U.S. patent application number 13/148455 was filed with the patent office on 2011-12-22 for structural member.
Invention is credited to Rob Wallace.
Application Number | 20110308197 13/148455 |
Document ID | / |
Family ID | 42561311 |
Filed Date | 2011-12-22 |
United States Patent
Application |
20110308197 |
Kind Code |
A1 |
Wallace; Rob |
December 22, 2011 |
STRUCTURAL MEMBER
Abstract
A structural member (20), including a longitudinally extending
core (22), and at least two longitudinally extending ribs (24, 26,
28). Each rib (24, 26, 28), in profile, extends outwardly from the
core (22) to an outer rib edge (30, 32, 34). The member (20) also
includes a receiving aperture (36) in a first end (38) of the
member (20) for receiving an end of an adjacent member (42).
Inventors: |
Wallace; Rob; (Victoria,
AU) |
Family ID: |
42561311 |
Appl. No.: |
13/148455 |
Filed: |
February 8, 2010 |
PCT Filed: |
February 8, 2010 |
PCT NO: |
PCT/AU2010/000126 |
371 Date: |
September 8, 2011 |
Current U.S.
Class: |
52/846 ;
52/848 |
Current CPC
Class: |
E04C 2003/0434 20130101;
E04C 3/32 20130101; E02D 5/523 20130101; E04C 2003/0478 20130101;
E02D 5/24 20130101; E04C 2003/0413 20130101 |
Class at
Publication: |
52/846 ;
52/848 |
International
Class: |
E04B 1/58 20060101
E04B001/58; E04C 3/00 20060101 E04C003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 11, 2009 |
AU |
2009900559 |
Claims
1. A structural member, comprising: a longitudinally extending
core; at least two longitudinally extending ribs, with the ribs
extending from at least proximate a first end of the member to at
least proximate a second end of the member; with each rib, in
profile, extending outwardly from the core to an outer rib edge;
and a receiving aperture provided in a first end of the member for
receiving an end of an adjacent structural member, in an
arrangement such that at least one rib of the structural member at
least partially overlaps with at least one rib of the adjacent
structural member.
2. A structural member according to claim 1, wherein the first end
comprises a first connecting arrangement for connecting the first
end to the end of the adjacent structural member.
3. A structural member according to claim 2, wherein the first
connecting arrangement comprises one or more fastener receiving
apertures provided in at least one rib.
4. A structural member according to claim 3, wherein the structural
member comprises a second connecting arrangement for connecting the
second end to another adjacent structural member.
5. A structural member according to claim 1, wherein the first end
comprises an abutment shoulder provided on at least one of the ribs
and core for alignment of the structural member with the adjacent
structural member.
6. A structural member according to claim 1, wherein the structural
member comprises 2, 3 or 4 longitudinally extending ribs.
7. A structural member according to claim 1, wherein each rib, in
profile, tapers from the outer edge to the core.
8. A structural member according to claim 1, wherein the structural
member is one of a pile section, pile, strut, column, beam or
portion thereof.
9. A structural member according to claim 1, wherein each rib, in
profile, is generally straight
10. A structural member according to claim 1, wherein each rib, in
profile, is tapered.
11. A structural member according to claim 1, wherein each rib, in
profile, is curved or bent.
12. A structural member according claim 1, wherein the ribs are
substantially equidistantly spaced about the core.
13. A structural member according to claim 1, wherein, in profile,
the ribs generally define an X, Y or S shape.
14. A structural member according to claim 1, when manufactured
from two or more angled sections.
15. A structural member according to claim 1, wherein the receiving
aperture is a slot or slit.
16. (canceled)
Description
[0001] The present invention relates very broadly to the building
and construction industries. More particularly, the invention
relates to a structural member for use in the building and
construction industries and will herein be described generally in
that context. It is to be appreciated, however, that the invention
may have broader application.
[0002] Reference hereinafter will be generally made in the context
of the structural member being in the form of a building pile
section and a pile constructed from two or more pile sections. It
is to be appreciated that the invention could adopt any other
suitable form, including a building column, strut, beam or section
thereof.
