SpencerHolmes
engineers - surveyors - planners
STRUCTURAL DESIGN
FOR
EMERGENCY CENTRE
AT
POTAE AVE
GISBORNE
FOR
GDC
Spencer Holmes Limited
57 Willis Street
PO Box 588
WELLINGTON
Reference 210934B01
Phone (04) 472 2261
September 2022
Document Control
SpencerHolmes
engineers - surveyors - planners
Emergency Centre
Potae Ave
GISBORNE
Ref.
Rev.
Description
By
Date
210934B01
A
TDS
09-09-2022
SECTION
Part A: Producer Statement
Part B: Design Features Report
Part C: Structural Calculations
Appendices
Site Investigation / Geotechnical Report
Action
Name
Signed
Date
Thomas Smith
Prepared by
Associate
09-09-2022
BE, CPEng, CMEngNZ, IntPE(NZ)
On behalf of
Spencer Holmes Limited
Spencer Holmes Limited
210934DFR
August 2022
Part A:
Producer Statement
Part B:
Design Features Report
Design Features Report
SpencerHolmes
engineers - surveyors - planners
Emergency Centre
Potae Ave
GISBORNE
1
GENERAL
Spencer Holmes Limited has been commissioned by Gisborne District Council to undertake structural
engineering design services for the proposed Emergency Centre located at Potae Ave, Gisborne.
1.1
Building Description
The proposed building is a single level building. The primary structure consists of timber trusses supported
on timber framed walls lined with sheet bracing. Plywood RAB on the exterior and GIB on the interior.
The foundations consist of the raised timber subfloor on shallow timber piles and anchor piles, with a
ground beam around the perimeter and through the centre of the building is both directions.
1.2
Objective
This Design Features Report (DFR) is a detailed document defining the design criteria for the primary
structure of this domestic dwelling. generally designed in accordance with B1/AS1 (NZS3604:2011)
by the architect, with elements of specific engineering design (SED) as indicated below;
Acceptable Solutions (B1/AS)
Specific Engineering Design (B1/ VM1 and VM4)
Site Inspections and Investigations
Geotechnical Engineering Report
Foundations
SED of Foundations
Beams/Lintels
SED of Beams/Lintels/Framing/Walls
Bracing
SED of Bracing
1.3
Scope
The structural engineering scope of the project is in accordance with the Design Brief and Conditions of
Engagement. In general terms, the scope of work being undertaken by Spencer Holmes Limited is as
follows;
• Design of the structure that is beyond the scope of NZS 3604, being specific design elements of
the foundations, gravity support, and bracing,
• Specification of NZS 3604 bracing elements (walls)
• Annotation of NZS 3604 primary structure (studs, rafters, joists, lintels, beams, bearers,
foundations) in order to aid architect in developing their plans.
• Detailing of the structural elements described above.
1.4
Design Standards
The following design standards are applicable to specific engineering design aspects of the building:
Acceptable Solutions (B1/AS)
Verification Methods (B1/VM1 and VM4)
Loads:
AS/NZS 1170
Loads:
NZS 1170
Timber:
NZS 3604
Concrete:
NZS 3101
Blockwork:
NZS 4229
Steel:
NZS 3404
Other:
Timber:
NZS 3603
Other:
Blockwork:
NZS 4230
Spencer Holmes Limited
210934DFR
August 2022
GDC Emergency Centre, Potae Ave, GISBORNE
Page 2 of 5
2
DESIGN LOADS
2.1
General
The design actions for this building are in accordance with AS/NZS 1170;
Importance Level
= 4
(Including SLS2 requirements)
Design Working Life
= 50 years
The ultimate limit state loads are to IL4 due to the proposed function of the structure as an emergency
centre.
2.2
Gravity Loads
The table below summarizes the typical material weights used for design.
Timber
Steel
Concrete
Soil
5.1 kN/m3
78.5 kN/m3
23.5 kN/m3
19.0 kN/m3
The table below summarizes the typical vertical gravity loads used for design.
Usage
Dead
Live
Roofs
0.40 kPa
0.25 kPa
Internal Floors
0.50 kPa
3.00 kPa
Walls
0.40 kPa
-
2.3
Wind Loads
The site is located on the in a “High” Wind Zone.
“High” is a non-specific wind zone specified in accordance with NZS 3604, with equivalent unfactored
wind speeds and pressures for specific engineering design as follows;
Ultimate Limit State
Serviceability Limit State
Direction of
Speed
Pressure
Direction of
Speed
Pressure
Approach
(m/s)
(kPa)
Approach
(m/s)
(kPa)
All
44.0
1.16
All
37.0
0.82
2.4
Snow and Ice Loads
Snow and ice are not significant loads for this building
Region: N1, < 400m
2.5
Seismic Loads
The seismic loads on this building have been determined by the following method;
NZS 1170.5:2004
Period, T1
= 0.4 s
(Single level timber framed building)
Site Subsoil Class
= D
(Soft or Deep)
Hazard Factor, Z
= 0.36
(Gisborne)
Ductility,
= 3.5
(Sheet Bracing)
3
Spencer Holmes Limited
210934DFR
August 2022
GDC Emergency Centre, Potae Ave, GISBORNE
Page 3 of 5
4
SERVICEABILITY CRITERIA
Particular elements are designed to the recommended serviceability deflection limits of AS/NZS
1170.0:2002, Table C1.
