JP7788102B2 - Seismic isolation and earthquake resistance structures for buildings made of both wood and lightweight steel - Google Patents

Description

This invention relates to seismic isolation and earthquake resistance structures for buildings constructed using both wooden and lightweight steel frames.

One such earthquake-resistant structure for wooden buildings is disclosed in Patent Document 1. This earthquake-resistant structure for wooden buildings involves fixing connecting members, which are mounting brackets, to the four corners between a pair of cross members and a pair of columns, and fastening both ends of braces with bolts and nuts through diagonal brace fixing holes formed in the corners of the connecting members located at each diagonal corner. In other words, earthquake-resistant strength is ensured by fixing the braces to each corner in an X-shape.

JP 2019-65590 A

However, in the earthquake-resistant construction of conventional wooden buildings, the corners of the connecting members are bolted to the ends of the braces in a single shear connection, so in order to firmly connect the two and maintain high earthquake resistance, the ends of the braces must be fastened and secured with multiple bolts.

The present invention was made in consideration of the problems inherent in the prior art. The object of the present invention is to provide a seismic isolation and earthquake resistance structure for a combined wooden and lightweight steel-framed building that secures high seismic isolation and earthquake resistance performance by firmly joining gusset plates and braces with double shear joints.

The seismic isolation and earthquake-resistant structure for a combined wooden and light-gauge steel-framed building according to one aspect of the present invention comprises gusset plates attached to each of the diagonally opposing corners between adjacent left and right columns and adjacent upper and lower cross members of the combined wooden and light-gauge steel-framed building, and a pair of braces that are bolted to both ends of the gusset plates that are sandwiched between the pair of braces and joined in double shear by the bolts.

According to the present invention, by sandwiching a gusset plate between a pair of braces and connecting them in double shear with a single bolt, it is possible to improve shear strength and provide a seismic isolation/earthquake-resistant structure for a combined wooden and lightweight steel-framed building that ensures high seismic isolation/earthquake-resistant performance.

1 is a side view showing an example of a seismic isolation and earthquake-resistant structure (framework) of a combined wooden and light steel frame building according to an embodiment of the present invention. FIG. FIG. 2 is an enlarged side view of part A of FIG. 1. 1A is a side view showing the columns on the first floor of the above-mentioned wooden and light steel frame building, and FIG. 1B is an enlarged cross-sectional view taken along line H-H in FIG. 1A. 1(a) is a side view showing the columns on the second floor of the above-mentioned wooden and light steel frame building, and FIG. 1(b) is an enlarged cross-sectional view taken along line II in FIG. 1(a). FIG. 3 is an enlarged side view of part B of FIG. 2. FIG. 6 is a cross-sectional view taken along line JJ in FIG. 5. 1A is a side view of the support pillar mounting bracket used in the seismic isolation/earthquake-resistant structure, FIG. 1B is a rear view of the support pillar mounting bracket, and FIG. 1C is a plan view of the support pillar mounting bracket. 1A is a side view of a gusset plate as a brace mounting bracket used in the seismic isolation/earthquake-resistant structure, FIG. 1B is a rear view of the gusset plate, and FIG. 1C is a plan view of the gusset plate. 3A is an enlarged side view of part C in FIG. 2, FIG. 3B is a side view of the gusset plate located on the left side in FIG. 3A, and FIG. 3C is a side view of the gusset plate located on the right side in FIG. 3A. FIG. 10 is a cross-sectional view taken along line K-K in FIG. 9. 1A is an enlarged side view of part D in FIG. 1, FIG. 1B is a side view of the gusset plate located on the left side in FIG. 1A, and FIG. 1C is a side view of the gusset plate located on the right side in FIG. 1A. FIG. 3 is an enlarged side view of part E in FIG. 2. 13 is a cross-sectional view taken along line L-L in FIG. 12. This is a cross-sectional view taken along line L'-L' in Figure 12. FIG. 3 is an enlarged plan view of the crossing portion of the brace, which is part F in FIG. 2 . FIG. 3 is an enlarged side view of a portion G in FIG. 2. 17 is a cross-sectional view taken along line MM in FIG. 16.

The following describes in detail, using drawings, the seismic isolation and earthquake resistance structure of a combined wooden and light steel frame building according to an embodiment of the present invention.