[0003] Structural members in the form of piles and pile sections
are used widely in the construction industry both in Australia and
overseas to provide deep foundations for supporting buildings,
bridges and other structures.
[0004] Conventional piles include timber piles, reinforced (or
pre-stressed) concrete or steel piles.
[0005] Piles are typically driven by means of a hammer piling
device into the ground to a depth at which the pile develops enough
resistance to support the required load. If the pile is driven into
the ground a sufficient distance to rest against hard strata such
as rock then it is described as being end-bearing. Often though
this is not possible and so load capacity of the pile is achieved
by sufficient friction having been generated between the driven
pile and the surrounding soil.
[0006] It is typical practice in the construction industry to carry
out a geotechnical investigation prior to designing a structure.
Various investigation techniques are possible, with a common
technique being the boring of test holes at the proposed site in
order to obtain samples for laboratory analysis. The information
gained enables the design of pile parameters including pile type,
size and length. Unfortunately, regardless of the number of test
holes bored and the level of sophistication in analyzing the
samples, the results obtained are at best only a prediction. This
is, at least in part because soil and other conditions can vary
over the site and so some uncertainty is inherent in such
analysis.
[0007] Irrespective of the conventional pile type concerned, pile
cross-sections are usually constant along the length of the pile,
except in the case of timber piles, which generally naturally
taper. Round cross-sections are common for timber and concrete
piles, but concrete piles may also be of square, hexagonal and
octagonal cross-sections. Steel piles most commonly have an
H-section, but other shapes are also used, including round steel
pipes.
[0008] Piles are typically several metres in length. Timber and
steel piles are normally available in stock lengths up to 12 or 15
metres, in standard length increments of 1 to 2 metres. Concrete
piles are generally made to order, and can be made to any length,
but are limited in a practical sense by transport and handling
considerations. It is known to the applicant to allow for pile
lengths to be slightly greater than anticipated or calculated, as
it is far more cost effective to allow an extra metre or so of pile
length to reduce the risk of the pile being too short, thus
incurring the time and cost of joining together two pile sections
in an end-to-end arrangement. In this regard, it is to be
appreciated that significant time and cost is involved in aligning
and connecting together conventional pile sections.
[0009] Piling contractors generally prefer pile lengths of up to 12
metres, as this is the length that can be readily transported,
handled and accommodated in existing pile driving rigs. After
driving each pile until the specified load capacity is achieved the
pile is cut off and the excess length discarded.
[0010] Regardless of predictions made by even the most
sophisticated methods, piles must actually develop adequate load
capacity, verified at the time of driving. For end bearing piles
this is straightforward as the pile is driven to "refusal", at
which point it comes to a sudden definite halt against hard strata.
For friction piles, pile capacity has traditionally been verified
by calculation using a formula relating parameters such as pile
mass, and hammer mass, height of fall and penetration per blow of
the pile driving rig. Modern sophisticated methods using
instrumentation and computers enable more accurate, but still far
from perfect, predictions.
[0011] Extension of conventional pile lengths is time consuming and
costly in terms of material and labour. This is compounded by costs
associated with delay to construction activities, with expensive
crew on stand-by. For very deep foundations, joining of pile
sections is unavoidable and various types of connectors have been
developed for both timber and concrete pile sections, but they are
relatively expensive. For steel pile sections, butt welding is the
normal pile section connection method, but is also expensive, due
to the time taken to prepare the pile section ends, involving
grinding large bevels and making numerous weld passes. The
difficulty and high cost of joining pile sections means that pile
driving contractors seek to maximize pile section lengths, which
necessitates larger pile driving rigs. As well as being more
expensive, large pile driving rigs are more costly to transport and
set up on site.
[0012] Piles usually develop more load capacity with time
(generally known as "set-up"), as the disturbed soil consolidates
around the pile and bonds to it, and the lubricating affect of the
ground water diminishes. Even if pile driving is interrupted for
only a short period of time, as when splicing on an extra pile
section length, much greater effort is required when driving
restarts. Over the long term the pile capacity usually increases
much more because the soil bonds to the pile.