5
SOIL CONDITIONS
5.1
Site Soil Conditions and Bearing Pressure
Building Usage
Details
Geotechnical Report
Initia Report (Aug 2022)
6
DURABILITY
6.1
Design Life for Durability
Foundations and Superstructure
= 50 years
Non Structural / Cladding
= By others
Note: The design of non -structural elements and cladding specification are by the Architects and/or
Others and are not covered by this design features report.
6.2
Exposure Zones
NZS 3604
= Exposure Zone D (High)
NZS 3101
= Exposure Classification B2 (Coastal Perimeter <500m inland)
6.3
Durability Provisions
There is no effective verification method for B2 contained within the Building Code, however we can
confirm that for the structural elements shown in our documentation;
•
B2 Acceptable Solution for Structural Timber
NZS 3602 2003
Chemical preservation of round and sawn timber
NZS 3604 2011
Timber framed buildings
NZS 3640 Part 1:2003
Timber and wood-based products for use in building
Timber treatment is to be selected in accordance with Table 1A of B2/AS1. The timber treatment is to
be specified by the Architects and/or others.
•
B2 Acceptable Solution for Structural Concrete
NZS 3101 Part 1:2006
Concrete structures standards
Concrete covers have been selected in accordance with NZS 3101, Part 1, Section 3.
•
B2 Acceptable Solution for Structural Steel
SNZ TS 3404:2018
Durability requirements for steel structures and components
Steel protection has been specified in accordance with SNZ TS 3404 Table 6.
Spencer Holmes Limited
210934DFR
August 2022
GDC Emergency Centre, Potae Ave, GISBORNE
Page 4 of 5
7
MATERIALS SPECIFICATION
7.1
Reinforced Concrete
The following properties of concrete and reinforcing are applicable to the design:
Element
Concrete Strength
Typical Reinforcing
Foundations
25 MPa
Seismic 500E MA
7.2
Structural Timber
The following properties of structural timberwork are applicable to the design:
Element
Typical Grade
Special Grade
Roof Framing
SG8
-
Floor Framing
SG8
-
Beams / Lintels
SG8
-
Wall Studs
SG8
-
Bearers
-
Glulam GL12
Piles
SG8
-
8
PROPRIETARY SYSTEMS
The following proprietary structural systems included in the design of this building are:
Proprietary Timber Roof Trusses
Bracing Systems – GIB, Hardies, Ecoply
Other: Refer architect.
All proprietary products are to meet the performance requirements of the manufacturer’s specification. All
proprietary products should be installed strictly as per the manufacturer’s requirements unless noted
otherwise. The engineer is to be informed and is to confirm the use of any propriety product that differs
from what is shown on the plans or specification.
9
CONSTRUCTION SEQUENCE
Note: The excavation must NOT extend beyond the boundary without permissions.
The contractor shall have a construction methodology and an up to date programme prior to beginning
works on-site.
10
DESIGN DOCUMENTATION
10.1
Analysis
Analysis has completed using a combination of hand calculation, excel spreadsheets, and 2D/3D analysis
using Space-Gass computer software.
10.2
Documentation
Plans showing the structural elements overlayed on the Architectural drawings in Sketch Detail Format for
inclusion, and to be read with, the architectural drawings. Detailing of the structural elements in Sketch
Detail Format for inclusion, and to be read with, the architectural drawings.
Spencer Holmes Limited
210934DFR
August 2022
GDC Emergency Centre, Potae Ave, GISBORNE
Page 5 of 5
11
CONSTRUCTION MONITORING
11.1
Purpose of Construction Monitoring
As stated by the IPENZ document “Construction Monitoring Services”;
The primary responsibility for completing the contract works in accordance with the requirements of the
plans and specifications is the constructor's. The involvement of the consultants is important during the
construction phase to ensure that;
•
The design is being correctly interpreted,
•
The construction techniques are appropriate and do not reduce the effectiveness of the design and
•
The work is completed generally in accordance with the plans and specifications.
11.2
Construction Monitoring Level
The design is based on the verification of specific design B1/VM1 and VM4 aspects to the construction by
a suitably qualified Chartered Professional Engineer in accordance with ACENZ/IPENZ level CM3.
“Review, to an extent agreed with the client, random samples of important work procedures, materials of
construction and components for compliance with the requirements of the plans and specifications and
review important completed work prior to enclosure or on completion as appropriate. Be available to
provide the constructor with technical interpretation of the plans and specifications.”
“Not indicated is the time input requirement at each review. The time on each occasion will increase with
the increased size and complexity of the construction works and should be agreed with the consultant at the
time of engagement. Frequency of construction monitoring is intended to be indicative of involvement with
actual frequency dependent on the rate of progress of the works.”
11.3
Inspections
We confirm that Spencer Holmes Limited been engaged to undertake construction monitoring to the
recommended level above. The following inspections for specific design elements are required to meet this
level:
Pile inspection
Ground beam pre-pour (reinforcement) inspection
Inspection of non-specific design structural elements to NZS 3604:2011 such as floor slabs/foundations,
bracing, framing, and simple lintels generally undertaken by the Building Inspector for the Local
Territorial Authority.
Spencer Holmes Limited
210934DFR
August 2022
Part C:
Structural Calculations
Appendicies
