Crossing References of The Inventors

Other References

[1] Hao, S., Report of NCHRP(National Cooperation Highway Research Program)188

[2] Federal Emergency Management Agency (FEMA), Reports 350-353, 2000. [3] USGS Records: www.usgs.gov

[4] California Department of Transportation (Caltrans), "The Continuing Challenge: The

Northridge Earthquake of January 17, 1994".

[5] Federal Highway Administration(FHWA): Post- Tensioning Tendon Installation and Grouting

Manual, 2013

[6] ASCE/SEI, "Minimum Design Loads for Buildings and Other Structures", 1995-2016 versions.

[7] "LRFD Bridge Design Specifications", AASHTO, the 1 ^st (1994) to the 7 ^th Editions (2016)

[8] AASHTO "Guide Specifications for Seismic Bridges' Design",, 1 ^st Ed., Second Edition, 2011

[9] Amendment to AASHTO LRFD Bridge Design Specification-4 ^th Ed., Section 14: Joints and

Bearings, Caltran, 2010.

[10] Post-Tension Institute (PTI) Publication: "Anchorage Zone Design," Post-Tensioning Institute,

First Edition, October, 2000.

[11] Post-Tension Institute (PTI) Publication: "Post-Tensioning Manual," Sixth Edition, 2006.

[12] American Segmental Bridge Institute (ASBI) Publication: "Construction Practices Handbook for Concrete Segmental and Cable-Supported Bridge" Third Edition, 2019.

[13] Touaillon J., "Improvement in Buildings", United States Patents Office, Letters Patent No.

99.973, February 15, 1870.

[14] "Experimental Investigation on the Seismic Response of Bridge Bearings", Univ. of California,

Berkeley, EERC-2008-02, 2008.

[15] Kelly, J. M., 1997, "Earthquake-resistant design with rubber", 2nd Ed., Springer, London. [16] "Rotation Limits for Elastomeric Bearings", Report 12-68, University of Washington, 2006

[17] Hao, S., "Retrofit/Replacement for Free Bridge Road over Running Reelfoot Bayon and

Discussion of the SVC Application of STD6-1 Seismic Detailing for SDC D Bridge", Presentation at the Structural Division, Tennessee Department of Transportation, US, Sept. 5, 2019

[18] Hao, S., "V-connection against Bridge's Deck Overturn", Presentation at the Chinese National

Bridge Annual Conference, Nov. 15 ^th , 2019

[19] Hao, S., "V-connector to Protect Bridges from Earthquake Damage and Deck's Overturn",

Presentation at the Chinese Bridge Magazine Annual Road Showing: Dec. 7 ^th , 2019

Description

Field of Invention

This invention discloses a class of design detailing of the parts and connecting methods for the construction of large-scaled civil engineering structures such as bridges and buildings that are mainly made of concrete components or combination of concrete and steel members. Concrete, as a practical construction material, is characterized by high capacity against compression but is lack of tension strength. A common method to reduce tension stress in a flexure concrete member, e.g. a beam or a column, is the “post-tension” technique that uses tendons or rods to impose compressive force at such a component’s two ends before it comes to service, which will keeps its concrete matrix under compressive condition that trades off the tension stress caused by actual applying loads during service, see Fig. 1. Obviously, the conventional post-tension method in this figure is effective only for a member with the geometry that at one direction the size is considerable larger than that other two orthogonal directions, for example, a flexure member, by which tension stress peak presents along length direction when it is under external load-induced bending moment. However, it remains as a challenge for construction industry how to apply post- tension when plural flexure members meet at a crossing joint along one, two, or three- ways; Fig. 2(a) is such an example of the joint of beams and one column in a bridge, whereas Fig. 2(b) is the example of a three-ways crossing-joint in a building. On the other hand, for horizontally aligned structure components, for example, precast segmental bridge’s blocks, structures’ weight essentially transfers to the shear force on contacted surface-pair between two connected segments. To sustain this kind of shears, grouting by epoxy or dry-joint with additional concrete shear keys are the two common methods.

However, grouting is a time-consuming process that may trade off the advantage of accelerated construction by precast segmental members, whereas by concrete shear key the capacity against shear is limited while it remains as another challenge to assure shear keys fitted-well on contact surface-pairs.

Generally speaking, strength of crossing joints is crucial to a large-scaled civil- engineering construction, in the perspectives of structural integrity and safety. This is because, obviously, fail of such a joint will results in the failures of all connected members.

As stress-level at a crossing-joints is generally higher than other parts, therefore, the robustness and strength at these kinds of locations essentially determines a structure’s load capacity, especially under extreme load conditions such as hurricane, strong earthquakes, collision between bridge and barges or vehicles, and explosions. Another common engineering way of construction without posttension is the method termed “cast-in-place”(CIP), i.e. to prearrange rebar network inside pre-made formwork for a structure; then cast in liquified concrete mixes, utilizing the rebar network embedded in concrete matrix to resist tension and shear. However, by this process the solidification and necessary aging of cast-in concrete need at least 28 days; to build a formwork for cast-in costs about 20% to 60% extra budget of a construction.

By contrast, when a structure’s major members can be made in factory, i.e., manufacturing , precast, and post-tensioned of beams and columns off-site, then assembling these components on-site, which will significantly reduce construction process and bring up remarkable economic benefit but, nevertheless, by this kind of modular construction it will highlight the determinant role of the joints that connect these prefabricate members for load capacity and robustness of such a structure built. To this end, the present invention discloses a class of methods with innovative design detailing for strengthening crossing-joints of structural components and increasing load-capacity along the direction perpendicular to posttension while enabling modular construction.

Background of the Invention

A long-existing challenge to the civil engineering community is how to achieve fast construction while ensuring a structure’s integrity and sustainability. In a densely populated area, building a bridge may take a long time, often causing traffic congestion that results in not only inconvenience to the motoring public but also economic losses due to unproductive time lost in traffic delays. On the other hand, the devastations disasters, such as the earthquakes in past several decades, remind us of the continuing threat from nature to human-being’s life, particularly, for the regions with high seismic risk in United States and those in the world. Needless to say: technologies and methods for accelerating construction are certainly desirable or necessary but only if structural integrity and robustness of the structure are assured for public safety. The present invention is an effort towards this goal.