Figure 1 is a side view showing an example of a seismic isolation/earthquake-resistant structure (frame) for a combined wooden and light-gauge steel-framed building according to an embodiment of the present invention. Figure 2 is an enlarged side view of portion A in Figure 1. Figure 3(a) is a side view showing a column on the first floor of a combined wooden and light-gauge steel-framed building. Figure 3(b) is an enlarged cross-sectional view taken along line H-H in Figure 3(a). Figure 4(a) is a side view showing a column on the second floor of a combined wooden and light-gauge steel-framed building. Figure 4(b) is an enlarged cross-sectional view taken along line I-I in Figure 4(a). Figure 5 is an enlarged side view of portion B in Figure 2. Figure 6 is a cross-sectional view taken along line J-J in Figure 5. Figure 7(a) is a side view of a support pillar mounting bracket used in a seismic isolation/earthquake-resistant structure. Figure 7(b) is a rear view of the support pillar mounting bracket. Figure 7(c) is a plan view of the support pillar mounting bracket. Figure 8(a) is a side view of a gusset plate as a brace mounting bracket used in a seismic isolation/earthquake-resistant structure. Figure 8(b) is a rear view of the gusset plate. Figure 8(c) is a plan view of the gusset plate. Figure 9(a) is an enlarged side view of portion C in Figure 2. Figure 9(b) is a side view of the gusset plate located on the left side in Figure 9(a). Figure 9(c) is a side view of the gusset plate located on the right side in Figure 9(a). Figure 10 is a cross-sectional view taken along line K-K in Figure 9. Figure 11(a) is an enlarged side view of portion D in Figure 1. Figure 11(b) is a side view of the gusset plate located on the left side in Figure 11(a). Figure 11(c) is a side view of the gusset plate located on the right side in Figure 11(a). Figure 12 is an enlarged side view of portion E in Figure 2. Figure 13 is a cross-sectional view taken along line L-L in Figure 12. Figure 14 is a cross-sectional view taken along line L'-L' in Figure 12. Figure 15 is an enlarged plan view of the brace intersection, which is portion F in Figure 2. Figure 16 is an enlarged side view of portion G in Figure 2. Figure 17 is a cross-sectional view taken along line M-M in Figure 16.

As shown in Figure 1, the seismic isolation and earthquake-resistant structure 10 of the combined wooden and lightweight steel-framed building 1 includes gusset plates 30, 35, and 36 attached to each diagonally opposing corner 20 between adjacent left and right columns 11 (11') and adjacent upper and lower cross members 21, 26, and 22 (22, 26, and 24), and a pair of braces 40, 40 that sandwich and bolt each gusset plate 30, 35, and 36 at its end. Here, reference numeral 21 denotes a concrete or wooden base serving as the lower cross member, reference numeral 22 denotes a girder (or beam) serving as a cross member located between the upper end of the first-floor column 11 and the lower end of the second-floor column 11', reference numeral 24 denotes a girder (or beam) serving as a cross member located between the upper ends of the second-floor columns 11', and reference numeral 26 denotes a horizontal cross member located midway between each column 11 and 11'.

As shown in Figures 1 and 2, multiple first-floor columns 11 are supported upright at predetermined intervals on concrete foundations 2 and bases 21. Furthermore, as shown in Figures 1, 2, and 5, anchor bolts 3 are embedded in the foundations 2 to fasten and secure the lower ends of the first-floor columns 11. The threaded portions 3a of these anchor bolts 3 protrude outward from the top surface of the foundations 2. Furthermore, the bases 21 are formed in a rectangular frame shape to connect multiple foundations 2 together.

As shown in Figures 1 to 4, 13, and 17, the first-floor column 11 and the second-floor column 11' have four C-channel (C-shaped) steel members 12 bolted together in a cross-shaped configuration in plan view, and rectangular wooden pieces 13 inserted into each C-channel steel member 12. Multiple bolt insertion holes 12b for bolt fastening are drilled at the top, middle, and bottom positions of the paired L-shaped bent portions 12a of each C-channel steel member 12. The four C-channel steel members 12 with adjacent paired L-shaped bent portions 12a are fastened and fixed in a cross-shaped configuration in plan view by tightening bolts 5 inserted through five bolt insertion holes 12b positioned at equal intervals from top to bottom and nuts 6 threaded onto the bolts 5.

