into which the deck panel 114 will be incorporated. In other
embodiments, the cable channels 402 may be located within the panel
or along the underside of a deck panel 114.
[0044] A cable channel 402 generally has a width and depth
sufficient to fully receive a cable 112 into the channel such that
the top of the cable is at or below the top surface of the deck
panel 114, as depicted in FIGS. 5A and B. The cable 112 may be
retained within the cable channel 402 by a plurality of pins 404
inserted over the top of the cable channel and held in place by a
plurality of tie down anchors 406. The pins 404 are typically round
steel rods of sufficient diameter and material properties to
support all, or a portion of the weight of a deck panel 114. The
round shape of pins 404 allows the pins to roll along the top of
the cables 112 to aid in moving the deck panels 114 along the
cables. The tie down anchors 406 may be any component or fixture
affixed to, or formed at or near the top surface of the deck panel
114 for accepting and retaining the pins 404. For example, the tie
down anchors 406 may comprise steel tabs bolted to, or cast in the
top surface of the deck panel 114 on adjacent sides of a cable
channel 402. In other embodiments, for example the pins may have a
non-circular cross-sectional shape and may be anchored to a deck
panel without the use of tie down anchors 406.
[0045] In FIG. 5A a cross-sectional transverse side elevation view
of a deck panel 114 depicts cables 112 located within the cable
channels 402 and retained therein by pins 404 and tie downs 406. A
plurality of internal reinforcements 502 as well as a plurality of
topping interface reinforcements 504 is also depicted. The internal
reinforcement 502 may comprise steel reinforcing bar or any other
suitable components or materials for reinforcing the deck panel
114. The internal reinforcements 502 may also extend out of the
deck panel 114 to provide one or more features for connecting deck
panels or sections 106 together or for moving or manipulating the
deck panels, among others.
[0046] As best depicted by FIG. 6, the topping interface
reinforcements 504 extend from the top surface of the deck panel
114 and may be utilized to connect one or more topping layers 602
applied to the sections 106 or to the stress ribbon structure 100.
The topping interface reinforcements 504 may extend into the deck
panel 114 and engage one or more of the internal reinforcements 502
to aid in retaining the interface reinforcements 504 in the deck
panel 114. Also as depicted in FIGS. 5A and 6, the topping
interface reinforcements 504 may extend from the top surface of the
deck panel as a stirrup, or generally U-shaped form, among a
variety of other possible formations. Such topping interface
reinforcements 504, may further be used as a location to which one
may secure topping reinforcements 604, such as reinforcing bar, for
reinforcing the topping layer 602. The topping reinforcements 604
may connect to, or intertwine with, the topping interface
reinforcements 306 and may be placed parallel and/or transverse to
the deck panels 114, as depicted in FIG. 6, or may be oriented in
any other desired fashion. As such, the topping interface
reinforcements 504 also provide shear transfer reinforcement
between the sections 106 and 108 and any topping layers 602.
[0047] As described above, the topping layer 602 is generally
comprised of concrete reinforced by the topping reinforcements 604
and topping interface reinforcements 306; however, it may also be
constructed from asphalt, rubber, rock, or soil, among other
possible materials. The one or more topping layers 602 may be
applied by multiple methods and by a variety of sequences. The
topping layer 602 may be applied to an unlaunched section 108 or to
one or more launched section 106. The topping layer 602 may be
applied to individual sections 106 and 108, one at a time, to two
or more sections at a time, to the entire stress ribbon structure
100 all at once, or any combination thereof. The stress ribbon
structure 100 design and construction demands may determine how and
when to apply the topping layers 602.
[0048] Additionally, the topping layer or layers 602 may be
utilized to link the sections 106 together into a unified,
composite structure by providing a continuous component across the
plurality of sections 106. An additional layer or membrane 606 may
be applied on top of the one or more topping layer 602 to provide a
water barrier, reflective layer, chemical barrier, or corrosion
inhibiting layer, among many other possibilities.
[0049] With reference now to FIGS. 7-10, a method for building over
an opening 118 via a combination of stress ribbon and incremental
launching techniques is depicted according to an embodiment of the
present invention. In FIGS. 7A and B, portions of a permanent
structure 104 are shown along, and form opposite sides of, an
opening 118. A staging area 118 is depicted outside and adjacent to
the opening 116 and the permanent structures 104. Temporary support
structures 102 are erected adjacent to the permanent structures 104
and in the staging area 116. Very little or no space is left
between the portions of the temporary support structure 102 and the
permanent structure 104 that form the blister 202 in order to
provide a continuous surface along which the sections 108 may be
launched.
