Attachment 2 to OIA 2014 065 - Spencer Holmes Final Report on the RCC Building

SEISMIC STRENGTHENING REPORT

ON

GREATER WELLINGTON REGIONALCOUNCIL BUILDING

142-146 WAKEFIELD STREETWELLINGTON

FOR THE

GREATER WELLINGTON REGIONALCOUNCIL

Spencer Holmes LtdP O Box 588WellingtonPh (04) 472 2261 Ref E100961R02Fax (04) 471 2372 Revision 1 17-05-2012

Spencer Holmes Limited 100961r02 May 2012

SEISMIC STRENGTHENING REPORTGreater Wellington Regional Council Offices

142-146 Wakefield Street, WELLINGTON

Executive Summary

The Greater Wellington Regional Council (GWRC) buildings consist of a 10-storey tower blockconstructed along the Wakefield Street frontage to the property at 142-146 Wakefield Street and anindependent 5-storey car parking and office annex building constructed at the rear of the towerblock. For operational purposes the two buildings are one structure but are in fact separatebuildings. The buildings were designed in 1985 for Williams Property Holdings by Alun WilkieAssociates, Architects and D. J. Falloon, Consulting Engineer both of Christchurch and constructedshortly thereafter.

The lateral load resisting system of both the main tower and the car park building is reinforcedconcrete shear walls in both directions. The main tower has 2 walls in the east-west directionlocated either side of the lift core, and 2 walls in the north-south direction located on the west sideand within the lift core. The car park building has 2 walls in the east-west direction and 2 walls inthe north-south direction. The gravity support structure for both buildings consists of precast dycorefloor units with an insitu concrete topping slab. These precast units are supported on reinforcedconcrete beams and circular columns. There is a seismic separation of approximately 50mmbetween the upper floor levels of the two buildings. Both buildings are supported on concretefoundation beams with concrete bulb piles.

Spencer Holmes Limited completed an assessment report titled Seismic Assessment for theGreater Wellington Regional Council Building in June 2011. The report identified severalelements of structure and also non-structural elements that may not perform to the required 33%New Building Standard (NBS), where further study of these elements was recommended.

The original design intent for the building was for the concrete shear walls to behave in a ductilemanner and reach a sustained flexural yield without loss of significant strength. The as builtdetails of the shear walls, however, do not meet the current code requirements for this type ofbehaviour, and do not have sufficient shear reinforcing to meet the expected demand from capacitydesign and overstrength actions. Consequently the walls are not expected to behave in the ductilemanner assumed by the designer, but in a nominally ductile or more brittle manner where strengthis lost more quickly once flexural yield is attained. The seismic coefficient for nominally ductilestructures in the current design code is significantly higher than the seismic coefficient in the designcode used for this building, resulting in the low assessed strength of the shear walls relative to NewBuilding Standard (NBS).

Recent borehole investigations indicate that in a major earthquake there is a high risk that the upperstrata of soils above the pile founding depth will liquefy. The implications on the building structureare that liquefaction could lead to damage to the piles, gravity structure, and altering of theperformance of the shear walls, resulting in unpredictable behaviour of the seismic resisting system.

From the issues identified in the 2011 assessment report, and as a result of more detailedanalysis taking into account recent foundation investigations, the building is assessed as 30%of current code, and should now be considered earthquake prone and classified as grade D, orhigh risk, which requires improvement under the Building Act.

GWRC Offices Report, 142-1426 Wakefield St, Wellington Page 3


A review of the documentation for the existing building establishes the following factors, whichrequire careful consideration in the development of the strengthening system for the building;

Liquefaction of the upper 3 to 4 metre zone beneath the building foundations. Existing foundations and boundaries limiting potential locations for new foundations. Locating new seismic load resisting elements with consideration to functionality and

aesthetics of the building. Difficulty/impracticality of significant alteration works to the existing structural elements,

particularly in relation to fragility of the dycore floor system. Fragility and vulnerability of the existing dycore floor under significant interstorey drifts. Non-ductile nature of the 665-mesh topping slab reinforcement. Difficulty/impracticality to re-locate the existing stairs and lift well. Heavily over-reinforced characteristics of the existing concrete shear walls. Off-set of gravity resisting elements at the front of the building Inadequate seismic separation from the car park building.