As shown in Figures 5 and 6, the lower ends (ends facing the foundation 2) of the four C-channel steel members 12 of the first-floor columns 11 are fastened and fixed via support mounting brackets 15 by tightening nuts 4 threaded onto the threaded portions 3a of anchor bolts 3 protruding above the foundation 2.

As shown in Figures 5 to 7(a), (b), and (c), the pillar mounting bracket 15 has a trapezoidal right-angled side plate 15a with two upper and lower bolt insertion holes 16b, and a triangular bottom plate 15c bent from the bottom end of the right-angled side plate 15a and formed with a semicircular notch 15d for receiving an anchor bolt. Furthermore, as shown in Figures 8(a), (b), and (c), the gusset plate 30 serving as a brace mounting bracket is bolted to the bottom end of the pillar 11 so that it mates with the triangular bottom plate 15c of the pillar mounting bracket 15. It is made of steel and has a roughly trapezoidal right-angled side plate 31 with a total of three bolt insertion holes 32 drilled above, below, and diagonally upward, and a triangular bottom plate 33 bent from the bottom end of the right-angled side plate 31 and formed with a semicircular notch 34 for receiving an anchor bolt.

As shown in Figure 5, when fixing the column 11 to the foundation 2, first, as shown in Figure 6, the right-angle side plates 15a, 15a of the two column mounting brackets 15 are sandwiched between the opposing bent portions 12a, 12a of the two C-channel steel members 12 on the lower side of the column 11 in Figure 6, and then fastened and fixed together with bolts 5 and nuts 6. Next, the right-angle side plates 15a, 15a of the two column mounting brackets 15 are sandwiched between the opposing bent portions 12a of the two C-channel steel members 12 on the left side of the column 11 in Figure 6, and then fastened and fixed together with bolts 5 and nuts 6. At this time, the semicircular notches 15d, 15d of the triangular bottom plates 15c of the two column mounting brackets 15 are aligned to form bolt insertion holes for the anchor bolts 3. Similarly, the right-angle side plates 15a, 15a of the two pillar mounting brackets 15 are sandwiched between the opposing bent portions 12a of the two C-channel steel materials 12 on the upper side of the pillar 11 in Figure 6, and are fastened and fixed together with bolts 5 and nuts 6. Furthermore, the right-angle side plates 31, 31 of the two gusset plates 30 are sandwiched between the opposing bent portions 12a of the two C-channel steel materials 12 on the upper side of the pillar 11 in Figure 6, and are fastened and fixed together with bolts 5 and nuts 6. At this time, the semicircular notches 15d, 15d of the triangular bottom plates 15c of the two pillar mounting brackets 15 and the semicircular notches 34, 34 of the triangular bottom plates 33 of the two gusset plates 30 are aligned with each other to form bolt insertion holes for the anchor bolts 3. As shown in Figures 5 and 6, the triangular bottom plate 15c of each column mounting bracket 15 and the triangular bottom plate 33 of each gusset plate 30 are sandwiched between a mat washer 16 and a reinforcing washer 17, and then nuts 4 are tightened onto the threaded portions 3a of each anchor bolt 3 to fasten and secure the column 11 to the foundation 2. Furthermore, as shown in Figures 5 and 6, the right-angle side plates 31, 31 of the two overlapping gusset plates 30 are sandwiched between the lower ends 40b of a pair of braces 40, 40 and are joined in double shear by a single bolt 7 and nut 8.

As shown in Figures 1 and 2, a girder (or beam) 22 serving as a horizontal member is attached between the upper end of a column 11 on the first floor of the wooden and light-gauge steel-framed building 1 and the lower end of a column 11' on the second floor. Also, as shown in Figure 1, a girder (or beam) 24 serving as a horizontal member is attached between the upper ends of columns 11' on the second floor of the wooden and light-gauge steel-framed building 1. Furthermore, as shown in Figures 1 and 2, a horizontal beam (intermediate horizontal member) 26 is attached at the midpoint between adjacent left and right columns 11, 11' located on the first and second floors of the wooden and light-gauge steel-framed building 1. Generally, a girder is used when the distance between adjacent left and right columns 11 (11') is short, and a beam is used when the distance is long. However, in this embodiment, the symbols 22 and 24 are described as girders.