The majority of large-scaled civil engineering constructions is built by structural concrete or combined concrete-steel composites. To avoid the drawback of lacking tension strength for concrete, posttension to prestress compression is a common technique widely applied. However, as explained previously, this technique is generally available for slim members like beams and columns. Crossing-joints of concrete constructions are often under complicated stress state and can be the weakest-link for such a structure. An extreme case is the collapse of the tragic collapse of the pedestrian bridge at the Florida International

University campus in March 2018. This, nevertheless, seems yet to be the focus with broad interesting so far, as reviewed in the following section “Prior Arts”. This art presents a class of engineering solutions to reinforce connections between structural members, especially the crossing-joint of concrete members or a combination of concrete and steel members by posttension, so as to achieve improved seismic resistance and capability for modular construction.

Prior Arts

A large-scaled concrete or steel-concrete composite structures, i.e. bridges and buildings, basically comprises four kinds of major structural components: horizontal flexure members like beam and roof-shell, vertical flexure members like column, foundation components such as footing, and crossing-joints to connect these components.

Prestress for a flexure member like that in Fig. 1 belongs to common engineering practices nowadays. Continuing efforts and associated inventions can be seen for the post-tension of assembled column blocks and footing.

At 1953 the patent US2645090 introduces a method that one-piece or sectional concrete pile is cast with a central bore extending longitudinally, where a prestressing cable passes through with the fittings swaged at two ends, so the cable is under tension and the pile is in compression, Fig. 3(a). This concept has been extended in US3899891 where a pile is an assembly of a plurality of vertically arranged, tubular driving shell sections joined one by one with a through prestressing tendon; the taped anchor technique introduce in

US3703748, Fig.3(b). By contrast, the invention using steel socket at footing to anchor a rod and a nut to fasten the rod at pile top is disclosed in US 1647925, Fig. 4(a). Chinese application CN110685215A introduces an assembly of multiple pile-segments and footing with through rebar-segments; steel sleeves are engaged to connect the rebars in adjacent pile-segments just above their contact surface-pair, Fig.4(b). Similar to the embodiment in

Fig. 4(b), tendon goes through pile-segments with added sockets at the contact surfaces and posttensioning at top is presented in CN109610304A, Fig. 4(c). Regarding the technique detailing of coupler to connect cables and rebars, US 6560939B2 introduces an intermediate anchorage system that connect to two tendon’s ends not aligned on the same axis Fig. 5(a). A detailing of threadable coupler for two rods with threaded ends is presented in PCT/KR2006/004958, Fig. 5(b). Structural assembly has been introduced in

US6742211 where a pile block with concave bottom surface is dropped on another pile block with convex upper surface to increase the resistance against lateral shift, Fig. 6. Each pile block has a cylinder opening on its convex upper surface and passing-through bom, filled with concrete grout surrounding a passing-through tendon. Fig. 7 presents a wet joint between two bridge’s spans and one pier in US3794433, which did have brought a revolutionary progression for concrete bridge’s construction with posttension. Fig. 8 is a crossing-joint of two posttension conduits with saddle anchorages in US2950517 at 1960, which is a part for a crossing arranged tendon network in a plane embedded in highway’s deck. JP2011001717A engages side-bolts set, termed “temporary cradle”, to position a pillar onto a two-way slab crossing-joint for connecting the threaded rebars projected out from the bottom of the pillar and the threaded rebars projected out from the surface of the slab’s crossing-joint by “couplers”; then make a formwork containing these couplers for casting concrete, Fig. 9. Though the pillar is precast and can be prestressed, no post-tension has been imposed onto the joint during the operation.

While the general guide-line of the post-tension has been provided in [5] for concrete bridges, a method to prestress a wet joint between two spans on a pier’s top for seismic resistance has been a common procedure of daily engineering practices by

Tennessee State Department of Transportation (TDOT), United States, for decades. The corresponding procedure is as follows: a bolt was first been cast into a column and projected out at its top; then two spans’ ends were dropped on the top at the two sides of the bolt; then concrete-mix was cast into the gap between the two spans’ ends while the bolt’s top is fastened to impose compression on a part of this wet joint. Fig. 10(a) and (b) are two standard design drawings that give two kinds of bearing pads for the wet crossing joints’ detailing to provide certain capability of lateral sliding. In the first an elastomeric pad is set between the bottom of the joint and the pier’s top, whereas a bituminous fiberboard is laid as bearing pad. However, this class of design does not consider the capacity of the anchor bolt’s shear strength when lateral sliding occurs. Fig. 10(c) is an example of the rebar network layout within the wet-joint.

A prior art with top fastening is JP200 8050820A for two structural blocks vertically connected by a through bolt, Fig. 11 ; where the bolt’s lower end is anchored into the lower block while its upper end is fastened onto the upper block’s top. Instead of elastomeric or bituminous fiberboard in Fig. 10, a V-shaped contact surface between the two blocks is designed that allows relatively horizontal-sliding; to accommodate this kind of motions, the hole’s diameter for passing-through the rod in upper block is much larger than that of the rod; a thick buffer washer has been set between the nut and the top surface of the upper block.

As explained in Fig. 1, post-tension provides compression force by the tendon along the longitudinal direction, whereby a practical question is how to improve such a structure’s capability to against the shear along the plane crossing to the direction of post- tension. Taking bridge’s pier as an example, extreme load conditions such as earthquakes, hurricanes, vehicles collisions, and explosions, are generally characterized by extreme high lateral forces. The rod-fastening crossing-joints designs in both Figs. 10 and 11 imply the consideration allowing relatively-lateral sliding to reduce lateral inertia force when the bridge is struck by strong earthquake, but the design detailings in both do provide sufficient consideration to sustain such a motion and, thus, the lateral force will shear out the rod or bolt fixed at the location, as depicted by the plot on left in Fig. 11. Vertical extreme loads will also introduce extreme high combined tension and shear on post-tension tendons or rods; these kinds of loads occur when tsunami strikes bridges, or for the bridges in the near- site to an earthquake’s epicenter, or when overweight vehicle along one-side of a bridge’s deck.

