City of Mesquite General Design Standards Revision Date:

Transcription

1 SCREENING WALLS (Public and Private) Page 1 of 6

2 Section 1 General Design & Notes 1.1 Standards All screening walls in the City of Mesquite and within its Extraterritorial Jurisdiction (ETJ), both privately and publicly maintained, shall be designed and constructed in accordance with these General Design Standards The purpose of these standards is to provide design and construction standards for long-span precast concrete decorative screening walls that are extremely durable with extended service life, economical to maintain and aesthetically pleasing These standards are minimum design, construction and maintenance standards. All plans and specifications submitted for permit and construction shall be sealed by a registered professional engineer in accordance with the Texas Engineering Practice Act and Rules. All plans and specifications submitted for permit shall be accompanied by supporting design calculations, assumptions, code references and sketches clearly notated for ease of review by the City Engineering Division. Submitted supporting design calculations, assumptions and sketches shall be sealed by a registered professional engineer in accordance with the Texas Engineering Practice Act and Rules All screening walls and associated structural elements such as columns, piers, and pier caps shall be designed and constructed in accordance with ASCE 7-10, specifically Chapters 26 & 29 for wind design. Minimum design wind speed shall be 130 miles per hour (MPH) with the equivalent velocity pressure of pounds per square foot (PSF) Screening walls shall be located, designed, constructed and maintained in compliance with City of Mesquite Subdivision Ordinance and Zoning Ordinance requirements and specific development ordinances and agreements applicable to the property where the wall is being constructed Screening walls shall be designed, constructed and maintained in compliance with City of Mesquite Traffic Visibility and View Obstructions requirements (City of Mesquite Code of Ordinances, Part II, Chapter 9, Article X) Whenever screening walls are located on public right-of-way, easement, or other publicly owned property, the perpetual maintenance shall be assured by a viable property owners association to the satisfaction of the City Screening walls and mow strips shall be designed to accommodate through drainage if required by the drainage plans approved by the City Engineering Division. Page 2 of 6

3 1.1.6 Surface finish for all exposed surfaces on columns and panels shall be a form liner pattern finish that is to resemble stone, brick or other aesthetically pleasing pattern and must be approved by the City of Mesquite City Engineer. Section 2 Design Criteria 2.1 Placement of Screening Walls: The location, height and appearance of screening walls shall be approved as part of the Site Plan process Screening walls constructed within public rights-of-way shall be as close to the right-of-way line as possible without any encroachment of overhangs, foundations, piers or mow strips onto private property Screening walls placed on private property shall be placed in a screening wall maintenance easement a minimum of 5-foot in width. 2.2 General Materials and Colors: Screening walls shall be precast reinforced concrete with simulated brick, stone or other texture approved by the City of Mesquite and shall achieve the final effect of realistic stone, brick or other surface texture or design approved by the City Precast screening walls and associated elements and other product materials shall be from a City approved supplier and design from which replacement units are readily available to the City of Mesquite and shall be manufactured within the State of Texas All concrete for the precast screening wall panels, precast columns and associated elements such as drilled piers, pier caps, mows strips, column fill, etc. shall have a minimum compressive design strength of 4,000 PSI at 28 days, and shall contain a minimum of 6-sacks of cement per cubic yard of concrete Wall panels and columns shall include a texture/pattern approved by the City on each side. Pattern shall cover the entire face of panels exclusive of a maximum 1-foot wide border, if provided. Pattern shall cover the entire face of columns exclusive of a maximum 2-inch wide border, if provided. The City may require differing patterns on the two sides of the wall and different patterns for different segments of the wall Stone patterns shall incorporate an average relief of ½ minimum Brick patterns shall include a minimum ¼ relief at the bricks and 3 / 8 at any included border. Page 3 of 6