As shown in Figures 2, 9(a), and 10, the girder 22 located in the middle section has two C-channel steel members 23 bolted back to back. These two C-channel steel members 23, 23 are fastened and secured back to back via gusset plates 35, which serve as brace mounting hardware, by tightening bolts 5 inserted through bolt holes 23a drilled at both ends and nuts 6 threaded onto the bolts 5. As shown in Figure 9, the gusset plates 35 are flat steel plates with multiple bolt holes 35a formed therein. They are arranged in pairs on the left and right between the upper end of the first-floor column 11 and the lower end of the second-floor column 11'. The gusset plate 35 on one side is clamped between two C-channel steel members 12, 12 located at the front and rear of one of the first-floor column 11 and second-floor column 11', and between one end of two C-channel steel members 23, 23 of the middle girder 22, and is fastened and fixed via multiple sets of bolts 5 and nuts 6.

As shown in Figure 9(a), the gusset plate 35 on the other side is sandwiched between two C-channel steel members 12, 12 located at the front and rear of the other side of the first-floor column 11 and the second-floor column 11', and between the other ends of two C-channel steel members 23, 23 of the middle girder 22, and is fastened and fixed via multiple sets of bolts 5 and nuts 6. The lower corner 35c of the gusset plate 35 on the other side is sandwiched between the upper ends 40a of a pair of braces 40, 40, and is joined in double shear by a single bolt 7 and nut 8. Furthermore, in the case of each corner 20 of portion D in Figure 1 shown in Figure 11(a), the lower corner 35c of the gusset plate 35 is clamped between the upper ends 40a of a pair of braces 40, 40 and joined in double shear with a single bolt 7 and nut 8, and the upper corner 35b of the gusset plate 35 is clamped between the lower ends 40b of a pair of braces 40, 40 and joined in double shear with a single bolt 7 and nut 8.

Furthermore, as shown in FIG. 1, the upper girder 24 has two C-channel steel members 25 bolted back to back. These two C-channel steel members 25, 25 are fastened back to back via a gusset plate 35 acting as a brace mounting bracket by tightening bolts 7 inserted through bolt holes 25a drilled at both ends and nuts 8 threaded onto the bolts 7. Like the gusset plate 35 located in the middle tier, this gusset plate 35 is formed as a flat steel plate with multiple bolt holes 35a formed therein, and is located on either side or the left or right of the upper end of the second-floor column 11'. The gusset plate 35 is sandwiched between the two C-channel steel members 12, 12 located at the front and rear of the second-floor column 11' and between the ends of the two C-channel steel members 23, 23 of the upper girder 24, and is fastened and secured via multiple sets of bolts 5 and nuts 6. Additionally, the lower corner 35c of the gusset plate 35 is clamped between the upper ends 40a of a pair of braces 40, 40 and joined in double shear by a single bolt 7 and nut 8.

As shown in Figure 14, the crossbeam 26 has two C-channel steel members 27, 27 bolted back to back. These two C-channel steel members 27, 27 are fastened back to back with a gusset plate 36 in between by tightening bolts 5 inserted through bolt insertion holes 27a drilled a predetermined distance apart and nuts 8 threaded onto the bolts 5.

As shown in Figures 2, 12-14, 16, and 17, the gusset plates 36 serving as brace mounting brackets attached to the corners 20 of the upper and lower ends of the cross beam 26 are made of steel plate and are flat, with a trapezoidal protrusion 36a on one side and a notch 36d midway between the upper and lower sections 36b and 36c. Bolt insertion holes 36e are formed in the protrusion 36a and the upper and lower sections 36b and 36c of the gusset plate 36. The notch (part) 36d side of the gusset plate 36 is sandwiched between the two C-channel steel members 12, 12 at the front and rear of the column 11, and the gusset plate 36 is bolted in place so that the notch 36d abuts against the steel support plate 9. This support plate 9 prevents the gusset plate 36 from rotating and moving downward. As a result, part G shown in Figure 2 cannot transmit stress to the column 11, but only to the brace 40, while part E can transmit stress in two directions, to the column 11 and the brace 40. In other words, the gusset plates 36 attached to each corner 20 on both the upper and lower ends of the cross beam 26 are plates for converting axial force.

As shown in Figures 12 and 16, the upper part 36b of the gusset plate 36 is clamped between the lower ends 40b of a pair of braces 40, 40 and joined in double shear with a single bolt 7 and nut 8. Furthermore, the lower part 36c of the gusset plate 36 is clamped between the upper ends 40a of the pair of braces 40, 40 and joined in double shear with a single bolt 7 and nut 8.