[0013] The applicant has recognized a need for improvement in piles
and also an improvement in connecting pile sections together.
Numerous designs exist for connecting concrete pile sections, few
for timber pile sections, but hardly any for steel pile sections.
This may be due to the prevailing view in the industry that, unlike
timber and concrete, steel can easily be joined by butt welding.
However, aligning and butt welding steel pile sections together is
time consuming and expensive, due to the time taken to prepare the
pile section ends.
[0014] It would therefore be desirable to provide an alternate and
potentially improved pile and/or pile section design.
[0015] It would also be desirable to provide a pile and/or pile
section design that provides a less time consuming and more cost
effective arrangement for the connection of pile sections than
currently available.
[0016] The discussion of acts, materials, devices, articles and the
like above is included in this specification solely for the purpose
of providing a context for the present invention. It is not
suggested or represented that any or all of these matters formed
part of the prior art base or were common general knowledge in the
field relevant to the present invention as it existed in Australia
before the priority date of each claim of this application.
[0017] According to the present invention, there is provided a
structural member. The structural member includes a longitudinally
extending core and at least two longitudinally extending ribs. Each
rib, in profile, extends outwardly from the core to an outer rib
edge. The structural member also includes a receiving aperture
provided in a first end of the member for receiving an end of an
adjacent structural member.
[0018] The aperture may be a slot, slit or other suitable form.
[0019] In a preferred form, the first end of the structural member
includes a first connecting arrangement for connecting the first
end to the end of the adjacent structural member.
[0020] The connection of structural members is desirable, because
the members can be manufactured in standard lengths and be
subsequently connected end-to end to provide an overall structure
of desired length.
[0021] The provision of a receiving aperture and first connecting
arrangement is most advantageous because it allows for the first
end of the member to nest with the end of the adjacent member. As
such, the member and adjacent member may be connected by way of a
lap joint, so as to provide a robust and durable connection between
the structural member and adjacent member.
[0022] The provision of an aperture also facilitates relatively
easy alignment of the structural members, in situ, if required. In
this regard, the second longitudinal end of the structural member
may be driven into the ground by a suitable driving and/or piling
device. The height of the structural member extending from the
ground may be insufficient for the desired purpose, such that
additional height is required. If so, then a second member can
relatively easily be aligned and located on top of and then
connected to the upper (first) end of the structural member to
increase the overall height to that required.
[0023] The first connecting arrangement may include one or more
fastener receiving apertures provided in at least one rib, such
that the overlapping ends of adjacent members may be fastened
together using bolts or other suitable fasteners.
[0024] It is to be appreciated that the overlapping ends of
adjacent members may be welded together, if desired. The use of
welding may be in addition to or in place of using fasteners.
[0025] The first end of the structural member may include an
abutment (or alignment) shoulder for abutment/alignment of the
structural member with an adjacent structural member. The abutment
shoulder may be provided on one or more of the ribs and/or
core.
[0026] The structural member may adopt any suitable form. For
example, the structural member may include 2, 3 or 4 (or more)
longitudinally extending ribs. Further, the core may, in one or
more forms, be at least partially hollow.
[0027] In one possible form, the profile of each rib tapers from
the outer edge to the core. The provision of a taper may provide
one way of maximizing the strength to weight ratio of the member,
thereby potentially reducing the bending and buckling of the member
under axial load. It is to be appreciated however, that each of the
ribs may adopt any suitable form, and need not taper. In one
alternative form, each rib (in profile) may taper outwardly from
the core to the outer edge. In another alternative form, the
thickness of each rib may be approximately constant between the
core and the outer edge.
[0028] The structural member may be of any suitable form, such as a
pile section, building column, strut, beam or portion thereof.
Indeed, the Applicant considers that the member may be particularly
suitable for use as a pile section, in place of a conventional
wooden, reinforced concrete or steel pile section.
[0029] The profile of each rib may be generally straight, curved,
bent or any other suitable profile.
[0030] The structural member may include a second connecting
arrangement provided at the second longitudinal end thereof for
connecting the second end to another adjacent structural
member.