To reduce the shear stress concentration on a pin when connected structures struck by earthquake, the prior art PCT/US2016/013741 introduced a combination of pin and V- shaped crater to connect a bridge’s pile to beam, which leads to increasing capacity against lateral shear, Fig. 12. To smear out the high shear stress concentration around a contact surface-pair between two connected structural components, an additional embodiment is design of the pin with locally enlarged diameter or employing additional shear reinforcement-ring, Fig. 13. Nevertheless, the detailing in Fig. 12 was designed for fastening superstructure against lift-up, instead of post-tension. The detailing of the anchor’s design in Fig. 12 is also too sophisticated. As a continuing innovation based on the concept of V-connectors, the embodiments of fix-end pin and hinge-end pin have been introduced in the prior art PCT/US2018/013205, see Fig. 14.

Regarding seismic isolation, Fig. 15 is the prior art (US6021992), termed friction pendulum sliding bearing (FPS), for structures’ seismic protection. It belongs to a group of prior arts that includes dozen of US patents and tens in other countries, based on the principal of the pendulum depicted on the right-hand side of the figure to use carried superstructure’s weight-induced lateral force-resultant on arc surface to resist horizontal inertia caused by ground motion. By contrast, the prior art PCT/US2012/063127 disclosed the invention to utilizing the horizontal resultant of carried superstructure’s weight on V- shaped sliding surface to resist earthquake-induced lateral motion. Whereby the enhanced novel designs of horizontal sliding-pin and vertical reinforce-pins (termed fastener in the art), respectively, are compatible to the V-geometry guided horizontal displacement to reduce inertia while to confine the vertical separation between the super and substructure connected, Fig. 16.

The present art can be considered as a partially continuation of the innovations in these prior PCTs but with additional feature of post-tension.

Summary of the invention

As reviewed in the previous section, conventional construction methods utilizes posttension to prestress compression along one direction in a structural member to trade off tension stress peak caused by service loads, which, nevertheless, does not always provide sufficient capacity to resist forces and resulted distortion along other directions nor improve unfavorited stress state at the locations with complicated geometries when peak stresses are not parallel to the direction of posttension, for example, crossing-joint between multiple concrete members. Extreme load condition, such as strong earthquake, causes horizontal forces and corresponding structural distortion that can be perpendicular to the direction of posttension to columns as well as that for segmental bridge decks. To solve these engineering issues, the objects of this invention are summarized as follows:

(a) A class of novel design detailing and associated innovative devices for establishing and reinforcing structural connections that enables post-tensioning along multiple directions, particularly, for the crossing-joints to connect concrete members or a combination of concrete and steel members.

(b) This disclosed invention is aiming on the following respects: (i) increased capacity to sustain strong impacts along direction different from the directions treated by conventional methods; (ii) capability to restore original configuration after temporal distortion occurs due to extreme external impacts; (iii) convenient for structure’s erection and assisting members’ positioning for junction; (iv) enabling modular construction; (v) simplicity and economy.

In the following statements and texts, “a unit” refers to “a block” or “a component” or “a member” that takes major force-flow in a civil engineering construction such as a span- beam or a column in a bridge or a building; whereas design detailing refers to all involved parts and components in the associated device, or apparatus, to fulfill the objects listed above, where the parts and components may include aforementioned unit. However, thereinafter a “part” refers to a part or a component of the apparatus.

According to engineering convention, a “wet joinf’ refers to a crossing joint made by on-site cast-in concrete to join flexural structural members such as beams and one column at where they met; whereas a “dry joinf’ is a precast joint-block which is dropped into designated location to join the members to be connected. As reviewed in the previously section, very few technique has been disclosed due to the difficulty for positioning.

Connecting two units can be managed by pulling one end of an inserted bar that is with other end fixed onto one unit, so as to impose compression on contacted surface-pair between the units; for example, the beam in Fig.1 can be two short beams end to end tied together by the posttension, whereby the robustness of the connection relies on the friction on the contacted surfaces. Though higher compression may introduce elevated friction on the contacted surfaces, this elevation is confined by the strength limit of the bar for posttension. When extreme high load, for example, earthquake, hits the structure that results in the force perpendicular to posttension, tiny relative sliding of the contact surface- pair causes high shear stress concentration at the interface, as depicted in the left-most plot in Fig, 13; combined stress peak of this shear and posttension in a bar may cut the bar immediately.

Therefore, the central ideas under the embodiments to be disclosed are to reduce this shear stress concentration, to reinforce the bar locally, and to utilize intrinsic structural properties, such as weight and original designed posttension, to fulfill these two assignments without changing global structure, which is also able to improve stress states at crossing-joints with posttensions along multiple directions.

Three basic conceptual drawings are given in Fig.17 focusing on reduction of shear concentration, which adopt the example of construction of a wet-joint for span over a pier in a bridge with posttension by the pin along vertical direction, proposed by this inventor; whereby the key embodiment is the combination of a V-shaped crater 3 with pin 1 or pin

2, where various methods to anchor the pins to the pier are introduced. The V-shaped crater, termed V-crater thereinafter, is a conical cavity with an opening on the contact surface between the pier’s top and the wet joint’s bottom, where opening’s diameter, depth, and curvature of a V-crater are designed according to preferred functions to be disclosed. The underlying innovative mechanisms for these embodiments are explained as follows:

When an extreme strong earthquake hits the structure in Fig. 17, the relative sliding between the wet joint and the pier is allowed because (i) to prevent sliding from strikes of future strong earthquakes needs very strong pin or tendon and changes in design as well that may result in unfeasible for engineering application; (ii) confined sliding has the effect of seismic isolation. Therefore, the V-crater is actually a buffer space for the pin’s bending under this kind of load conditions, so as to avoid it to be sheared out immediately. The curvature of the crater’s V-geometry is designed to match the pin’s bending configuration to introduce an asymptotical contact between the pin to the crater’s surface when lateral load Q applies, see Fig. 18(a), where the curved outline of the

V-shaped crater, denoted by the function Y(x) in the plot, can be estimated by the following analytical form: where x, L are the coordinate and the spanned length of the pin in a crater, i.e. the depth of the crater; I is the pin’s moment of inertia and E is Young’s elastic module for the pin’s material; k ₁ and k ₂ are the coefficients with the values between unit and two.

The asymptotical contact further introduces an uplift motion for the upper block when it moves laterally and the lateral displacement reaches a designed limitation.

