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MPBZ Moment Post Base

MPBZ

The new patent-pending Simpson Strong-Tie® MPBZ is the first post base specifically designed to provide moment resistance for columns or posts and the first product in the industry to receive the ICC-ES code listing for moment resistance. An innovative overlapping sleeve design encapsulates the post, helping to resist rotation around its base. It is available for 4x4, 6x6 and 8x8 posts. The MPBZ is ideal for outdoor structures, such as carports, fences and decks. Built-in standoff tabs provide the required 1" standoff to resist decay of the post while eliminating multiple parts and assembly. Additionally, the MPBZ is available in ZMAX® as the standard finish to meet exposure conditions in many environments.

Key Features

  • Internal top-of-concrete tabs
  • 1" standoff tabs
  • Additional holes provided to attach trim material
  • Weep hole provided for water drainage

Material

  • 12 gauge

Finish

  • ZMAX® coating

Installation

  • Use all specified fasteners; see General Notes.
  • Install MPBZ before concrete is placed using embedment level indicators and form board attachment holes.
  • Place post on tabs 1" above top of concrete.
  • Install Simpson Strong-Tie Strong-Drive® SDS Heavy-Duty Connector screws, which are supplied with the MPBZ. (Lag screws will not achieve the same load.)
  • Concrete level inside the part must remain 1/4" or less above embedment line for water drainage.
  • Annual inspection of connectors used in outdoor application is advised. If significant corrosion is apparent or suspected, then the wood, fasteners and connectors should be evaluated by a qualified engineer or inspector.

Related Literature

Load Tables

Model No. Nominal Column Size Dimensions (in.) Simpson Strong-Tie SDS Screws Concrete Allowable Loads Wood Assembly Allowable Loads (DF/SP) Rotational Stiffness
Uplift (lb.) Lateral F1 (lb.) Moment M (ft.-lb.) Download (lb.) K
W1 / W2 D H Non-Cracked Cracked Non-Cracked Cracked Non-Cracked Cracked (100) (160) (in.-lb./rad.)
Wind and Seismic Design Category A&B
MPB44Z 4x4 3 9/16 7 1/4 7 1/4 (16) 1/4" x 2 1/2" 4900 3990 1825 1280 1410 985 6240 6410 2,510,000
MPB66Z 6x6 5 9/16 7 1/4 7 1/4 (24) 1/4" x 2 1/2" 5815 5815 3545 2480 2800 1960 9360 10855 3,950,000
MPB88Z 8x8 7 9/16 7 1/4 7 1/4 (36) 1/4" x 3" 9945 6960 7945 5560 4160 2910 15120 19230 7,776,000
Seismic Design Category C–F
MPB44Z 4x4 3 9/16 7 1/4 7 1/4 (16) 1/4" x 2 1/2" 4785 3350 1535 1075 1180 830 6240 6410 2,510,000
MPB66Z 6x6 5 9/16 7 1/4 7 1/4 (24) 1/4" x 2 1/2" 5815 5815 2980 2085 2055 1645 9360 10855 3,950,000
MPB88Z 8x8 7 9/16 7 1/4 7 1/4 (36) 1/4" x 3" 7420 6100 6965 4875 3470 2550 15120 19230 7,776,000
  1. Loads may not be increased for short-term loading.
  2. Higher download can be achieved by solidly packing grout in the 1"-standoff area before installation of the post. Posts bearing on grout must be naturally durable wood, preservative treated wood, or be installed with a moisture barrier between the post and grout. Allowable download shall be based on either the wood post design or concrete design calculated per code.
  3. Concrete shall have a minimum compressive strength, f'c = 2,500 psi.
  4. Tabulated rotational stiffness accounts for the rotation of the base assembly due to deflection of the connector, fastener slip and post deformation. Designer must account for additional deflection due to bending of the post.
  5. Multiply tabulated Seismic and Wind loads by 1.4 or 1.6 (1.67 for 2015 IBC) respectively to obtain LRFD capacities.
  6. In accordance with IBC Section 1613.1, detached one- and two-family dwellings in Seismic Design Category (SDC) C may use "Wind and SDC A&B" allowable loads.
  7. Foundation dimensions are for MPB anchorage only. Foundation design (size and reinforcement) by Designer.
  8. For loading simultaneously in more than one direction, the allowable load must be evaluated using the following equation: (Design Uplift/ Allowable Uplift or Design Download/Allowable Download) + Design Moment/Allowable Moment + Design Lateral/Allowable Lateral ≤ 1.0.
  9. Tabulated load values may be used for rough sawn lumber or larger size posts without reduction factors. Rough size and larger size posts shall be planed uniformly on all four sides such that center line of post is concentric with the center line of MPBZ.

Code Reports

Part IAPMO UES ER ICC-ES ESR City of Los Angeles State of Florida
MPB44Z ESR-2523 ESR-3050
MPB66Z ESR-2523 ESR-3050

ESR-2523 is an Index of many of Simpson Strong-Tie Stamped and Welded Cold-formed Steel Products for Wood or Cold-formed Steel Construction

Drawings

Part Orthographic Perspective
MPB44Z
MPB44Z Bottom View
DWG DXF
MPB44Z Front View
DWG DXF
MPB44Z Left View
DWG DXF
MPB44Z Right View
DWG DXF
MPB44Z Top View
DWG DXF
MPB44Z Perspective View
DWG DXF
MPB66Z
MPB66Z Bottom View
DWG DXF
MPB66Z Front View
DWG DXF
MPB66Z Left View
DWG DXF
MPB66Z Right View
DWG DXF
MPB66Z Top View
DWG DXF
MPB66Z Perspective View
DWG DXF
MPB88Z
MPB88Z Bottom View
DWG DXF
MPB88Z Front View
DWG DXF
MPB88Z Left View
DWG DXF
MPB88Z Right View
DWG DXF
MPB88Z Top View
DWG DXF
MPB88Z Perspective View
DWG DXF