[0031] One or more ribs may extend outwardly from a location
generally aligned with a central axis extending longitudinally
through the core. The applicant also contemplates embodiments in
which one or more ribs extend outwardly from the core from a
location(s) generally not aligned with a central axis extending
through the core. Non-limiting examples of both arrangements are
illustrated in the accompanying drawings and described in the
associated description of drawings.
[0032] The core, or at least a central portion thereof, may be
solid or hollow. As a further alternative, the core, or at least a
central portion thereof, may be solid along a longitudinal
portion(s) thereof and hollow along another longitudinal portion(s)
thereof.
[0033] It will be convenient to hereinafter describe preferred
embodiments of the invention with reference to the accompanying
drawings. The particularity of the drawings is to be understood as
not limiting the preceding broad description of the invention.
[0034] FIG. 1 is an end view of a structural member according to
one form of the present invention.
[0035] FIG. 2 is a perspective view of the end of the structural
member illustrated in FIG. 1.
[0036] FIG. 3 is a perspective view of the end of the structural
member illustrated in FIG. 2 and the end of another substantially
identical structural member.
[0037] FIG. 4 is an end view of a structural member according to
another form of the present invention.
[0038] FIG. 5 is an end view of the structural member illustrated
in FIG. 4 with one end nested with an end of another substantially
identical structural member.
[0039] FIG. 6 is a perspective view of one end of another
structural member according to the present invention.
[0040] FIG. 7 is a perspective view of one end of yet another
structural member according to the present invention.
[0041] FIG. 8 is a perspective view of the arrangement illustrated
in FIG. 7 when connected to another pile section according to the
present invention.
[0042] FIG. 9 is a perspective view of a structural member
according to another form of the present invention.
[0043] FIG. 10 is a perspective view of a structural member
according to yet another form of the present invention.
[0044] FIG. 11 is an end view of two nested structural members, one
member being generally of the form illustrated in FIG. 4 and the
other corresponding to a further form of the present invention.
[0045] FIG. 12 is an end view of two substantially identical nested
structural members according to another form of the present
invention.
[0046] FIG. 13 is an end view of two substantially identical nested
structural members according to another form of the present
invention.
[0047] FIG. 14 is an end view of two substantially identical nested
structural members according to another form of the present
invention.
[0048] FIG. 15 is a perspective view of two structural members
according to a further form of the present invention.
[0049] FIG. 16 is an end view of a structural member according to
another form of the present invention.
[0050] FIG. 17 is an end view of the structural member illustrated
in FIG. 16 nested with another substantially identical structural
member.
[0051] FIG. 18 is an end view of a structural member according to
another form of the present invention.
[0052] FIG. 19 is an end view of the structural member illustrated
in FIG. 18 nested with another substantially identical structural
member.
[0053] FIG. 20 is a perspective view of three structural members
according to further embodiments of the present invention.
[0054] Referring to FIGS. 1 to 3, there is provided a structural
member in the form of a steel pile section 20. The pile section 20
includes a longitudinally extending solid core 22 and three
longitudinally extending ribs 24, 26, 28. Each rib 24, 26, 28, in
profile, extends outwardly from the core 22 (in a generally radial
direction) to a respective outer rib edge 30, 32, 34. Further, in
profile, each rib tapers from the outer edge to the core.
[0055] The pile section 20 includes a receiving aperture in the
form of a slot 36 provided in a first end 38 of the pile section
20. The slot 36 is provided for receiving an end 40 of an adjacent
pile section 42 (see FIG. 3). The receiving slot allows the pile
sections 20, 42 to be quickly and easily aligned for connection to
one another. It can be appreciated that, when connected, pile
sections 20 and 40 share a substantially common longitudinally
extending axis, and that pile section 40 is rotated (within the
slot 36) slightly about the axis relative to pile section 20 to
facilitate connection of the two pile sections.
[0056] In this regard, the first end 38 of the pile section 20
includes a first connecting arrangement for connecting the first
end 38 to the end 40 of the adjacent pile section 42. The
connecting arrangement includes apertures 44 provided in each of
the ribs 24, 26, 28 for receiving a plurality of fasteners. The
fasteners may be in the form of screw threaded fasteners (for
example, bolts), rivets or the like.
