Appendix A8_Excerpts from Project Delivery Strategy -Tower

APPENDIX A8
EXCERPTS FROM PROJECT DELIVERY STRATEGY
FOR OKHTA TOWER FACADE

OKTHA CENTER 1Project Delivery Strategy -Tower
10/5/2013 – R. D. Ochotorena
1 TABLE OF CONTENTS
1 TABLE OF CONTENTS........................................................................................................................................ 1
2 INTRODUCTION................................................................................................................................................... 3
3 ANALYSIS ON THE PROEKT SUBMISSION DOCUMENTS............................................................................... 4
4 DESCRIPTION OF THE TOWER AND TOWER FAÇADE................................................................................... 5
5 ENGINEERING PRINCIPLE OF THE TOWER FAÇADE..................................................................................... 8
6 THE EXTERNAL SKIN OF THE TOWER FAÇADE.............................................................................................. 9
7 MANAGEMENT STRATEGY FOR THE OVERALL FAÇADE WORKS.............................................................. 15
7.1 Strategy for the Working Design Stage....................................................................................................... 15
7.1.1 Façade Consultants........................................................................................................................ 15
7.1.2 Independent Checking and Endorsing Engineer whose functions are as follows: ......................... 16
7.1.3 Cost Consultants ............................................................................................................................ 16
7.1.4 Façade Testing Consultant............................................................................................................. 16
7.2 Strategy for the Façade Fabrication and Installation Stage........................................................................ 17
7.2.1 Façade Installation and Project Engineering Consultant................................................................ 17
7.2.2 Surveying Consultants.................................................................................................................... 17
7.2.3 Independent Testing Consultants for specific items/components of works such as (welds, anchor
shear and pull-out test and other similar tests usually done on site).............................................. 17
8 OKTHA TOWER FAÇADE INSTALLATION STRATEGY WITH SAFETY ASSESSMENT AND PROPOSED
SAFE WORK METHODS................................................................................................................................... 18
8.1 Logistics (Moving, Handling and Storing Façade Units)............................................................................. 19
8.1.1 Design and Fabrication of Façade Units......................................................................................... 19
8.1.2 Packaging of Assembled Façade Units.......................................................................................... 19
8.1.3 Construction Platforms for Loading and Unloading of Materials..................................................... 21
8.1.4 Storing Façade Units on Tower Floors ........................................................................................... 26
8.1.5 Moving of Façade Units to Location of Installation......................................................................... 28
8.1.6 Additional Safety Precautions for Material Handling....................................................................... 30
8.1.6.1 Crates/Stillages.................................................................................................................. 30
8.1.6.2 Lifting Gears for Handling and Hoisting of Crates/Stillages............................................... 30
8.2 Basic Safety Procedures to Comply to Minimum Safety Requirements..................................................... 36
8.2.1 Additional Safety Precautions for Material Handling....................................................................... 36
8.2.2 Safety Guide for Fall Protection in Working at Heights................................................................... 37
8.2.3 Competency of Employees Working at Height ............................................................................... 38
8.2.4 Guidelines on Hierarchy of Control Measures for Working at Height ............................................. 38
8.2.5 Minimum Safety Procedures and Requirements for Safe Works ................................................... 40
8.2.6 Summary of steps to take before working at height........................................................................ 44
8.2.7 Minimum Safety Requirements for the Façade .............................................................................. 45
8.3 Configuration of the External Skin of the Tower Façade ............................................................................ 48
8.4 The Ring Beam Option ............................................................................................................................... 50
8.4.1 Description...................................................................................................................................... 50
8.4.2 Method of Installation – Ring Beam Option .................................................................................... 54