This mechanism of engaging connected block’s weight to resist the lateral motion can be explained by Figs. 18(b), where, after the crater’s side is touched by the deformed pin, the corresponding lateral force Q can be divided to a resultant force normal to the curved pin’s surface and the resultant force tangential to the surface. The latter, , introduces the uplift motion of the upper block, which brings in its weight as an reactant against the lateral motion and confines the relative sliding within designated allowance.

According to Fig. 18(b) one sees that the amplitude of the tangential force N is determined by the angle a: where, according to the plot in Fig. 18(b) and (eq.1): where the symbol refers to the case that the maximum value of the function f(x) in the blanket over x coordinate is taken .

In actual engineering applications, earthquakes bring up significant high horizontal force Q to a structure [6-9], According to displacement-based seismic resistance design, a temporal sliding between a pair of connected major structural units, for examples, that in Fig. 2, will be beneficial to keep structural integrity because of the seismic effect mentioned previously. In details, the temporal sliding motion will result in (i) dissipation of vibration energy; (ii) reduction of structural stiffness that lowers corresponding inertia force; (iii) shift of the structure’s natural frequencies to avoid resonance.

However, the equ.1 is only for a cantilever beam with fixed length L. A pin inside a crater like these in Fig. 17 may deform in three different ways: (i) when the opening of the crater is too narrow, the pin will contact the edge of the opening first and the shear stress on this pin is similar to the case depicted on the left in Fig.

13; (ii) when the crater’s outline matches the curve predicted by eq.l at a load Q _I accurately, the pin’s body will contact to the crater’s surface completely in a sudden way when the lateral force Q reaches the value of Q _I ; when Q continues to grow, highly localized shear force may occur; (iii) the pin contacts the V- crater asymptotically when Q increases, in other word, the contacted area between the crater and the pin increases gradually, the pin deforms still like a cantilever but with gradually reduced span-length where x increases, that results in elevated resistance against further bending, as described by the model in Fig. 18(c). This mechanism provides better performance and thus is adopted for the disclosed design detailing. To find a solution of such a curve for the asymptotic contact, denoted as f(x) for the V-shaped crater’s outline, in [1] the following first ordinary differential equation has been derived based on the model in Fig. 18(c) satisfaction of the following two penalties assure the pin staying in elastic condition: where λ(x) is the radius of the pin that may vary and I(λ(χ)) is the pin’s sectional bending moment; F(Q,L/2 — x, λ(x)) is the pin’s end deflection as a cantilever under the load Q but with gradually reduced length L/2-x; E, σ _γ , τ _γ are the pin’s Young’s modulus and yield and shear strengths, respectively.

In Fig. 17(a) there is only single V-crater and it is corresponding to the cantilever beam formula (eq.1) but for the case that the coefficient k ₁ =0; so is the detailing in Fig. 17(c) but the L in (eq.1) is doubled because a pair of opposite V-craters present. For both cases, pin

1 is anchored to the pier by cast-in the concrete. By contrast, the embodiment of hinged pin 2 is depicted in Fig. 17(b) which is able to be analyzed by (eq.4) when the crater’s curvature is designed with asymptotic contact; otherwise (eq.l) is suitable for the case in

Fig. 17(b) but the coefficient k ₂ =0. Optional parts are the bottom pad 5, top pad 7, and friction washer 6 in Fig. 17, which provide the functions of weight-transferring and lubrication. By this art the apparatuses 17(a) and 17(c) are categorized as “Class I V- Connection with Posttension”; the pin with hinged end in Fig. 17(b) is categorized as the

“Class II V-Connection with Post-tension”.

Fig. 19 presents the combination of V-shaped crater and anchor pin but with additional V-shaped Guiding Tube (VGT) 9 or separated Protection Funnel 10 and

Protection Tube 11, respectively, which protect the matrix of connected from the damage due to the contact to the pin.

By quantitative calculation using eqs.(l-4) according to Figs. 18(a, b), one may find that a relatively large value of L, the depth of the crater, is needed to bring up remarkable uplift force to affect lateral resistance because the enhanced angle β is generally small for a deformed metal cantilever. On the other hand, when the uplift mechanism becomes dominant, it will also simultaneously introduce significantly high shear force to the pin. To improve the performance profoundly without increasing the size L, an additional embodiment is introduced in Fig. 20(a) where a combination of the V-shaped Socket 12, termed V-socket thereinafter, and the Contact Pad 14 is introduced in the design detailing, where the Contact Pad 14 can be either the bottom pad 5 or the top pad 7 in Fig. 17. With the function to reinforce the pin, similar to that introduced by the shear reinforcement-ring in Fig. 13, the innovative feature of V-socket 12 is with a designated V-slope with the angle β that provides quantified uplift force, according to mechanism explained by Fig. 18(b).

The connection with V-shaped socket is categorized as “Class III V-Connection with Post- tension”, for example, that in Fig. 20(b).

Instead of V-shaped socket 12, an embodiment presented in Fig. 20(c) is the design of the pin 13 with locally enlarged diameter to gain designated angle β for uplift- mechanism in Fig. 18(b) and simultaneously reinforce the pin against shear force. Additionally, the embodiment to hinge the end of pin 2 in Fig. 17(b) is also applied to the pin 13 in Fig. 20(c) with a friction washer 6 between the contact surface-pair.

Obviously, when the uplift motion explained in Fig. 18 occurs, it will create additional tension force on the anchor pin 1 oo 2 or 13 in these figures. To reduce the amplitude of this additional tension stress and accommodate large-scaled uplift motion, a buffer spring 18 is added to the detailing in Fig. 20(c), which belongs to the “Class Π V-

Connection with Post-tension”.