[0057] The provision of slot 36 and the first connecting
arrangement is most advantageous because it allows for the ends of
the pile sections 20, 42 to be nested, so as to be connected by way
of a lap joint to provide a robust and durable connection.
[0058] The connection of pile sections 20, 42 is desirable, because
it allows for the manufacture of pile sections in standard lengths,
which can be subsequently connected end-to end to provide an
overall pile structure of desired length.
[0059] Although not illustrated, it is to be appreciated that the
overlapping ends 38, 40 of adjacent members 20, 42 may be welded
together, if desired. The use of welding may be in addition to or
in place of using fasteners.
[0060] Although not illustrated, the pile section 20 may include a
second connecting arrangement provided at the second longitudinal
end thereof for connecting the second end to another adjacent pile
section.
[0061] Another pile section 120 according to the present invention
is illustrated in FIG. 4 and is illustrated as nested with an
identical pile section 120a in FIG. 5. A notable difference between
the pile section 20 illustrated in FIGS. 1 to 3 and pile section
120 is the number of ribs and the profile of each rib. It is to be
appreciated that pile section 120 is manufactured from a pair of
angle sections 150, 152 that are permanently and rigidly secured
together by way of connectors welded (or otherwise secured) there
between. Pile section 120 includes four ribs 124, 126, 128, 130
with the profile of each rib 124, 126, 128, 130 being straight
rather than tapered. The pile section 120 includes a receiving
aperture in the form of a slit (not clearly visible) and a
connecting arrangement including apertures (not visible) in each of
the ribs 124, 126, 128, 130. It is to be appreciated that in this
embodiment the central portion of the core 122 is substantially
hollow, given that the pile section is manufactured from angle
sections 150, 152, the corners 154, 156 of which are illustrated as
being spaced slightly apart. The ribs 124, 126, 128, 130, in
cross-sectional view, need not be spaced evenly. Also ribs 124,
126, 128, 130 need not be of equal length when viewed in
cross-section. These same possibilities exist for other embodiments
illustrated and described in this application.
[0062] A further pile section 220 is illustrated in FIG. 6. Pile
section 220 includes four straight ribs 224, 226, 228, 230
extending outwardly from a solid core 222. The pile section 220 is
manufactured in one section, rather than from two angle sections as
with pile section 120.
[0063] Another pile section 320 according to the present invention
is illustrated in FIG. 7. The pile section 320 is similar to pile
section 120 illustrated in FIGS. 4 and 5, except that the first end
338 of pile section 320 can be seen to include an abutment shoulder
340 for alignment of the pile section 320 with an adjacent pile
section (not illustrated) prior to connection of the pile sections.
The abutment shoulder is welded to and extends across ribs 326 and
328. An identical shoulder (not visible) also extends across ribs
324 and 330. The pile section 320 has a substantially hollow
central core portion.
[0064] FIG. 8 illustrates pile section 320 (but upside down when
compared to FIG. 7) with one end connected to the end of another
pile section 420 by bolting the two pile sections 320, 420
together. It can be seen that the end of pile section 420 abuts the
shoulder 340 of pile section 320, which provides means of
transmitting compressive loads and facilitates the alignment and
connection process of the piles.
[0065] FIG. 9 illustrates another pile section 520 including a
cylindrical lug 550 provided on ribs 524, 526 to facilitate
alignment and connection of the pile section 520 to another pile
section (not illustrated).
[0066] FIG. 10 illustrates a pile section 620 formed from two angle
sections 650, 652, but with angle section 650 slightly longer in
order to potentially simplify alignment and connection of pile
section 620 to another pile section (not shown).
[0067] FIG. 11 illustrates two pile sections 720, 820 with their
ends nested together. It can be seen that the pile sections 720,
820 (or at least the ends thereof) have, in profile, ribs of
differing lengths.
