轻型框架墙的阻挡/支撑要求

Wood studs used in light-frame wall construction may require horizontally-oriented blocking for a number of reasons—including blocking at shear panel edges, 火阻塞, 受轴向载荷时的屈曲约束.

结构阻塞用途

阻塞减少螺柱长细比
第三节.7.1.4 of the American Wood Council’s 国家 Design Specification for Wood Construction (NDS) states that the slenderness ratio of studs shall not exceed 50 under in-service conditions or 75 during construction. This means that the maximum allowed weak-axis unbraced length for a 2x nominal wood stud is 6′-3″ (50 x1.5″)在工作条件或9 ' -4.5″ (75x 1.5″)在施工条件下. 然而, this doesn’t necessarily mean that solid wood blocking between the studs is required at these spacings in order to consider the studs adequately braced in their weak axis. Both interior and exterior wood wall construction commonly includes layers of wood structural panels (plywood or OSB) and/or gypsum wallboard. General practice is to consider these sheathing products and their attachments to the wood studs as adequate weak axis stud bracing, indicating that the NDS slenderness ratios could be met without the need for solid wood blocking between studs. 然而, 在建设中, it is common to have interior load bearing walls that are supporting construction loads from above but don’t yet have their gypsum wall board finishes installed. 在这种情况下，木块可能需要较高的墙壁.

A unique condition that exists in some interior walls is a staggered stud wall assembly, 哪里2×4木钉安装在2×6的顶部和底部板, 铆钉从盘子的一边到另一边交替安装. 这种壁面条件提供了极好的声学性能.

然而, 在这种情况下, only the outer faces of the studs are in contact with the sheathing and/or gypsum coverings; the interior faces of the studs are unbraced. NDS 2015附录A.11.3表示仅在螺柱的一面支撑是足够的:

When stud walls in light-frame construction are adequately sheathed on at least one side, 深度, 而不是螺柱的宽度, shall be permitted to be taken as the least dimension in calculating the le/d ra­tio. 的 sheathing shall be shown by experience to pro­vide lateral support and shall be adequately fastened.

类似的, NDS 2015 Figure 3F shows the unbraced column length based on bracing only on one face of the stud/column. NDS 2015评论.3.6.另外7个国家:

Use of 深度 of the stud as the least dimension in calculating the slenderness ratio in determining the axial load-carrying capacity of sheathed or clad light-frame wall systems is a long standing practice. 经验表明，木质结构板, 纤维板, 硬纸板, 石膏板, or other sheathing materials provide ad­equate lateral support of the stud across its thickness when properly fastened. 

In addition to considering the slenderness ratio limit of wood studs in their weak axis, 还应考虑承重螺柱的屈曲能力. 这在NDS第3节的柱稳定系数中得到了说明.7.1.5.

Although the code does not specify minimum blocking/bracing capacities in order to restrain this weak axis buckling, 通常的做法是，任何上述的护套系统, 标准紧固件时间表, 或实木挡在螺柱之间, 是否有足够的能力抵抗弱轴屈曲.

剪切板边

采用木结构剪力墙时, 通常把墙壁设计成闭塞的, resulting in significantly higher allowable shear capacities than unblocked shear walls. 当设计为阻塞时, all shear panel edges must fasten to a common framing member; these common framing members are usually vertically-oriented studs and horizontally-oriented blocking between studs. 第四节.3.6 of the American Wood Council’s Special Design Provisions for Wind and Seismic (SDPWS) provides requirements for these blocking members and this 木工问专家的帖子 discusses options for sizes and orientations of shear panel edge blocking.

阻火用途

的 《皇冠99hg现金网》 (IBC) has 火阻塞 requirements that are intended to limit the spread of flames, smoke and gases in combustible concealed spaces such as a wood-frame wall cavity. 这些要求包含在IBC 2015第718条中.2.2, state that 火阻塞 is required vertically at the ceiling and floor levels and horizontally at intervals not exceeding 10 feet. 此外，IBC第718条.2.3 requires that connections between horizontal and vertical spaces utilize 火阻塞 in order to prevent the passage of flame, 烟雾和气体从墙壁到连接的地板，反之亦然. In conventional light-frame wood construction where wall and ceiling finishes are installed tight to their associated framing members, 以及使用平台框架结构的地方, 墙壁的顶板将起到防火屏障的作用. 这一概念在IBC第718节的代码注释中得到确认.2.3. 然而, 在气球框架墙或下垂的软顶等情况下, 可能需要在墙上增加防火屏障. 请看下图，这是2015年IBC评论中的一个例子.

来源:国际建筑规范评论

最后, it is worth noting that the code allows the use of a number of products to function as 火阻塞. 除了实心2x标称木材成员, 其他选择包括双层1x标称木材, 碎料板, 石膏板和其他在IBC条款718中概述的产品.2.1.