As shown in FIG. 2, at each diagonally opposing corner 20 between the sill 21 (the lower cross member) and the horizontal beam 26 (the intermediate cross member), and between adjacent left and right columns 11, 11, each pair of braces 40, 40 is arranged so as to intersect alternately in an X-shape. Furthermore, at each diagonally opposing corner 20 between the horizontal beam 26 and the middle girder 22, and between adjacent left and right columns 11, 11, each pair of braces 40, 40 is arranged so as to intersect alternately in an X-shape. As shown in FIG. 15, at the intersections where each pair of braces 40, 40 intersects in an X-shape, four braces 40 are arranged so as to intersect alternately. As shown in FIGS. 15 and 16, the four braces 40 at these intersections are held in place by a pair of wooden studs 46, 46 attached to the center of the horizontal beam 26 via bent steel plates 45 for stud support. As shown in Figures 13 and 17, rectangular wooden base plates 49 are joined with nails (not shown) between the rectangular wooden pillars 13, 13 on the inside and outside of adjacent left and right columns 11, 11, forming a bearing wall 50.

As shown in Figure 1, the upper ends of the first-floor columns 11, the lower ends of the second-floor columns 11', and the middle girders 22, which do not have braces 40 as diagonal braces, are attached via steel mounting plates 37. Furthermore, the upper ends of the second-floor columns 11' and the upper girders 24, which do not have braces 40 as diagonal braces, are also attached via steel mounting plates 37.

In the seismic isolation and earthquake-resistant structure 10 for the combined wooden and light-gauge steel-framed building 1 according to the above embodiment, as shown in Figures 5 and 6, at the lower end of the column 11 fixed to the foundation 2, the right-angle side plates 31, 31 of two overlapping gusset plates 30 are sandwiched between the lower ends 40b of a pair of braces 40, 40 and joined in double shear by a single bolt 7 and nut 8.

Furthermore, as shown in Figures 9(a) and 11(a), at the upper ends of the first-floor columns 11, the lower ends of the second-floor columns 11', and the ends of the middle girders 22, the lower corners 35c of the gusset plates 35 are clamped between the upper ends 40a of a pair of braces 40, 40 and are double-shear joined with a single bolt 7 and nut 8, and the upper corners 35b of the gusset plates 35 are clamped between the lower ends 40b of a pair of braces 40, 40 and are double-shear joined with a single bolt 7 and nut 8.

Furthermore, as shown in Figures 12 and 16, at the midpoint between both ends of the cross beam 26 and the adjacent left and right columns 11, 11, the upper part 36b of the gusset plate 36 is clamped between the lower ends 40b of a pair of braces 40, 40 and joined in double shear by a single bolt 7 and nut 8. Furthermore, the lower part 36c of the gusset plate 36 is clamped between the upper ends 40a of the pair of braces 40, 40 and joined in double shear by a single bolt 7 and nut 8.

In this way, by sandwiching the gusset plates 30, 35, 36 between a pair of braces 40, 40 and connecting them in double shear with a single bolt 7, it is possible to improve shear strength and ensure high seismic isolation and earthquake resistance for the combined wooden and light-gauge steel frame building. In other words, compared to conventional gusset plates connected in single shear with two bolts to the end of the brace, it is possible to achieve double the strength, and it is possible to significantly improve the high seismic isolation and earthquake resistance of the combined wooden and light-gauge steel frame building 1 with fewer bolts.