Fig. 21 (a) is the case that a V-socket 12 is completely fill into the space of V-shaped crater 3, where the underlying embodiment is to use the socket as a shear key to reinforce the pin enclosed and to position the blocks to be connected. This detailing is more suitable to connect multiple structural components vertically or horizontally. Fig. 21(c) also introduces the embodiment to form a structural reinforcement-line for posttension by connecting multiple Two-End Threaded Pin 20 using the coupler-Vsocket 19. The coupler- socket is with polygon head for fastening, which fills into 43, the V-shaped crater with additional cylinder-shaped cavity at it bottom. In summary, Figs. 21 (b, c) brief the embodiment of the construction process for the dry connection of multiple vertically aligned structural components, implying the following three enhanced structural functions:

(i) connecting plural pins or rebars to form the structural reinforcement-line for a post- tension operation; (ii) reinforcing the structural reinforcement-line at the areas around contact surface-pair by the V-shaped socket or the coupler-Vsocket; (iii) positioning these structural blocks by the V-shaped sockets or the coupler-Vsocket The connection with coupler-Vsocket such as that in Figs. 21(a-c) is categorized as “Class IV V-Connection with Post-tension”. Utilizing a pin to connect two structural parts, while restricting lateral relative motion in-between, is a common method for engineering design that has been applied centuries; but, by the author’s best knowledge, for the all pin-like connectors applied for bridges and buildings so far, the two end parts of a pin are respectively embedded into the connected structural components without proximity except those Figs. 12-14, the prior arts by the applicant of this invention. However, the embodiments disclosed in those arts pin was not anchored for post-tension nor the uplift mechanism having been considered in associated designs. Furthermore, a combination of the embodiment of V-sockets in Figs.20 with the enclosed pin can also be viewed as a sort of pins for connection but with an innovative feature of the locally enlarged diameters around connection interface. This leads to the embodiment in Fig. 22(a), “Atypical Pin” 48, which is characterized by the combined functions that consist of (i) the segments with the lengths L _V2 , L _v3 , L _c0 and the diameters greater than other segments are designed for shear-reinforcement and positioning; (ii) the cylinder segments with the lengths L _c2 and L _c1 are designed for sufficient holdings provided by connected units’ bodies; (iii) the segments with the lengths L _V1 and L _V4 and V-shape, reduced diameters are designed for guiding-positioning; where (i) is an innovative feature beyond conventional pins that This Atypical Pin 48 is abbreviated as “Al-pin” thereinafter. The Atypical Pin 49 is a degenerated case of Al-pin where L _V1 = L _V4 = 0, abbreviated as “A2-pin” thereinafter, whereas the Atypical Pin 50 is another degenerated case of Al-pin where L _v2 = L _v3 = L _c0 = 0, abbreviated as “A3-pin” thereinafter.

When the atypical pins in Fig. 22(a) are designed with centered through-cylinder hole where a pin or tendon goes through, it leads another embodiment for a class of innovative sockets designed with extra shear-reinforcement around the interface between two connected units for posttension while assisting positioning for assembling, termed “V- shaped shear key” or abbreviated as “V-shear key” thereinafter. These depicted in Fig.

22(b) are the V-shear key denoted as V1-shear key for the socket 51, V2-shear key for the socket 52, V3-shear key for the socket 23, respectively. The V-socket 12 introduced previously in Fig. 20 can be considered as a degenerated case of VI -shear key 51 where

L _v2 = L _v3 = L _c0 = L _c1 = L _c2 = 0; similarly degeneration for the VI -socket 53 in Fig.

22(c) but L _V1 ≠ L _v4 . Fig. 23(c) demonstrates how these V-shaped shear key works for posttension with extra reinforcement to the pin or tendon that goes through connected units around the contacted interface between the units.

For the cases that structural blocks are piled-up and post-tensioning vertically, e.g.

Figs. 21(a-c), these blocks’ weights introduces additional friction force on their contact surface-pairs added up to the friction by posttension, which helps resists any relative sliding and be beneficial to connected structure’s integrity. By contrast, for the post-tension of horizontally aligned structure blocks, for example, precast segmental bridge’s blocks in

Fig. 23, structures’ weight is completely transferred into the shear force on contacted surface-pair. The V-shaped shear keys and pins in Fig. 22 are suitable for this kind of applications. An example of segmental bridge span’s posttension with the V-shear key 23, in conjunction with V-shaped Guiding Crater 27 to fit the V-shaped shear key, is presented in Fig. 23.

Figs. 24(a,b) present the construction processes of a wet-joint to connect two-sets of I-girder 33 on the bent 28 topped on the pier 29 with posttensioning both vertically and horizontally, where the tendon conduit 30 are precast within each I-girder 33 and the posttension operation consists of two steps: (i) fasten the anchor nut 4 during or after the cast-in process of the wet joint depending upon the location of anchor site, which imposes compression vertically to the joint; (ii) insert the tendon 35 through the conduit 30 that connects the ducts precast respectively in the wet joint and each I-girder 33 and impose horizontal posttension to the tendon. In Fig. 24(b) the vertical posttension is performed during the cast-in process for the wet joint The wet joint in Fig. 24 comprise two kinds of design-detailings: (i) when seismic isolation is the primary consideration, the pad 32 and the buffer material or bearing pad 34 are set in whereas the V-shaped Socket 12 is not completely filled into the space enclosed by the V-shaped crater; so the pins are able to be bent within the craters and relative lateral sliding may occur, which brings in the effect of seismic isolation while triggering the uplift mechanism to utilize the weights of the carried supper-structure to resist lateral sliding. The combination of the pin, V-crater, and V-socket or V-shear key can be designed always in revisable elastic condition according to eqs.(4-

6), so the structure is with sufficient capacity to drive the connection back to original state with engineering-acceptable tolerance after the impact that caused the relative sliding is passed, (ii) When structural integrity is the dominated consideration, the girders are directly laid on the bent’s top, so is the wet-joint to be cast; there is no need of the pad 32 and the buffer material or bearing pad 34 but the V-shaped socket or V-shaped shear key is installed on the connection to pier to protect the pin.

Figs. 25 introduces the construction processes for the same application as that in

Figs. 24 but instead of, applying the dry connection by the box-joint 36 or block-joint 37.

In these dry connection blocks, ducts 44 for vertical reinforce pin 1 and ducts 45 for horizontal tendons are precast The posttension operation is executed by fastening the nut

4 on the top of a dropped-in dry-joint block, e.g. 36 or 37. Dry connection in Fig. 25 may need accurate alignment of I-girders along longitudinal location so as to assure the width of the gap between connected girders fits the size of dry-joint block and the tolerances of the girders' lengths and construction can be accommodated by deck’s joint-expansion. This can be tedious and even infeasible for a bridge with multiple spans. This drawback can be solved by applying the combination of wet and dry joints, one next to another, as illustrated in Fig. 26.

Applying the innovative design detailings introduced previously and the procedures introduced in Figs. 24 - 26, a construction process of a crossing-joint in three ways for a building structure is presented in Fig. 27.