Two options for upgrading the building have been considered;

1. Strengthening enhancements to achieve a minimum of 40% of current code compliance foran Importance Level 2 structure, and address specific structural inadequacies in order toremove building from earthquake prone building status. In this option the works can bestaged to progress on a floor-by-floor basis, allowing the majority of the building to beoccupied with tenants being temporarily relocated from floors undergoing works.

The extent of proposed seismic strengthening works to improve the building performance to40% of current code are as follows;

Fibre-reinforced polymer (FRP) strengthening to existing shear walls. FRP strengthening to existing concrete columns. FRP strengthening to surface of the upper concrete floor levels. Retrofit to underside of Dycore floor units with structural steel. Retrofit of central staircase with structural steelwork.

We have submitted the proposed extent of this strengthening option to the quantity surveyorRawlinsons Limited for preliminary estimates of cost (excluding GST), summarised asfollows;

Main Building $ 3,978,953Carpark Building $ 1,380,672TOTAL $ 5,359,625

On completion of these works the building would achieve an equivalent strength of40% of that required by NZS 1170.5:2004 for an importance level 2. This level ofstrengthening would improve the building such that it would be classified grade C, ormoderate risk.

2. Strengthening of the building to achieve 100% of current code compliance for anImportance Level 2 structure. Tenant occupancy of the building would not be permitted forthe level of works required in this option.



The extent of proposed seismic strengthening works to improve the building performance to100% of current code are as follows;

Tension anchors for existing shear walls. New piles, tension anchors and foundation beams for new shear walls. Grouting of the upper, susceptible soils to reduce the risk of liquefaction affecting

performance of the foundations. New concrete shear walls and columns. New ground floor slab, and new areas of upper concrete floor. Core drilling and Fibre-reinforced polymer (FRP) wrapping of existing shear walls. Retrofit to underside of Dycore floor units with structural steel. More extensive FRP strengthening to the surface of the upper concrete floor levels. New steel framed central staircase. New external cladding system, building services, ceiling grids and fit-out elements.

We have submitted the proposed extent of this strengthening option to the quantity surveyorRawlinsons Limited for preliminary estimates of cost (excluding GST), summarised asfollows;


On completion of these works the building would achieve an equivalent strength of100% of that required by NZS 1170.5:2004 for an importance level 2. This level ofstrengthening would improve the building such that it would be classified grade A, orlow risk.

A strengthening option to achieve 67% of current code was not developed, as once strengtheningbeyond 40% is required, the structural elements similar to that required in the 100% scheme willthen be required.

Report prepared by: Report reviewed by:

Vaughan England Peter C SmithSenior Structural Engineer DirectorBE (Hons), GIPENZ BE FIPENZ CPEng IntPE



Brief

Spencer Holmes Limited has been commissioned by the Greater Wellington Regional Council(GWRC) to provide further structural engineering advice in order to decide upon the future of theGreater Wellington Regional Council Centre buildings at 142 Wakefield Street, Te Aro,Wellington.

Limitations of this Report

This report has been prepared for the use of Greater Wellington Regional Council, and reliance bythird parties without the written approval of Spencer Holmes Limited shall be solely at that thirdparties risk.

The investigation carried out to enable the preparation of this report has been limited to a siteinvestigation, a review of the original drawings, a geotechnical report, and structural calculationssufficient to develop a proposed seismic strengthening scheme with sufficient detail for a quantitysurveyor to prepare estimates of cost. This report should also be read in conjunction with theSpencer Holmes Limited report 100961R01 titled Seismic Assessment for the Greater WellingtonRegional Council Building completed in June 2011.

Building Description

The GWRC buildings consist of a 10-storey tower block constructed along the Wakefield Streetfrontage to the property at 142-146 Wakefield Street and an independent 5-storey car parking andoffice annex building constructed at the rear of the tower block. For operational purposes the twobuildings are one structure but are in fact separate buildings.