Furthermore, as shown in Figure 2, at each diagonal corner 20 between the sill 21 (the lower cross member) and the cross beam 26 (the intermediate cross member) and between adjacent left and right columns 11, 11, a pair of braces 40, 40 are arranged in an X-shaped cross configuration, thereby reducing (halving) the load (stress) that the cross members 21, 22, 26 bear from the column 11. More specifically, in section G of Figure 2, the tensile axial force received from the lower end 40b of the brace 40 is not transmitted vertically (upward) to the column 11, but is transmitted to the upper end 40a of the brace 40, and both are transmitted horizontally (to the right) to the cross beam 26. In section E of Figure 2, the vertical axial force (downward) is transmitted to the column 11, and the tensile axial force is transmitted to the upper end 40a of the brace 40. At section B in Figure 2, a vertical axial force (upward) is transmitted to column 11, and a horizontal force (rightward) is transmitted to foundation 2. Furthermore, because a load (downward) exists at the column capital of column 11, reduction occurs in both the vertical and horizontal directions. At section A in Figure 2, a vertical axial force (upward) is transmitted to column 11, and a horizontal force (leftward) is transmitted to foundation 2. Furthermore, because a load (downward) exists from section C to section E of column 11, reduction occurs in both the vertical and horizontal directions. In addition, horizontal forces at section B (rightward) and section A (leftward) are reduced in both the horizontal and vertical directions. Therefore, stress can be reduced (by up to half) in each section. However, although partial load stress occurs in the column 11, girder, beam 22, and foundation 2, all of these are below the allowable stress (proof strength) range.

The present embodiment has been described above, but it is not limited to this, and various modifications are possible within the scope of the gist of the present embodiment.

In other words, in the above embodiment, the C-channel steel members that make up the columns, beams, etc. are bolted back to back, but they may also be bolted with buffer material interposed between them.

Furthermore, according to the above embodiment, a pair of braces is arranged in an X-shape and connected via gusset plates to each diagonal corner of the frame on the wall side, but it is also possible to arrange a pair of braces in an X-shape and connect via gusset plates to each diagonal corner of the frame on the floor (horizontal surface) side.

1 Wooden and lightweight steel frame combined building 2 Foundation 3 Anchor bolt 5, 7 Bolt 10 Earthquake-resistant and seismic isolation structure 11, 11' Column 12 C-channel steel material 13 Square column-shaped wood 15 Support mounting bracket 20 Corner 21 Foundation (lower cross member)
22 Girders or beams (upper or lower cross members)
23 C-channel steel 24 Girder or beam (upper cross member)
25 C-channel steel material 26 Cross beam (intermediate cross member)
27 C-channel steel material 30, 35, 36 Gusset plate 36d Notched portion (part)
40, 40 Pair of braces 40a Upper end 40b Lower end

Claims (5)

Gusset plates attached to each of the diagonally opposing corners between adjacent left and right columns and adjacent upper and lower cross members of a wooden and lightweight steel-framed building,
A pair of braces that are bolted together while sandwiching the gusset plates attached to each corner at both ends;
Equipped with
The gusset plate is sandwiched between the pair of braces and joined in double shear by the bolts ,
The column includes four C-channel steel members bolted to each other and a rectangular prism-shaped piece of wood inserted into each of the C-channel steel members,
A seismic isolation and earthquake-resistant structure for a building constructed using both wood and lightweight steel frames, characterized in that the cross member has two C-channel steel members bolted back to back . The seismic isolation and earthquake resistance structure for a combined wooden and light steel frame building described in claim 1, characterized in that a portion of the gusset plate is sandwiched between at least two of the four C-channel steel members and bolted in place. The seismic isolation and earthquake resistance structure for a combined wooden and light steel frame building described in claim 1 or 2, characterized in that the four C-channel steel members are fastened to anchor bolts protruding above the foundation via support mounting brackets bolted to each end on the foundation side. An intermediate cross member is attached to the intermediate position between the adjacent left and right columns arranged on each floor of the wooden and light steel frame combined building,
The seismic isolation and earthquake-resistant structure for a combined wooden and light steel frame building described in any one of claims 1 to 3, characterized in that the pair of braces are arranged so as to cross alternately in an X-shape between the adjacent left and right columns between the lower cross member and the intermediate cross member, and between the intermediate cross member and the upper cross member. Gusset plates attached to each of the diagonally opposing corners between adjacent left and right columns and adjacent upper and lower cross members of a wooden and lightweight steel-framed building,
A pair of braces that are bolted together while sandwiching the gusset plates attached to each corner at both ends;
Equipped with
The gusset plate is sandwiched between the pair of braces and joined in double shear by the bolts ,
An intermediate cross member is attached to the intermediate position between the adjacent left and right columns arranged on each floor of the wooden and light steel frame combined building,
A seismic isolation and earthquake-resistant structure for a combined wooden and lightweight steel frame building, characterized in that the pair of braces are arranged alternately in an X-shape between the adjacent left and right columns between the lower cross member and the intermediate cross member, and between the intermediate cross member and the upper cross member.