[0050] In FIGS. 8A and B, anchorage panels 110 are placed on each
of the temporary support structures 102 and, in this embodiment,
four cables 112 are installed between the anchorage panels. The
cables 112 are inserted into the cable ducts 206 (see FIG. 3) of
the anchorage panels 110 and are fixed within the cable anchorages
208. A hydraulic jacking system is used to achieve an initial
tension and adjust the sag in the cables 112 by applying a
prescribed tension force on individual strands 308 of the cables
and to fix the position of the cable within the anchorage 208 with
the use of individual strand wedges (not shown), among other
anchorage systems. Cables may be prefabricated from individual
strands 308 into a complete system and inserted into the cable duct
206, or may be installed strand by strand 308 using a winch and a
messenger cable shuttle system with the cable duct 206 as the
conduit for strand installation.
[0051] The cables 112 hang between the anchorage panels 110 in the
shape of a Catenary arc, as depicted in FIG. 8B. A linear
relationship exists between the tension on the cables 112 and the
amount of sag in the cables. Therefore, the tension may be adjusted
to produce a desired sag in the cables 112, and eventually in the
sections 106 an 108. In other embodiments, the shape of the arc may
also be altered by adding mass or weight at points along the arc
causing the shape to deviate from the Catenary arc shape.
[0052] FIGS. 9A and B depict the installation of a plurality of
deck panels 114 on the cable 112 in the staging area 116. Various
methods may be utilized to install the deck panels 114. The deck
panels 114 may be lifted up to the cables 112 by a crane, but other
methods such as a pulley system that rides on top of the cables
equipped with a hoist may also be used, among a variety of others.
The deck panels 114 may be lifted into position at any point along
the cables 112. The deck panels 114 may each be lifted at
individual locations at which they will remain along the cables
112, or more than one deck panel may be lifted at a single location
along the cables.
[0053] Once lifted to the cables 112, the deck panels 114 may be
connected thereto by inserting each cable 112 into a respective
cable channel 402 and then inserting a plurality of pins 404 over
the cables and across the cable channels 402 (see FIGS. 4-6). The
pins 404 may be held into position by tie down anchors 406 located
on each side of the cable channels 402.
[0054] If more than one deck panel 114 is lifted at a single
location along the cables 112 then, after each deck panel is
connected to the cables, it may be pulled or pushed along the
cables to its final location using a winch, hoist, or jacks, among
other methods. Such a winch, hoist, or jack, among others, may be
mounted on the temporary support structure 102, the permanent
structure 104, or may be separate therefrom. The pins 404 may aid
in moving the deck panels 114 into position by rolling or sliding
along the cables 112. Grease or other lubricants may be applied to
the cables 112 and pins 404 to further assist in the positioning.
Further, depending on the location at which the panels 114 are
connected to the cables 112, gravity may be used to move the panels
114 from their connection location toward the center of the cables
114.
[0055] With all of the deck panels 114 connected to the cables 112
and in the desired position, the cables may be tensioned in the
same manner as described above using a hydraulic jack to tension
each strand 308 individually, among other methods, such as loading
the cables 112. One or more of the cables 112 may be drawn into
tension to create compressive forces between the anchorage panels
110 and each of the deck panels 114 to pre-compress the panels.
Placing the panels 110 and 114 in a compressed state causes the
stress ribbon section 108 to become a more efficient structural
system, because the system stiffness is predominated by unloading
the precompression in the section 108, which is nearly constant
precompression through the entire deck panel 114 and anchorage
panel 110 system, instead of only the tension stiffness of the
supporting cables 112. As such the section 108 has substantially
more stiffness than the cable system supporting the weight of the
precast panels, and is better at resisting additional loads,
especially unbalanced loads. This system may have similar strength
and stiffness as the final stress ribbon structure 100.