Validation and Experimental Verification for Key Embodiments

Series experimental investigations and numerical simulations had been conducted to verify the concepts introduced for the V- connectors without posttension in prior arts by the author of this art, for examples, these in [1], The results of these research-works have actually inspired the embodiments disclosed in this art

Computational simulations were conducted for a series of 3D FE models of a bridge span-pier connection via embedded regular pin-connection or pin in V-shaped crater, with or without the V-shaped socket introduced in Fig.20. The investigation compared the performance of three types of methods: (i) a connection using a conventional pin within a cylindrical hole in the concrete matrix; a corresponding 3D FE mesh is given in Fig. 28(a);

(ii) a connection using straight pin within a V-shaped crater as depicted in Fig. 28(e), a corresponding 3D FE mesh is given in Fig. 28(b); (iii) a connection using straight pin with the V-shaped socket within a V-shaped crater as depicted in Fig. 28(f), two FE meshes for different sizes are presented in Fig. 28(d), which are computed for design optimization. In these two meshes of Figs. (c,d), the V-shaped socket is meshed as a part of the pin; also, the two ends for pin are respectively meshed as parts of the upper and lower blocks, so as to avoid sophisticated meshing for the anchor parts. These simplifications do not affect the mechanical behavior of the connectors.

The corresponding simulations included two groups: group I: the FE models in

Figs.28(a,b,c) where the specimens are with the same vertical load, horizontal acceleration, friction coefficient, and materials for the pin, tube, and concrete matrix; as well as the same diameter for the straight pin and for the straight part of the pins with varying parameters; group Π: the FE model for the mesh in Fig. 28(d) where the sizes of the pin and V-shaped socket are larger than others, which is under the same vertical load as other but higher amplitude of the horizontal.

Fig. 29 presents a comparison of the computed contours of Von Mises stress for the cases in Fig. 28(a) and 28(b) under the same load condition, where, theoretically speaking,

Von Mises stress is the shear stress on octahedral body, which equals to the maximum engineering shear stress times V2. As discussed in previous section, for the case of conventional pin inserted in cylinder holes in Fig. 28(a), the computed results in Fig. 29(a) demonstrates significant high concentration of shear stress at the local area around the contact interface between the upper span-block and the lower pier-block, which actually cut the pin soon. By contrast, for the case of the pin within the V-shaped crater, the computed results in Fig. 29(b) indicate high shear presents at the areas near the crater’s bottom, where the pin starts to contact the crater. In the latter the amplitude of the stress peak is much lower than that in Fig. 29(a). Fig.30 is a series of snap-shots of the contours of computed contours of Von Mises stress for the case in Fig. 28(c) under progressively increasing lateral load Q denoted in Fig. 18, which demonstrates that, when the lateral load

Q is greater than Q _f , a threshold value of the lateral load, liftup-mechanism of becomes significant. These phenomena replicated by numerical computations proofs the concepts of the embodiments in Fig. 18, which actually inspired the embodiments in this art.

The experimental verifications of the product-family of V- Connectors have been conducted simultaneously in the PEER Lab. (Pacific Earthquake Engineering Research

Center) at University of Berkeley, United States, and the Heng-Shui Earthquake Research

Lab.(HSER) of Heibei Province, China. These experimental investigations were originally designed for the products based on the embodiment of V-connector with Hinged-Pin in

Fig.14, for which only one end of the pin is hinged as that in Fig. 17(b) but another end is free. However, by the tests the phenomenon of uplift has been observed that verified the computer simulation in Fig. 29, which actually inspired the invention presented in this art.

Fig.31 is a photo of the test facility setup in the PEER Laboratory, UC Berkeley, California.

Fig. 32 is a photo of the facility in HSER of China. Fig. 33 is a group of measured hysteretic curves for a V-connector specimen according to the embodiment in Fig. 20(c) connecting a bridge span-block above and a pier block below, the same as the model in Fig. 28. In the figure the horizontal axis is the lateral displacement and the vertical axis is the corresponding lateral resistance of that was tested. In this figure the lateral displacement is actually the relative sliding between the span block and the pier block; the lateral resistance denoted by the vertical coordinate is the force against this relative sliding produced by the

V-connector installed and the friction force on the contact surface-pair between two blocks.

One can see a dramatically increasing of the resistance when the relative sliding surpasses

80 millimeters, which is about the radius of the opening for V-shaped crater in the V- connector specimen tested. The suddenly elevated resistance at that distance implies the pin touches the edge of the top pad that brought up uplift mechanism. This result verifies the key embodiment in Fig. 20 and validates the feasibility of the V-connector for engineering applications.

Brief Description of the Drawings

For a more complete understanding of the prior arts, the present disclosure, and the advantages thereof, references are now made to the following conjunction with the accompanying drawings, wherein:

Fig. 1(a) explains how the tension stress to be induced in a flexure beam under bending if there is no posttension; by contrast, Fig. 1(b) presents a schematic diagram to illustrate the process of posttension that prestresses the beam with compression, the corresponding compressive stress trades of the tension stress in (a) when the beam is under bending moment

Fig. 2 highlights the engineering problems to be solved by this invention, which presents two common examples of crossing joints to highlight the complexity in stress distribution; to assure tension and shear stresses in concrete part of these kinds of joints remains as a challenge to the conventional posttension methodology in Fig.l, where the two examples are: (a) a common joint between girders and bent on a bridge’s pier top and (b) a crossing- joint of beams with column for building.

Fig. 3: (a) The prior art US3899891, where a pile is an assembly of a plurality of vertically arranged, tubular driving shell sections joined one by one with a through prestressing tendon; (b) The key embodiment of the prior art US3703748 that introduces the detailing of wedged anchors to the tendon’s two ends. Fig. 4: (a) the embodiment of the prior art US 1647925 that utilizes a steel socket at footing to anchor a rod tendon’s low end and a nut to fasten the rod at its upper end over a pile’s top; (b) a recent patent application (CN110685215A/CN201910897918A ) that is similar to the concepts in prior art US3899891 and US1647925 but additional steel sleeves are engaged to connect the rebars in adjacent pile-segments just above their contact surface- pair; (c) another recent application (CN109610304A/CN201811608588.3) where the detailing of socket 8 with constant sectional geometry is presented at the contact surface- pairs to protect the tendon for posttension.