[0068] FIG. 12 illustrates pile section 920 with one end nested
with an end of an identical pile section 920a. Pile section 920
includes four ribs 924, 926, 928, 930 including respective bends or
returned outer edges 924a, 926a, 928a, 930a. The outer edges 924a,
926a, 928a, 930a can provide added resistance to pile section
buckling. The outer edges 924a, 926a, 928a, 930a can be relatively
easily formed by pressing.
[0069] FIG. 13 illustrates pile section 1020 according to the
present invention with one end nested with the end of an identical
pile section 1020a. Nesting is possible in this embodiment once one
of the pile sections 1020/1020a is inverted (ie. turned upside
down). The pile section 1020 includes three ribs 1024, 1026, 1028
defining an overall Y-shaped profile. It is to be appreciated that
the ribs 1024, 1026, 1028 don't extend outwardly from the centre
point of the core 1022. Instead, each rib extends outwardly from
the core 1022 from a position slightly off-centre from the core
centre point. Ribs 1024, 1026, 1028 are not tapered.
[0070] FIG. 14 illustrates pile section 1120 with one end nested
with the end of an identical pile section 1120a. Pile section 1120
includes two curved ribs 1124, 1126 defining an overall S-shaped
profile.
[0071] FIG. 15 illustrates the ends of two pile sections 1220, 1320
(which may or may not be identical pile sections) when connected
together by way of a fillet weld 1250 along the lapped faces of
ribs 1224, 1226, 1324, 1326. It is to be appreciated that fasteners
have not been used to connect the pile sections 1220, 1320,
although fasteners could be used in conjunction with or in place of
the fillet weld 1250 if desired. A similar weld may be provided on
ribs 1228, 1230, and the remaining two ribs (not visible) of pile
section 1320, if required.
[0072] FIG. 16 illustrates a pile section 1420 including three
curved ribs 1424, 1426, 1428 extending outwardly from the solid
core 1422. FIG. 17 illustrates one end of pile section 1420 nested
with and connected to one end of an identical pile section 1420a by
way of fasteners 1450 extending through apertures 1444, 1444a
provided in ribs 1424, 1424a. Similar fasteners made be provided
through the other rib pairs, but have been omitted to simplify the
drawing.
[0073] FIG. 18 illustrates a pile section 1520 including three ribs
1524, 1526, 1528 having respective bent or returned outer edges
1524a, 1526a, 1528a. Each rib 1524, 1526, 1528 extends outwardly
from the solid core 1522 slightly off-centre from the central axis
X of the core 1522. FIG. 19 illustrates one end of pile section
1520 nested with an end of an identical pile section 1520a. Nesting
is possible in this embodiment once one of the pile sections
1520/1520a is inverted (ie. turned upside down).
[0074] FIG. 20 illustrates one possible arrangement of three pile
sections 1620, 1720, 1820 connected to one another to create a
pile. It is to be appreciated the pile section 1620 is the
lowermost pile section and so may be subjected to the greatest
load. Consequently, pile section 1620 is the larger pile section,
thereby providing it with the greatest strength of the three pile
sections. In other situations, the larger section may be used for
the uppermost or middle sections, so as to provide greater
resistance to buckling.
[0075] Although not clearly shown, pile sections 1720, 1820 may be
substantially identical. Pile section 1620 is manufactured from a
pair of angle sections 1650, 1652, and includes ribs 1624, 1626,
1628, 1630, a substantially open core 1622 and at least one (and
possibly two) abutment shoulder 1640. The shoulder 1640 illustrated
is welded to ribs 1624, 1630. The lower end of pile section 1620
could be driven into the ground to the required depth. Pile
sections 1720, 1820 are used to provide an overall pile structure
of the required height.
[0076] Pile section 1720 can be relatively quickly and easily
connected to pile section 1620 when the pile sections are
orientated vertically, by inserting the lower end of pile section
1720 into a receiving aperture in the form of a slot or slit (not
visible) in the upper end of pile section 1620. The pile section
1720 is lowered in a downwards direction until it abuts the
shoulder 1640, at which time fasteners are inserted through aligned
holes provided in the ribs of pile sections 1620, 1720 to securely
connect the two pile sections 1620, 1720 together.