[0056] Additionally, each of the cables 112 or the individual
strands 308 therein may be tensioned to different degrees. One or
more of the cables 112 or strands 308 may be used as tensioning
tendons to apply the compression for pre-stressing the panels 110
and 114 and the section 108. Conversely, one or more of the
remaining cables 112 or strands 308 may be employed as bearing
tendons which are imparted with a lesser degree of tension as
compared to the tensioning tendons, and which aid in bearing the
weight of the structure, among other purposes. It is noted that
tensioning of the cables 112 may directly impact the geometry of
the unlaunched section 108 and may introduce rotation at the
bearings 204. As described previously, the bearings 204 may
accommodate this rotation as well as provide an instrument for
aiding in launching of the sections 108.
[0057] Referring now to FIGS. 10A and B, an unlaunched section 108
(depicted in FIGS. 9A and B) may be launched. The section 108 may
be launched by pushing or pulling the section 108 sideways over the
opening 118 with hydraulics, pneumatics, winches, hoists, or by
another method. Generally, a force is applied at, or near each end
of the section 108 along a lateral face of the anchorage panel 110.
The force is applied in a direction parallel to the length of the
blister 202 and generally transverse to the length of the section
108.
[0058] The bearing surfaces 302 (see FIG. 3) of the anchorage
panels 110 slide along the bearings 204 placed between the bearing
surfaces 302 and the blisters 202, thereby allowing the section 108
to move along the blisters 202 from the temporary support
structures 102 to the permanent structures 104. The unlaunched
section 108 thus becomes a launched section 106 and construction
can begin on the next unlaunched section, as depicted in FIG.
11.
[0059] As subsequent sections 108 are launched they will abut
previously launched sections 106 along their length and the
launching process will cause the launched sections to move further
along the blisters 202 and the permanent structure 104. The
construction and launching processes are repeated until all
sections 108 are launched.
[0060] Differences in the sag of adjacent sections 106 and 108 may
be noticed before or after launching. The tension in the cables 112
and strands 308 may be adjusted to accommodate these differences
and to adjust the sag of the sections. As stated previously, the
sag has a linear relationship with the tension and therefore, the
tension may be increased to reduce the sag of a section 106 or 108
or may be decreased to increase the sag. Further, the combination
of the anchorage panels 110, blisters 202 and the bearings 204
allow the ends of the sections 106 and 108 to rotate about the
blisters 202 and thereby allow the sag of the sections 106, 108 to
be adjusted without damaging, reconstructing or adjusting the
temporary support structures 102 or the permanent structure
104.
[0061] Sealants and glues, such as, for example but not limitation,
epoxies, resins, fibers, fabrics, or rubber gaskets, among others,
may be applied between sections 106 and 108 and between panels 110
and 114 prior to, or after launching. Such sealants and glues may
aid in bonding the sections 106 and 108 and panels 110 and 114
together, and may serve to prevent leaks, among other uses.
[0062] Having launched all necessary sections 108, one or more
topping layers 602 may be applied to the launched sections 106, as
depicted in FIG. 12. Topping reinforcements 604 (see FIG. 6), such
as, for example but not limitation, steel reinforcing bar, may be
installed on the sections 106 and across sections to tie them
together in any suitable manner, but generally are applied in a
grid layout. The grid of topping reinforcements 604 may engage and
intertwine with topping interface reinforcements 306 and 504 on the
top of the anchorage panels 110 and deck panels 114 respectively,
that comprise the sections 106. In the present embodiment, a
topping layer 602 is comprised of concrete, but any other suitable
material may be utilized as described previously.
[0063] The topping layer 602 may be applied in stages or to the
entire structure 100 at once, as may be required by construction
demands. Generally, the topping layer 602 is applied across one or
more sections at a time such that seams between portions of the
topping layer are staggered with seams between adjacent sections
106. Such a method minimizes seams or gaps that penetrate the depth
of the structure and connects the sections 106 to one another.
[0064] Alternatively, topping layers 602 may be applied to
individual sections 108 prior to launching or across one or more
launched sections 106 prior to completion of all launching steps.
Advantages for each of these methods exist, for example applying
the topping layers 602 after completion of launching requires less
force for launching due to the sections having less weight without
the topping layer. Construction demands, costs, and design may
determine the sequence of the steps.
[0065] Conversely, or in addition to one or more topping layers
602, a system of transverse post-tensioning may be utilized to link
the sections 106 together. A series of cables or tendons, among a
variety of other components, may be installed above, below and/or
through the sections 106 in a manner that extends between two or
more sections. Tension may be applied to the cables to draw the
sections 106 together and to retain the sections in position.