4 2.2.7 All exposed concrete surfaces shall be painted/stained with an approved water-based acrylic concrete paint/sealer to provide protection from rain, pollution and other elements and to achieve the desired natural stone, real brick or other City approved appearance Concrete surfaces shall be colored in the field after installation All stone patterns visible to the public shall be painted or stained to achieve a natural stone appearance and incorporate a base color and at least three accent colors All brick patterns visible to the public shall be painted or stained to achieve a real brick appearance including separate colors for mortar and brick Colors shall be earth tone. 2.3 Screening Wall Piers Reinforcing steel shall be minimum of six (6) #4 deformed bars conforming to ASTM A615 grade 60. Tie bars and spirals shall be minimum #3 bars. Reinforcing steel that extends into the columns shall meet the requirements of Section 2.6 Columns and be embedded in the pier a minimum of three (3) feet. The design drawing showing the reinforcing placement shall have a registered engineer seal and signature Piers shall be a minimum 18-inch diameter and penetrate a minimum of three (3) feet into solid rock as determined by the design engineer and confirmed by the City or bear on stiff clay at a minimum depth of twelve (12) feet The depth of the piers shall be determined by the design engineer and shall be shown on the signed and sealed design drawings The bottom of the drilled pier shaft shall be clean and dry prior to the placement of concrete Pier caps shall be a minimum twenty-four (24) inches square and at an elevation of no more than 2-inches below grade to no more than 8-inches above grade Concrete shall be placed within eight (8) hours after the pier shaft has been drilled. 2.4 Screening Wall Concrete Mow Strip The concrete mow strip between piers shall be at least as wide as the maximum outside dimension of the pier/pier cap and no less than 24 inches The concrete mow strip shall include a minimum of three (3) #4 steel reinforcing bars with 12-inch maximum spacing. Page 4 of 6

5 2.4.3 The concrete mow strip shall be a minimum thickness of 6-inches and be variable height to limit the gap between the wall panels and the mow strip finished grade to a maximum of 1½-inches. The mow strip must be formed above ground and a minimum of 6-inches below the finished grade at all locations Approved expansion material ¾-inch in thickness shall be placed on each side of the fence column pier caps where the concrete mow strip meets the pier caps The concrete mow strip shall include a City approved method to accommodate through drainage. Screening walls and mow strips shall be designed to accommodate through drainage if dictated by the drainage plans approved by the City Engineering Division. 2.5 Walls: Reinforcing steel shall be determined by a registered engineer and shall meet the requirements of ACI-318 or minimums specified herein, whichever is greater Wall panels shall be, at a minimum, continually reinforced along the top and bottom portions of the panels with deformed steel reinforcing bars conforming to ASTM A615 grade 60 with reinforcement provided being #4 bars or larger as required Wall panels shall be continually reinforced with a minimum of one mat of grade 60 welded wire conforming to ASTM A185 or A497 and attached to the top rebar with a minimum vertical and horizontal area of 0.08 in 2 /ft or larger as required The design drawing showing the reinforcing placement shall have a registered engineer seal and signature Minimum panel thickness shall be five (5) inches for rebar reinforced portions of the wall and three (3) inches for wire mesh reinforced portions of the wall Panels shall be uniform in finish, color and appearance and shall be readily interchangeable Curing of concrete panels shall be in accordance with the recommended practice of the Precast Concrete Institute of America Panels shall include loops for lifting with additional reinforcing at lift points adequate to support the weight of the panels during construction operations. 2.6 Columns: Columns shall be precast and a minimum eighteen (18) inches square. Page 5 of 6

6 2.6.2 Column minimum and maximum spacing shall be 12-feet and 15-feet, repsecitvely, between columns measured from the center of the column, except for end panels or at angle points which can be shorter as approved by the City Reinforcing steel shall be minimum #4 deformed bars conforming to ASTM A615 grade 60. Tie bars and spirals shall be minimum #3 bars. The design drawing showing the reinforcing placement shall have a registered engineer seal and signature Columns shall be connected to piers with a minimum of four (4) vertical #8 deformed steel reinforcing bars or a W4x13 steel I-beam post within a grouted hollow core of the pre-cast column. The reinforcing shall be sized according to the design engineer and embedded in the pier a minimum of three (3) feet. Rebar shall extend into full height of the column with a right angle bend at the bottom. I-beam posts shall be embedded a minimum of three (3) feet into the pier and extend into the column to half the height of the column Grout shall be a Portland cement non-shrink grout. 2.7 Column Caps: Column caps are required on all columns and shall include a lip that extends down over the column a minimum of one (1) inch to prevent lateral movement or affixed to the column by a method approved by the City Column caps shall be compatible with the wall and uniform in size and appearance. Page 6 of 6