[0077] As similar process is then used to connect the lower end of
pile section 1820 to the upper end of the pile section 1720.
[0078] More or less pile sections could be connected together in
place of the three pile sections 1620, 1720, 1820 illustrated in
order to provide an overall pile of a desired height. It is to be
appreciated that the specific height of each of the pile sections
1620, 1720 and 1820 may be selected as desired. Also, it is to be
appreciated that the profile and type of each pile section may
differ from those illustrated in FIG. 20. Any one or more of the
pile section designs illustrated in FIGS. 1 to 19 may also be used,
or any other suitable pile section shape in accordance with the
present invention but not specifically illustrated may be used.
[0079] The connections between pile sections 1620, 1720 and 1720,
1820 are inherently strong. Axial forces are transmitted directly
by the abutting surfaces between pile sections, augmented by bolts
(and/or welds--not shown). Bending capacity is inherently high
because the members overlap. Hence the joint is stronger in both
bending and compression than the basic members. It is to be noted
that the connections allow for the core of each pile section to be
in line, rather than a less desirable arrangement whereby the cores
are not in line.
[0080] The term `core` as used in this specification is to be
interpreted broadly, especially with regard to one or more of the
embodiments of the invention as described, defined and illustrated,
where a separately identifiable core may not be clearly
visible.
[0081] The pile sections according to the present invention can
also be relatively easily pointed (or otherwise shaped) at one or
both ends by trimming the corners of the ribs. This enables
accurate location at the start of the piling process and minimises
damage to the pile section end from underground obstructions.
[0082] The pile sections of the present invention can potentially
eliminate at least some of the time, effort and cost associated
with geotechnical investigation and predictions potentially need
not be so thorough. Project costs can be potentially further
reduced because contingency allowances, normally made by
contractors in their tenders to cover the cost of extra length of
conventional pile sections, can be reduced.
[0083] Compared to existing steel structural members such as
H-shaped profile pile sections, the X-shaped profile design of the
present invention (and possibly also other profile shapes according
to the present invention) provide improved axial load. This is
potentially at least in part because the X-shaped profile has a
reasonably uniform stiffness the entire way around the profile and
hence has no identifiable plane of buckling. This is a very
desirable characteristic for piles, pile sections, columns, struts
and other structural members.
[0084] X-shaped profile pile sections according to the present
invention can be manufactured from standard hot-rolled steel
angles, which are inherently more cost effective to manufacture
than the more complex H-shaped pile sections currently used.
Additionally, instead of hot rolled steel, the angles used to
fabricate the X-shaped profiles can be cold pressed from steel
plate, which also minimizes the cost of production.
[0085] The present invention thus potentially obviates the high
investment cost associated with rolling mills, as at least the
X-shaped profile can be relatively easily manufactured from stock
angle sections in ordinary workshops using straightforward
techniques, using simple jigs to provide manufacturing
accuracy.
[0086] Joining (or splicing) of pile sections according to the
present invention is also a relatively straightforward process when
compared to that required for existing pile sections. Pile sections
according to the present intention are inherently self-aligning so
that another pile section simply slots into place and is
immediately self-supporting. Then it can be simply a matter of
inserting and tightening the bolts to provide a sound, secure
lapped joint connection, considered generally stronger than the
parent material.
[0087] It should be appreciated that pile sections according to the
present invention would typically (but not essentially) include a
substantially identical slot, slit or other suitable aperture and
associated connecting arrangement at each end of the pile section,
allowing either end of the pile section to be connected to the end
of an adjacent pile section or, as illustrated in FIG. 20, each end
of the pile section to be connected to a respective adjacent pile
section.
[0088] Unlike existing pile sections, there is no need for a pile
comprising two or more pile sections according to the present
invention to have a constant profile along the entire length of the
pile. Instead, it may be that the lowermost pile section is larger
because that is where the load capacity on the assembly is likely
to be greatest. The remaining (upper) pile sections of the
structure may have a smaller profile, thereby reducing the total
mass of the assembled pile by up to 25% (or more). Alternatively,
the uppermost or middle portions may be larger so as to provide
greater resistance to buckling. The reduced mass provides a way of
reducing the overall cost of pile. This is possible, because the
present invention allows different pile section thicknesses and
sizes to be connected together relatively easily.