For the purpose of reporting on the performance of each part of the building these are referred to inthe report as;

The GWRC Main Tower Building, (10-Storey Tower)

The GWRC Car park Building, (Adjacent 5-Storey Car Park and Office Building )

The building was designed in 1985 and built soon after, which was close to the peak period in thedevelopment boom prior to the Stock Market Crash November 1987. The building was designed inaccordance with the 1976 loadings code and/or the 1984 update however since then there has beensignificant advancement in loadings standards, material detailing requirements and understanding ofseismic performance.

The building was designed for Williams Property Holdings by Alun Wilkie Associates, Architectsand D. J. Falloon, Consulting Engineer both of Christchurch.



Background

GWRC BriefWe understand the Greater Wellington Regional Council requires further structural engineeringadvice on order to decide upon the future of the GWRC offices at 142-146 Wakefield Street. TheGWRC assessment will include the following options;

Do nothing Relocate to alternative premises Construct a new purpose built building Upgrade the existing building with either;

(i) staff remaining in the building but one or two floors being vacated at any time. Wherepractical, the upgrading work to take place after normal working hours.

(ii) Vacate the building while the upgrading work is carried out and return to the buildingon completion. This option provides an opportunity to reconfigure the use of thebuilding.

NZSEE Risk ClassificationFrom the conclusions of the 2011 assessment report, the building was classified as grade C, ormoderate-high risk with improvement and further investigation recommended. The riskclassifications are defined in the NZSEE guidelines Assessment and Improvement of StructuralPerformance of Buildings in Earthquakes as shown the table below;

The NZSEE also states:The elimination of non-ductile failure mechanisms and critical structural weaknesses is in itself ofgreater importance than the actual assessment and strengthening level. Building failures duringearthquakes rarely occur solely because the design forces have been underestimated. More oftenthan not, poor performance results from some obvious configurational or detailing deficiency.

As a result of more detailed analysis taking into account recent foundation investigations, thebuilding is now assessed as 30% of current code, and should now be considered earthquakeprone and classified as grade D, or high risk, which requires improvement under theBuilding Act.



Existing Building AssessmentSpencer Holmes Limited completed an assessment report titled Seismic Assessment for theGreater Wellington Regional Council Building in June 2011. Although the Greater WellingtonRegional Council Building is a relatively modern building, the structure (along with similarbuildings of the era) has some inadequacies with respect to seismic performance that are belowcurrent code requirements when reviewed with respect to the current code in 2011, and theadditional lessons learnt from the Christchurch Earthquakes.

This assessment has determined the performance of the main shear walls to be 30% of current codefor nominally ductile detailing, so the building should now be considered an Earthquake ProneBuilding in accordance with the legislation. The 2011 report also identified several elements ofstructure and also non-structural elements that may not perform to the required 33% New BuildingStandard (NBS).

Geotechnical InvestigationThe 2011 report highlighted that in a major earthquake there is a high risk that the upper strata ofsoils above the pile founding depth will liquefy. Liquefaction of these soils will greatly reduce theuplift capacity of the piles to and may lead to significant lateral movement of the building towardsthe waterfront. The implications on the building structure are serious and could lead to a potentialfailure of the piles, gravity structure, severe damage of the shear wall foundations, andunpredictable behaviour of the seismic resisting system.

Analysis of recent borehole investigations are summarised as follows:

The upper 3 to 4 metres of soil is loose, sandy and probably liquefiable. The material isunlikely to provide any uplift resistance for the piles.

From about 4 to 7 metres the soil is quite dense. This may be the bearing stratum given thatthe design drawings give the bearing depth for the Frankipiles as being 7 metres belowfinished floor level.

Below 7 metres the soils are mostly dense to very dense sandy gravels with some layers ofstiff silts. These materials are considered to be a low risk of liquefaction.

Precast Concrete StairsThe stairs to the building are located within the existing shear core of the structure and run parallelto the east side of the shear wall in the north-south direction. The stairs are detailed as scissorstairs with a mid-height landing.

