Static structures (e.g. – buildings) – Footing or foundation type
Reexamination Certificate
2000-09-19
2002-11-05
Friedman, Carl D. (Department: 3635)
Static structures (e.g., buildings)
Footing or foundation type
C052S167400, C052S167900, C052S298000, C405S229000, C405S255000
Reexamination Certificate
active
06474030
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a pile foundation structure for supporting a footing serving as a foundation of a large-scaled and heavy upper structure such as a high building, and propagating a load of the upper structure to the underground depths by means of plural point bearing piles or friction piles disposed within a construction range of the upper structure so as to be spaced from each other, and driven into the undergrounds such as a solid rock.
BACKGROUND ART
Such a pile foundation structure is conventionally known, such as the structure illustrated in
FIGS. 11 and 12
. In other words, it has a structure wherein plural point piles or friction piles
100
(hereinafter called piles) disposed within a construction range (shown by the outline thereof) of an upper structure A so as to be spaced from each other, is driven into the underground B, such as solid rock, and a head of the each pile
100
i.e., a pile head is buried into a foundation
101
(hereinafter called a footing) on a side of the upper structure A, whereby the pile
100
is rigidly joined to the footing
101
.
FIG. 13
illustrates in detail a joint structure between each pile
100
as a structure element and the footing
101
. A lower end ofthe footing
101
is mounted on a head of the pile
100
, and the pile
100
is rigidly jointed to the footing
101
by reinforcing steel members
102
including a pile reinforcement and a concrete-reinforcing bar, and concrete.
As mentioned above, the conventional pile foundation structure is constructed so that each pile foundation has the pile
100
rigidly joined to the footing
101
so that it is longitudinally and laterally disposed within the construction range ofthe upper structure A, so as to be appropriately spaced from each other. In case of the conventional pile foundation structure, earthquake motion which is propagated from the underground B when an earthquake happens, is input to the upper structure A via a rigid joint portion between the head ofthe pile
100
and the footing
101
. In this moment, it is not only that a stress such as a shear force is concentrated on the joint portion of the head of each pile as a boundary portion between both of them, but also that, even if joint between heads of the piles
100
and the footing
101
is perfect, a great bending moment happens on the pile
100
in the underground B. As a result, the joint portion between the pile head and the footing
101
, and the pile
100
are easily damaged and destroyed. Thus, it is extremely difficult and requires a long period and huge costs to conduct a restoration construction in case that damage or destruction is caused on the pile
100
, and the joint portion between the pile head and the footing
101
.
In order to resolve the above problems, the pile foundation structure employing a sliding structure is suggested in a gazette of published Japanese Patent Application Laying-Open No. 1-102124.
In other words, the pile foundation structure shown in
FIG. 14
is structurally described below. A number of steel reinforcement members
103
annularly disposed on an upper end of the pile
100
, and steel pipes
104
disposed so as to surround the steel reinforcement members
103
in a state of allowing lateral movement of the steel reinforcement members
103
are upwardly extended. At each lower end portion of the steel pipes
104
, annular engagement projections
105
are arranged so as to be connected to an upper end portion of the pile
100
in a buried state. Moreover, a top board
106
is welded to the upper end portion of the steel pipes
104
, the top board
106
is provided with flexible holes
107
for making the steel reinforcement members
103
pierce the top board
106
so as to respectively allow lateral shaking of the steel reinforcement members
103
. The steel reinforcement members
103
protruding above the top board
106
through the flexible holes
107
, are connected to the footing
101
of the upper portion thereof. Furthermore, there is a sliding member
109
between the top board
106
and a footing metal member
108
, through which the footing
101
is slidably mounted on the top board
106
.
In the pile foundation structure having such a sliding arrangement, when the earthquake motion is applied, the steel reinforcement members
103
are bent, and at the moment while they are bent, the sliding member
109
makes the footing
101
slidingly move with respect to the pile
100
, thereby making it possible to restrict stress concentration on the joint portion of the pile head. However, the sliding amount is regulated by the size of each flexible hole
107
disposed on the top board
106
, and the pile
100
is connected to the footing
101
by the steel reinforcement members
103
whereby the shearing force and the bending moment cannot be efficiently absorbed in case of applying the excess earthquake motion. Consequently, it is unavoidable that the joint portion between the head ofthe pile
100
and the footing
101
is damaged or destroyed. In the same way as the conventional pile foundation structure in
FIG. 13
, there has been a problem wherein earthquake-proof property and earthquake avoidable property cannot be ensured enough.
SUMMARY OF THE INVENTION
The present invention has been conducted in view of the above mentioned circumstances, i.e., the background of the prior art. Objects of the present invention are to provide a pile foundation structure which can reduce stress concentration applied to a joint portion of a pile head and a bending moment applied to the pile which are accompanied with earthquake motion; make a whole of a structure lightweight; reduce costs; prevent the pile and the joint portion of the pile head from being damaged or destroyed; and also enhance excellent positional restoration performance of an upper structure after the earthquake happens.
A first aspect of the invention relates to a pile foundation structure for joining a footing of an upper structure to heads of plural piles (or pile heads) disposed within a construction range of the upper structure so as to be spaced from each other, and driven into the underground, characterized in that
a roller bearing structure is constructed as each joint structure between some of the plural piles and portions of the footing of the upper structure corresponding thereto, wherein
a protrusive-supporting-portion having a flat top surface is disposed on a side of the pile head, in a state of protruding above an upper surface of the underground,
a recessed-joint-portion having a flat top surface is disposed on a side of the footing of the upper structure, so as to correspond to the protrusive-supporting-portion and be greater than the protrusive-supporting-portion, and
a sliding member is interposed between the top surfaces of the protrusive-supporting-portion and the recessed-jointing-portion,
thereby making it possible to relatively slidingly move a joint portion of the head of the pile in a horizontal direction; and
a pin bearing structure is constructed as each joint structure between the others of the plural piles and portions of the footing of the upper structure corresponding thereto, wherein
a spherical-supporting-portion having a convex or concave outer surface is disposed on a side of the pile head, in a state of protruding above the upper surface of the underground,
a spherical-joint-portion having a concave or convex inner surface is disposed on a side of the footing of the upper structure, so as to correspond to the spherical-supporting-portion and be greater than the spherical-supporting-portion, and
a sliding member is interposed between the outer surface of the spherical-supporting-portion and the inner surface of the spherical-joint-portion of the footing of the upper structure,
thereby making it possible to relatively slidingly rotate the joint portion of the head of the pile.
According to the first aspect of the present invention having such an arrangement, the earthquake motion which is propagated from the underground when the earthquake happens, is input to
Friedman Carl D.
Glessner Brian E.
Jones Tullar & Cooper P.C.
Nippon Pillar Packing Co. Ltd.
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