Fig. 5 presents two kinds of couplers: (a) the device to connect two tendons’ ends that are not aligned on one axis, US 6560939B2; (b) a threadable coupler for two rods with threatened ends along the same axis, PCT/KR2006/004958.

Fig. 6 is the prior art US6742211 with the embodiment of bridge assembly with the piles made by vertically overlaid structural blocks over matched concave-convex downward contact surface-pair to increase lateral resistance against dislocation.

Fig. 7 presents a method to construct a wet joint between two bridge’s spans over a pier in the prior art US3794433, which probably have brought a revolutionary progression for concrete bridge’s construction with posttension.

Fig. 8 is a crossing-joint of two posttension conduits with saddle anchorages in US2950517 for a part of a crossing arranged tendon network embedded in a highway’s deck.

Fig. 9 is the prior art JP2011001717A(Japanese patent) to deal with crossing joint of concrete beams to a column overlaid, where the embodiment is the side-bolted steel-set that assures the column standing vertically and enables the gap between the column’s bottom and the crossing-joint of the beams to be adjustable. Fig. 10 is the design detailing by Tennessee State Department of Transportation of USA, which defines the common procedure to cast wet joint connecting two spans over the top of a column that can be either a pier or a bent over a pier, by which a bolt was first been cast into the column; then two spans' ends were dropped on the column’s top at the two sides of the bolt; then cast concrete-mix into the gap between the two spans’ ends while the bolt is fastened to impose compression on a part of the joint; where (a) and (b) are two standard design drawings where in the former an elastomeric pad is set beneath the joint, whereas a bituminous fiberboard is applied as bearing pad. The network layout of rebar within the wet joint is given in (c). However, high shear stress concentration, like that depicted in the left plot of Fig. 13, presents at the interface between the pier and the wet joint when the structure is struck by a strong earthquake.

Fig. 11 is the prior art JP200 8050820A(Japanese patent) that introduces the vertical connection of two structural blocks over V-shape sliding contact surface-pair and an anchored bolt fastened at top. To accommodate horizontal sliding separation along the V- shaped surface, a hole with the diameter larger than the bolt is prefabricated in the upper block so the bolt can move freely within the hole, which essentially trades off the solidity of the connection provided by the top fastening.

Fig. 12 is the embodiment by the prior art PCT/US2016/013741, this inventor’s prior art, which utilizes a combination of a pin through V-shaped crater to connect a bridge’s pile to beam to gain increasing capacity against lateral shear but without the means for posttension. Fig. 13 is an additional embodiment in PCT/US2016/013741, which introduces various designs of the pin’s geometries featured by locally enlarged diameter or employing additional shear reinforcement-ring to increase the capacity against lateral shear force.

Fig. 14 is the embodiment by the prior art PCT/US2018/013205, this inventor’s another prior art; instead of the V-shaped craters in both surfaces to the two connected structural blocks, only one V-shaped crater presents in the connector but with fix-end pin or hinge- end pin.

Fig. 15 is the embodiment of the friction pendulum bearing (FPB) by prior art US6021992, among a group of other prior arts of FPB. Based on the principal of the pendulum depicted on the right-hand side of the figure, the apparatus uses carried superstructure’s weight- induced lateral force-resultant on arc surface to resist horizontal inertia caused by ground motion, however, there is no restriction of vertical separation among the connected structural components.

Fig. 16 is the embodiment by the prior art PCT/US2012/0613127, the applicant’s another invention, which utilizes the horizontal resultant of carried superstructure’s weight on V- shaped sliding surface to resist earthquake-induced lateral dislocation, whereas the horizontal sliding-pin in (a) or vertical reinforce-pins (termed fastener) in (b), respectively, confines connected structural components without vertical separation.

Fig. 17 presents the key embodiments of this invention featured by the combinations of the

V-shaped crater 3 and the anchored pin 1 precast in the lower block or the pin 3 hinged into this block for posttension, where the benefits of the V-shaped crater 3 include: (i) providing a “buffer space” for pin’s bending when the structures is struck by extreme high external load such as strong earthquake and the relative sliding is inevitable, so as to avoid the pinto be cut by the shear stress concentration explained by the left-most plot in Fig. 13;

(ii) introducing an uplift motion of the connected upper structural block, so as to utilize the horizontal resultant of the block’s weight introduced by the curvature of the pin to against an earthquake-induced lateral motion, which will be further explained in Fig. 18; (iii) providing the room to reinforce the pin and to enlarge the effect of uplift. The design detailing of the connections for posttension featured by the V-shaped crater with conventionally anchored end in Figs. 17(a) and (c) are categorized as the “Class I V-

Connection with Post-tension”, the pin with hinged end in Fig. 17(b) is categorized as the

“Class II V-Connection with Post-tension”.

Fig. 18 (a) the curve for the outline of the V-shaped crater 3 in Fig. 17(b) or that in

Fig.(17c), denoted as Y(x); which is designed according to the bending configuration for half length of the pin 1 in Fig. 17(c) or that for entire length ofthe pin 2 in Fig. 17(b), under a lateral force Q, which, if designed according to eq.(1-6), may introduces asymptotic contact between the pin and the crater’s surface, so as to produce gradually increased shear force on the pin as explained in (b); (b) when the pin is bent, the lateral force Q is divided into the resultant Q normal to contact surface and the resultant N tangential to it, depending up the angle β that can be approximated by the derivative of the function determined by equations 1 - 4; a reactant against N, comes from the upper block’s weight, will be induced that contributes to resist further lateral displacement; (c) a model for the asymptotic contact between pin and V-shaped crater, by which the first ordinary differential equation 4 has been derived to determine the curvature of the V-shaped crater.

Fig. 19 To protect concrete matrix, additional V-shaped Guiding Tube (VGT) 9 or separated Protection Funnel 10 and Protection Tube 11, respectively, have been added Fig. 20 (a) an innovative detailing of a part-pair of V-shaped Socket 12 and Contact Pad

14, which enables to select an angle β in Fig. 18(b) for designated uplift effect; this leads to the embodiments for the “Class Π V-Connection with Post-tension” in (b) and (c), respectively; where (b) is a direct application of the part-pair in (a) for the connections in

Fig. 17(a); by contrast, the embodiment of hinged pin in Fig.17(b) applies in (c) but the pin is with gradually enlarged diameter, denoted as 13. According to the mechanism introduced in (a), the V-shaped socket 12 also reinforces the pin’s strength against shear; the detailing in (c) comprises a spring 18 that work as a buffer to accommodate uplift motion, so as to reduce tension stress in the pin.