Subsequent to the Canterbury earthquakes of 2010 and 2011, the Department of Building andHousing has published a Practice Advisory note titled Egress Stairs: Earthquake checks neededfor some. This advisory was issued in response to concerns about stair collapses in theChristchurch CBD buildings, and encourages building owners to have the stair design and detailingfor multi-storey buildings to be checked in regards to the issues relating to safety of stairs

Factors for Consideration in Development of Strengthening SystemA review of the documentation for the existing building establishes the following factors, whichrequire careful consideration in the development of the strengthening system for the building;

Liquefaction of the upper 3 to 4 metre zone beneath the building foundations.

Difficulty/impracticality of locating additional foundations other than tension piles.



Inadequate tension capacity of existing concrete piles.

Difficulty/impracticality in adequately connecting new shear walls into existing foundations.

Non-compliance of the brittle 665-mesh reinforcement in the topping slab of the floors.

Non-compliance of the edge strip of the dycore floor system.

Fragility of the dycore floor system.

Difficulty to re-locate the stairs and lift well.

Heavily over-reinforced characteristics of the existing concrete shear walls.

Inadequate connection of the existing shear walls to the adjacent floor structure.

High interstorey drift due to low stiffness of lateral load resisting systems.

Vulnerability of the dycore system to crack elongation at the end of the gravity frame underthe significant drifts that occur under earthquakes action in the existing structure.

Inability to stiffen shear walls without affecting functionality.

Difficulty in locating new shear walls between existing circular columns due to inability toprovide adequate additional confinement.

Difficulty in locating new shear walls without affecting functionality of building.

Difficulty in locating new shear walls without affecting aesthetics of building.

Significant loss of strength of the shear walls after spalling of concrete.

Offset of gravity resisting elements at the front of the building.

Inadequate inelastic resilience of the gravity load resisting system.

Inadequate seismic separation from the car park building.

Inadequate fixings of existing precast concrete panel cladding to structure.

Inadequate seismic bracing of the existing internal ceiling grids.



Strengthening Options

Two options for upgrading the building have been considered;

Option 1 - Strengthening enhancements to achieve a minimum of 40% of current codecompliance for an Importance Level 2 structure, and address specific structural inadequaciesin order to remove building from earthquake prone building status.

Option 2 - Strengthening of the building to achieve 100% of current code compliance for anImportance Level 2 structure. Tenant occupancy of the building would not be permitted forthe level of works required in this option.

A strengthening option to achieve 67% of current code was not developed, as strengthening beyond34% requires structural elements similar to that required in the 100% scheme to be installed.

Tables 3.1 and 3.2 of NZS1170.0 describe the importance level of buildings and are summarized inthe table below;

Level Importance Description1 Low Small, isolated - farm shed2 Medium Normal office building, house3 High Large capacity, important to community, non post-disaster4 Very High Post-disaster functionality - hospital, civil defence centre5 Special Dams

The seismic design loads for an Importance Level 3 building are 30% greater than that required forImportance Level 2, and for Importance Level 4 are 80% greater than that required for ImportanceLevel 2. We are of the opinion that these higher importance levels would not be achievable giventhe limitations of the site subsoils and the existing structural limitations of the building itself.

Option 1 - Strength Enhancement to 40% NBSThis option has explored the potential to enhance the inelastic behaviour of the existing lateral loadresisting system to the building. Simplistically, the strength of a building relative to NBS isdependent on two factors, adopted lateral load and assumed ductility relative to achievable ductility.The lateral load adopted for the design under an assumed ductility of the building can be comparedto the lateral load required by the current building code. A direct comparison of these loadsidentifies the strength reduction resulting from changes to the Building Code for an assumed levelof ductility.

The level of ductility achievable by the detailing of the structure has a significant influence on theassessed lateral load for a building. Previous design codes have been less specific over the detailingrequirements in order to achieve a culminated level of ductility. As a result, many structures weredesigned on an assumed ductility, the detailing of which was not achieved in practice. The failureto achieve a level of inelastic performance assumed in the selection of design criteria cansignificantly reduce the strength of a building relative to NBS. The lateral load resisting elementsin the building are over-reinforced and as a consequence, are vulnerable to shear failure prior toreaching their inelastic capacity.