[0089] Pile sections driven through fill can experience additional
loading due to down-drag arising from settlement of the fill. With
the smaller upper section as described above this effect may be
reduced.
[0090] Overhead restrictions such as power lines, trees, or inside
buildings can sometimes cause problems for pile driving. Short pile
sections and a small driving rig is often the only practical
solution, with the latter connection of pile sections to create an
overall pile being necessary. The present invention provides a
means of relatively quickly and easily connecting (or splicing)
pile sections together.
[0091] The ease of connecting pile sections together according to
the present invention results in pile section off-cuts being
relatively easily re-used, possibly for use in a neighboring pile
assembly. Thus, off-cut wastage can be significantly reduced when
compared to existing pile arrangements. This has a further benefit,
in that there is a potentially greatly reduced need for off-cuts to
be removed from the construction site. Further, piling contractors
are potentially far less likely to err on the high side when
selecting lengths of pile section, which is currently a common
practice that can typically result in 10 to 20% pile wastage.
Another advantage is that choice of length is not critical which
means steel mills, merchants, and piling contractors do not need to
produce or stock a large range of length increments, thereby
reducing inventory costs.
[0092] A comparison of a pile having an X-shaped profile according
to the present invention can be made with a conventional H-shaped
pile having similarly sized profile dimensions and a similar linear
mass, such as provided below.
TABLE-US-00001 H-Pile X-Pile Pile Size 310UBP79* 2/200 .times. 200
MS Angles Length 12 m 12 m Flange Thickness 11.1 mm 13 mm
Mass/metre 78.8 kg/m 80 kg/m Total weight 957.6 kg 960 kg
Cross-sectional area 10,000 mm.sup.2 10,180 mm.sup.2 2.sup.nd
Moment of Area Ixx 52.9 .times. 10.sup.6 mm.sup.4 -- Iyy 164
.times. 10.sup.6 mm.sup.6 -- Iuu -- 62.4 .times. 10.sup.6 mm.sup.4
Ivv -- 75.9 .times. 10.sup.6 mm.sup.4 Effective perimeter 1200 mm
1160 mm *The largest of the standard H-shaped steel profiles
designated for use as piles in Australia and elsewhere.
[0093] The X-shaped profile is considered by the applicant to be
inherently superior. This is because the stiffness of the X-shaped
profile is fairly uniform in all directions, whereas the H-shaped
pile is significantly weaker about one of its two profile axes.
[0094] The pile having an X-shaped profile is also less susceptible
to local damage than a conventional pile having an H-shaped
profile, as the X-shaped pile ribs are thicker. Sturdy edges ensure
greater resistance to damage during transport and handling and,
more importantly, when striking boulders or other buried objects
during the pile driving process. Another advantage of the thicker
ribs is corrosion resistance, ie. thick ribs suffer comparatively
less weakening for a given amount of metal loss due to corrosion
than thin ribs.
[0095] The applicant also considers that piles and pile sections
having an X-shaped profile will be cheaper to produce than
conventional steel piles and pile sections having an H-shaped
profile. Ease and low cost of joining steel pile sections means
that pile driving contractors no longer need to seek to maximize
pile lengths. Accordingly, smaller pile driving rigs can be used,
thereby saving capital outlay, and lower transport and setting up
costs.
[0096] One or more of the above referred advantages of piles/pile
sections having an X-shaped profile may also be inherent in the
other profile shapes of the piles/pile sections and other
structural members discussed, illustrated and contemplated in the
present application.
[0097] Again, it is to be appreciated that the structural member of
the present invention may be of any suitable form, including a pile
section, pile, building column, strut, beam or portion thereof.
[0098] Finally, it is to be understood that various alterations,
modifications and/or additions may be introduced into the
construction and arrangement of the parts previously described
without departing from the spirit or ambit of this invention.
* * * * *