Fig. 21(a) presents a detailing that the V-shape Socket 12 is completely fill into the space of V-shaped crater 3, where the underlying embodiment is to use the socket to reinforce the pin while positioning the two blocks to connect When plural structural blocks are connected by this method for posttension, an embodiment to adopt the V-shape Socket as a coupler for pins by internally threading and a nut-head is detailed in (c), which is termed coupler-Vsocket and denoted as 19 in (b) and (c) of this figure; so the V-shaped crater for coupler-Vsocket also comprises an additional cylinder-shaped cavity at its bottom and denoted as 43 in this figure; and the pins are also with threaded two ends except the one end anchored at bottom; this kind of pins are denoted as 20 in these plots. The V-connectors with this detailing are categorized as the “Class IV V-Connection with Post-tension”.

Fig. 22 (a) Atypical Pin: Al-pin 48 where the segments with the lengths L _V2 , L _v3 , L _c0 are designed for shear-reinforcement and positioning; the cylinder segments with the lengths L _c2 and L _c1 are designed for sufficient holdings; the segments with the lengths Lvi and L _V4 and V-shape reduced diameters are designed for guiding-positioning. A2-pin 49 is a degenerated case of Al-pin where L _V1 = L _v4 = 0, whereas A3-pin 50 is another degenerated case of Al-pin where L _v2 = L _v3 = L _c0 = 0 , respectively, (b) When the atypical pins in Fig. 22(a) are designed with centered through-cylinder hole where a pin or tendon goes through, it leads another embodiment for a class of innovative sockets designed with extra shear-reinforcement around the interface between two connected units for posttension while assisting positioning for assembling, termed “V-shaped shear key”, or abbreviated as “V-shear key”, a class of innovative sockets designed with extra shear- reinforcement around the interface between two connected units for posttension while assisting positioning for assembling, parallel to the embodiment in (a); the V-socket 12 introduced previously in Fig. 20 can be considered as a degenerated case of the VI -shear key 51 that L _v2 = L _v3 = L _c0 = L _c1 = L _c2 = 0; similarly for the VI -socket 53 in (c) where L _V1 ≠ L _V4 . Fig. 23(c) demonstrates how these V-shaped shear key works for posttension with extra reinforcement to the pin or tendon that goes through connected units around the contacted interface between the units, demonstrates how these V-shaped shear key works for posttension with extra reinforcement to the pin or tendon that goes through connected units.

Fig. 23 is an example of a segmental bridge span’s posttension where plural V-shear key

23 disclosed in Fig. 22, in conjunction with V-shaped Guiding Crater 27 to fit the V-shaped shear key, are applying.

Fig 24 presents the construction processes of a wet-joint to connect two-sets I-girders 33 on the bent’s top 28 of pier 29 with posttension vertically through the pin 1 reinforced by the V-socket 12 or V-shear key 23 and the tendon 35 horizontally; where (a) depicts the parts and components between cast-in the wet joint; (b) presents the wet joint after cast-in. Additionally, the vertical posttension is executed by fastening the pin 1 by anchor nut 4 at the middle of the wet joint The combination of the pin, V- crater, and V-socket or V-shear key can be designed always in revisable elastic condition according to eqs.(4-6), so the structure is with sufficient capacity to drive the connection back to original state with engineering-acceptable tolerance after the impact that caused the relative sliding is passed.

Fig. 25 presents the construction process that is the same as that in Fig. 24 but instead of wet-joint, a dropped-in dry joint-box 36 or dry joint-block 36 is applied. Different from the wet joint in Fig. 24, the vertical posttension is executed by fastening the pin 1 by anchor nut 4 on the upper surface of the dry joint-block.

Fig. 26 In order to fit the gap between two connected girders when dry joint-block or joint- box is applied and assure that bridge deck’s expansion joint is able to accommodate the tolerances due to the girders’ fabrication and construction, this figure introduces a construction process that applies one wet-joint after one or two dry joints to accommodate the deviations in manufacturing and construction of dry joint for multi-span bridges.

Fig. 27 presents the construction process of a three- ways crossing-joint for a building structure applying the connection detailing disclosed previously and posttension methods introduced in Figs. 24 - 26.

Fig. 28 presents the four typical 3D FE models of a bridge span-block connected to a pier block by V-connector; by these models the numerical simulations have been carried out to verify the concepts based on the embodiments disclosed in this art and to find optimized design parameters for industrial applications; where (a) is a conventional pin connection within cylinder holes; (b) to (c) are the models for V-connectors according to the embodiment (e) for that in Fig. 17 and (f) for that in Fig. 20. In the models (c) and (d) the V-shaped socket is modeled as a part of the pin; whereas the anchor ends in models (b,c,d) are modeled as a solid connection to the blocks.

Fig. 29 is a comparison of the computation results between the case (a) and case (b) in Fig.

28; where high shear stress concentration occurs at the interface between two blocks in (a), the conventional pin-connection; by contrast, the highest shear stress with moderate amplitude presents around the areas where the pin contacts the V-crater.

Fig. 30 presents a series of snap shots of the case (c) in Fig. 28, where the uplift phenomenon shows off in (d) when the lateral force Q reaches to the certain level.

Fig. 31 is the test facility in the PEER lab., Department of Civil and Environmental

Engineering, University of California at Berkeley; the facility was set up to test the performance of V-connector for the physical model similar to these in Fig. 28.

Fig. 32 is the test facility in the Heng-Shui Earthquake Research Lab (HSER) of Heibei

Province, China for the test of V-connector.

Fig. 33 is a group of measured hysteretic curves of the V-connector according to the embodiment in Fig. 20(c) where the horizontal coordinate represents the lateral displacement and the vertical coordinate is the lateral resistance; a dramatically increasing of the resistance is showing off when the lateral displacement surpasses 80 millimeters, which is about the radius of the opening for the V-shaped crater in the specimen tested, which implies the effect of uplift mechanism.