For a building to achieve an assumed ductility, the walls not only need to develop their inelasticcapacity but need to be able to deform to a displacement of the ductility times the elasticdeformation at the onset of inelastic deformation. Improvement to the inelastic performance ofthese shear walls involves the cutting of sufficient vertical reinforcement within the tension zone



walls. The proposal also involves enhancement of the inelastic performance of the structure by useof fibre-reinforced polymer (FRP) to improve the shear resistance of the walls and enhance theconfinement of the compression zone of the walls.

In this option the works can be staged to progress on a floor-by-floor basis, allowing the majority ofthe building to be occupied. On the floor level undergoing works tenants would need to betemporarily relocated for the construction period.

The extent of proposed seismic strengthening works to improve the building performance toachieve at least 40% of current code is as follows;

Grouting of the upper, susceptible soils to reduce the risk of liquefaction affectingperformance of the foundations.

Core drilling and FRP wrapping of existing shear walls.

Provision of secondary support for the dycore floor units.

Enhancement of the floor diaphragms by the use of FRP surface treatments to collect thelateral loads and distribute the loads to the shear walls.

Enhancement of the gravity resisting system by improving confinement of columns.

Upgrading of stairs to the building, which are vulnerable to inter-storey deformations.

Upgrading of the pre-cast panel connections to external walls.

Reinstatement of any removed existing ceiling grids and fit-out elements.

Given these works a minimum equivalent strength of 40% of that required by NZS 1170.5:2004for an importance level 2 is achievable in the longitudinal and transverse directions.

Option 2 Strengthening Proposal to 100% NBSThis proposal involves the introduction of additional lateral load resisting elements of a similarform and proportion to the existing lateral load resisting elements in structures. The additionalelements not only strengthen the building, but also provide greater resilience against prematureinelastic behaviour of one or more of the existing lateral load resisting elements potentiallyintroducing excessive torsional response to the building under a moderate to severe earthquake.

After careful consideration, we are of the opinion that the preferred locations for additional lateralload resisting elements are as follows;

Northeast corner, by enclosing the open space with additional floor area.

Southwest corner, by demolishing and reinstating the existing floor structure.

Northwest corner, by partial demolition of the existing structure.

The locations above have been chosen because foundations can be introduced with limitedinterference from the existing foundations, effect on the internal functionality is minimal, and effecton enhancing the torsional performance is maximised.



Tenant occupancy of the building would not be permitted in this option due to the extent of works.

The extent of proposed seismic strengthening works to improve the building performance toachieve 100% of current code is as follows;

Grouting of the upper, susceptible soils to reduce the risk of liquefaction affectingperformance of the foundations.

New piles and tension anchors and foundation beams.

New concrete shear walls and columns.

New ground floor slab, and new areas of upper concrete floor levels.

Core drilling and FRP wrapping of existing shear walls.

Provision of secondary support for the dycore floor units.

Enhancement of the floor diaphragms by the use of FRP surface treatments to collect thelateral loads and distribute the loads to the shear walls.


Upgrading of stairs to the building, which are vulnerable to inter-storey deformations.


Install new external cladding, building services fit-out element.

Given these works a minimum equivalent strength of 100% of that required by NZS 1170.5:2004for an importance level 2 is achievable in the longitudinal and transverse directions.



Non-Structural Component Elements

GeneralThe structural design of all non-structural elements shall be in accordance with the New ZealandBuilding Act, and in particular accordance with:

AS/NZS 1170:2002 - Structural Design Actions NZS 4219:2009 - Seismic Performance of Engineering Systems for Buildings.

CeilingsDue to the extent of works required the existing ceilings would need to be removed and reinstatedwith new seismically braced lightweight ceiling grids. From observations of the Christchurchearthquakes, damage to the ceiling grid and loss of tiles was observed to be a problem even for newceilings with a level of engineering design to the current code. Consideration should be given torestraining ceiling tiles to remove the risk of obstructing the egress of staff in the periodimmediately following an earthquake.