[0066] After application of one or more topping layers 602, one or
more membranes 606 may also be applied. The membranes 606 may
comprise any suitable substance or structure for achieving the
design and construction demands of the membrane, including for
example, a rubber, plastic, composite or other material for
providing a moisture barrier, among others.
[0067] An additional, tensioning process may be carried out after
application of the one or more topping layers 602 or membrane 606.
Such a process may be utilized to adjust the tension for changes in
the weight of the structure 100 due to application of the toping
layers 602 or membrane 606, or may be utilized to adjust the amount
of compression and pre-stress the structure is under. Furthermore,
the tension of the cables 112 and strands 308 may be adjusted
throughout the life span of the structure 100.
[0068] Many variations in the sequence of steps, construction
materials, equipment, and structure design are possible and
necessary for tailoring aspects of present invention for use in the
wide array of construction and design applications available.
Construction demands, costs, equipment, and design, among other
factors, may determine such variables to promote the many
advantages of the present invention.
[0069] Such advantages may include the capability to lift deck
panels 114 at a single location and then push or pull them into
position. By such a method, only a single crane or lifting system
need be provided, and it may not require relocation during
construction. Also, the crane or lifting system may be
advantageously located and oriented such that the smallest range of
motion for lifting and placing the deck panels 114 is required.
Additionally, the workflow of material may be more easily setup and
processed because it can be based around the single lifting
location. All such advantages may increase the efficiency of the
worksite and decrease equipment costs by reducing the size and
number of cranes, or other lifting apparatus, and the amount of
worksite preparation and setup, among others. Further, the safety
of the worksite may also be increased because the lifting
activities may be contained within fewer and smaller areas.
[0070] Additional advantages of embodiments of the present
invention include the capability for all, or nearly all, of the
construction process to occur within the staging area 116. The
cranes, or other lifting systems, and other materials, equipment,
and personnel may be contained within the staging area 116.
Further, as sections 108 are launched, they may be in a nearly
completed state. The launched sections 106 or the partially
completed stress ribbon structure 100 may have the same, or nearly
the same strength, rigidity, safety, and fire safe characteristics,
among other characteristics, as the fully completed stress ribbon
structure. Thus, any activities, people, equipment, or otherwise
that are located within the opening 118 may safely continue and
remain within the opening during the construction process.
[0071] Additionally, the construction activities that must take
place on top of the sections 106 may have increased safety with
respect to the rigidity and completeness of the sections. Because
the sections 106 have the same, or nearly the same, strength and
rigidity characteristics as the completed structure 100 and because
they comprise very few components, construction personnel and
equipment may access the top of the sections 106 without the fears
and dangers associated with other structures such as, falling
through the structure, loose or missing components of the
structure, and incomplete structural portions of a structure, among
others.
[0072] In one embodiment of the present invention the stress ribbon
structure may form a roof over a rail yard as depicted in FIGS. 11
and 12. The incrementally launched stress ribbon structure 100 may
be well suited to such an application due to the advantages of
launching over an opening comprising the rail yard without the
necessity to halt rail traffic or activities in the rail yard
during construction. Further, due to the great strength and
flexibility that may be inherent in a design of the structure 100,
very large spans may be achieved, as well as accommodation of
various components above or below the structure, such as, for
example, a park placed on top of the structure. Additionally, the
rotational flexibility of the bearing 204 system at the anchorage
segments 110 and the ability to alter the geometry of the structure
100 through tensioning may provide adaptability of the structure to
various design concepts.
[0073] In another embodiment of the present invention the stress
ribbon structure may comprise a bridge or roof structure to support
pedestrian or vehicular traffic or wind, water, snow and ice loads.
As described above, the adaptability of the stress ribbon structure
and the capability to provide a stiff structural system for long
uninterrupted spans may be very useful for such structures.
[0074] From the foregoing, it will be seen that this invention is
one well adapted to attain all the ends and objects hereinabove set
forth together with other advantages which are obvious and which
are inherent to the structure.
[0075] It will be understood that certain features and
subcombinations are of utility and may be employed without
reference to other features and subcombinations. This is
contemplated by and is within the scope of the claims.
[0076] Since many possible embodiments may be made of the invention
without departing from the scope thereof, it is to be understood
that all matter herein set forth or shown in the accompanying
drawings is to be interpreted as illustrative and not in a limiting
sense.
* * * * *