Cladding SystemsDue to the extent of works required the existing precast concrete panels and windows would need tobe removed and reinstated as part of the external building envelope. It is recommended that all theprecast panel elements be removed to reduce the seismic weight of the structure.

The new window systems would consist of curtain wall glazing elements designed to withstand theanticipated elastic and inelastic deformations of the building under a moderate to severe earthquake.Such systems performed well in the Canterbury series of earthquakes. The new elements of non-structural exterior wall cladding are likely to consist of a either lightweight concrete speedwallsystem or pre-fabricated timber framed walls. The system needs to be carefully designed to allowconstruction in the confined space of the east wall.

Fit-out ItemsDue to the extent of works required the existing fitout to all levels would need to be removed andreinstated. High demand is expected on the partitions to the building with inter-storey drifts in amoderate to major earthquake event. Where the internal partitions are fixed from floor to floor,significant damage can be expected following a moderate to major earthquake Unless all shelving,desks, computer terminals, storage units, etc are effectively restrained they are a potential danger tostaff in a moderate to severe earthquake.

Other Services / Sprinkler SystemsThe adequate performance of the sprinkler systems and other services in a moderate to severeearthquake can only be assured when a rigorous and integrated approach to securing to the structureof the building and providing sufficient flexibility where required to accommodate buildingdisplacements is undertaken.

For example the failure to restrain ceiling tiles and sprinkler pipes can result in activation ofsprinklers that will result in water damage to the premises in a small to moderate earthquake. Thisresulting damage will result in less than desirable operational conditions following an earthquake.

It is our observation the services installation have been installed in an ad hoc manner over the last20 years rather than being considered in a total integrated manner, and therefore the performance isexpected to be varied. Due to the extent of works required much of the existing services would needto be removed and replaced. Similar criteria apply to the restraint of water, storm water, sanitarysewer and gas services.



Strengthening Design Parameters

Relevant Design Standards

AS/NZS 1170 Structural Design Actions NZS 3101:2006 Concrete Structures Standard NZS 3404:1997 Steel Structures Standard NZS 4219:2009 Seismic Performance of Engineering Systems for Buildings NZSEE Assessment and Improvement of Structural Performance of Buildings in

Earthquakes

Software Design Aids

ETABS 3D modal response analysis of loads and structural system behaviour. EXCEL Spreadsheets for repeated design of similar type.

Dead Loads

Floor Superimposed = 0.75kPa Self-weight of structural elements

Live Loads

Typical Office Floor = 3.0kPa

Seismic Load Parameters in accordance with NZS 1170.5:2004

Importance Level = 2 Design Working Life = 50 yearsSite Subsoil Class = D (deep or soft soil)Hazard Factor, Z = 0.40 Period, T = 1.3 secondsNear-Fault Factor, N(T) = 1.0 Spectral Shape Factor, Ch(T) = 1.6 Return Period Factor, Ru = 1.0

Structural Ductility Factors = 1.0 (floor diaphragms)= 3.0 (concrete shear walls)

Structure Type Structural Performance Factor, Sp Cd(T1) = 3.0 Limited Ductility 0.70 0.15

1.25 Nominal Ductility 0.93 0.471.0 Elastic 1.00 0.64

Seismic Design of Non-Structural Items

In accordance with the New Zealand Building Act, and in particular with NZS 1170.5:2004 andNZS 4219:2009.



Summary of Works

The extent of works required under the option 2 strengthening scheme is summarised approximatelyin sequence as follows;

Soft Demolition Remove existing fitout, ceilings and services not being retained. Removal of tenants would progress during this stage leading to zero occupancy of the

building during the works described below.

Structural Demolition Remove existing precast concrete panel exterior cladding and windows. Demolish existing concrete floor in southwest corner. Demolish existing cantilevered floor in northwest corner. Demolish existing ground floor slab. Demolish existing central precast concrete staircase.

Site Preparation Excavate below ground floor as required for new foundation works. Prepare surface of existing concrete elements for strengthening works.

New Foundation Works Install new piles and tension anchors. Complete ground enhancement works of grouting the upper liquefiable soil layers. Install new foundation beams.

New Concrete Works Install new concrete shear walls and columns. Place new ground floor slab. Install new areas of upper concrete floor levels.

Strengthening to Existing Shear Walls Core-drill through flexural reinforcement of existing walls. Core-drill through shear walls for anchorage of FRP wrapping. Install new FRP wrapping to end zones of shear walls. Install new shear strength enhancing FRP to face of shear walls.

Strengthening to Existing Floors Install new RHS steel seating support elements to underside of hollow core units. Install new FRP strengthening to surface of upper concrete floor levels.

Installation of New Central Staircase Install new steel framed central staircase.

Installation of Non-Structural Elements Install new external cladding systems Install new building services Install new ceiling grids and fit-out elements.

On completion of the works the building will achieve an equivalent strength of 100% of thatrequired by NZS 1170.5:2004 for an importance level 2.



Estimates of Cost

We have submitted the proposed extent of strengthening to the quantity surveyor RawlinsonsLimited for preliminary estimates of cost (excluding GST), summarised as follows;

Option 1 - Strength Enhancement to 40% NBS


Estimate InclusionsRawlinsons Limited has based their estimate costs on allowances for the following items;

40% strengthening work as described by Spencer Holmes. Preliminary & General costs; staged works 2 floors at a time. Main contractors margin. Estimating contingency. Professional fees. Demolition of 0.5m strip of ground floor slab adjacent to shear walls. FRP to face of existing shear walls. Reinstatement of 0.5m strip of ground floor slab adjacent to shear walls. RHS seating under ends of dycore floor units. FRP wrap of all existing concrete columns. 1.0 strips of FRP to floors and FLC to entire floor. Retrofit of existing staircase landings with structural steelwork. Integrated fitout and floor coverings reinstatement to 20% of fitout area only.

Estimate ExclusionsRawlinsons Limited estimates of cost have made no allowance for the following items;

Escalation and cost fluctuations beyond April 2012. Finance costs. Relocation or temporary accommodation of adjacent tenants. Light poles and street signage. Road closure costs. Development contributions, consent costs, disputes or objections. Legal fees. Goods and Services Tax. Insurance costs. Scaffolding. Full demolition of ground floor slab. New piles and anchors. Ground improvement sum. New foundation beams. New columns. New shear walls. New ground floor slab. Partial demolition of upper floors. Demolition of exterior precast panels.



Demolition of exterior faade. Demolition of precast stair. Core drilling and end wrapping of shear walls. 0.2m diagonal strips of FRP to floors. New cladding. New ceiling grid, HVAC, electrical and fire upgrade.

Option 2 Strengthening Proposal to 100% NBS


Estimate InclusionsRawlinsons Limited has based their estimate costs on allowances for the following items;

Strengthening work as described on Spencer Holmes Limited drawings provided. Ground enhancement works of $1,000,000 (excl GST). Building Construction. Full Refurbishment. Preliminary and general costs. Main contractor margin. Estimated contingency. Tenant fit-out. Professional fees.

Estimate ExclusionsRawlinsons Limited estimates of cost have made no allowance for the following items;

Escalation and cost fluctuations beyond April 2012. Finance costs. Relocation or temporary accommodation of adjacent tenants. Light poles and street signage. Road closure costs. Development contributions, consent costs, disputes or objections. Legal fees. Goods and Services Tax. Insurance costs.

GWRC Offices Report, 142-1426 Wakefield St, Wellington Appendix 1


APPENDIX 1Rawlinsons Preliminary Estimate of 100% Structural Strengthening, Upgrade and Fit-out



APPENDIX 2Rawlinsons Preliminary Estimate of 40% Structural Strengthening, Upgrade and Fit-out



APPENDIX 3E10-00961 Existing Drawings Main Building and Carpark Building



APPENDIX 4E10-00961 Proposed Schematic Drawings 100% Strengthening of Main Building

Attachment 2 to OIA 2014 065 - Spencer Holmes Final Report on the RCC Building

Documents

Transcript of Attachment 2 to OIA 2014 065 - Spencer Holmes Final Report on the RCC Building