8.4.3 Modulation of Steel Sub Frame for Ring Beam Option................................................................... 61
8.4.4 Modulation of Façade Units for Ring Beam Option ........................................................................ 67
8.5 The Gerber Option...................................................................................................................................... 74
8.5.1 Description...................................................................................................................................... 74
8.5.2 Method of Installation – Gerber Option........................................................................................... 81
8.5.3 Modulation of Steel Sub Frame for Gerber Option ......................................................................... 86
8.5.4 Modulation of Façade Units for Gerber Option............................................................................... 93
8.6 Ring Beam Option versus Gerber Option................................................................................................... 99
8.6.1 Safety Appraisal.............................................................................................................................. 99
8.6.1.1 Ring Beam Option ............................................................................................................. 99
8.6.1.2 Gerber Option.................................................................................................................... 99
8.6.2 Installation time............................................................................................................................. 101
8.6.2.1 Ring Beam Option ........................................................................................................... 103
8.6.2.2 Gerber Option.................................................................................................................. 104
8.6.3 Comparison on Cost..................................................................................................................... 105
8.6.3.1 Ring Beam Option ........................................................................................................... 105
8.6.3.2 Gerber Option.................................................................................................................. 108
8.6.4 Conclusion.................................................................................................................................... 110
8.7 The Internal Skin of the Tower Façade..................................................................................................... 111
8.7.1 Description.................................................................................................................................... 111
8.7.2 Method of Installation – Internal Skin............................................................................................ 117
8.7.3 Modulation of Façade Units – Internal skin................................................................................... 119
8.7.4 Installation time for the Internal Skin............................................................................................. 124
9 MAINTAINABILITY............................................................................................................................................ 126
9.1 Tower Façade........................................................................................................................................... 126
9.2 Internal Skin.............................................................................................................................................. 139
9.3 Glass Replacement and other Heavy Maintenance Work........................................................................ 143
9.3.1 Glass replacement – External Skin............................................................................................... 143
9.3.2 Glass replacement – Internal Skin................................................................................................ 144
10 PROGRAM ANALYSIS..................................................................................................................................... 145
11 APPENDICES................................................................................................................................................... 149
11.1Time Analysis of External Skin, Table 1 and Table 2 – 8 pages .............................................................. 149
11.2Time Analysis of Internal Skin, Table 1 and Table 2 – 6 pages................................................................ 158
11.3Sketch on Normal Work Flow for Working Design Stage – 2 pages......................................................... 165
11.4Sketch on Optimize Work Flow for Working Design Stage – 1 page........................................................ 168

2 INTRODUCTION
The following report was to develop to summarize the constructability of the Façade Works of the OKHTA
Center Project Phase 1. The base time line for this report will be the current progress on the overall project
program of the works, based on the current contract of the General Designer to develop design documents for
Proekt Stage P Submission which also includes additional information which will confirm that the design for the
project will be workable and usable for further development during the Working Design Stage (WSD). To
simplify, we will call this stage the Proekt Stage P design phase.
By definition, the Proekt Stage P design development is the taking the concept design previously envisioned by
the General Designer (usually the Architect) for the project and develop this to a stage that the concept design
is fully justified to comply with architectural and engineering principles, and National Standards for design and
construction which will be reviewed by Building Officials for approval prior to the development of design
documents which will be used for construction. Further, the Stage P documents also includes an established
scheme on how the project will be constructed in order to justify that the structure will be buildable and yet still
this design documents will be fully confirm during the WSD of the Construction Stage.
Prior to Construction Stage the Proekt Design Documents will undergo review and further design development
to confirm that the design envisaged by the General Designer is workable in order for the Project Contractor will
agree to build the structure and upon completion provide confirmation and guarantee that the structure will
perform as it is envisioned by the General Designer and as expected by the Client.

procedure to the façade installation works will defeat the over-all objective of the project which
will not have favorable results or acceptance to the Developer or Client.
A minimum safe working zone is defined as area on an established distance from the edges of
the building extending inward to inside of the building on where the façade installers can freely
move during execution of their assigned works. The minimum safety working zone is the
primary safety requirement for façade installation and to the works done on the edges of the
building.
In order to prevent the workers to accidentally fall over the edges of the building during
execution of their assigned work, the means of controlling their movements should be provided.
In controlling the operatives’ movements to maintain their position within the minimum safety
working zone; the operatives are required to wear a full body safety harness as a compulsory
requirement for them to be allowed to work on the building edges. The full body safety harness
are clipped to latch way cable systems or safety lines on where anchors are provided before
hand as a minimum safety requirement prior to the façade works.
In normal (or typical) high rise construction, in order to prevent other operatives or non-building
edge working people to enter the minimum required safety zone, guard rails which are
structurally design to withstand impact and live loads shall be provided. These guard rails are
critical in separating non-building edge working operatives to go into the working space and
disturb the attention of façade installers or other edge of buildings operatives which might cause
accidental falling over the edges.

Minimum safe working zone for typical high rise project
The decision to establish a minimum safe working zone for a project will depend predominantly
on the working habit or attitude of the operatives working on the project and the region where
the project is located. The location of guard rails are also affected by the same reasons for the
establishment minimum safety zones. In normal (or typical) high rise construction at locations
where economy can sustain continuous construction works or projects, operatives who are
assigned in working at building edges are fully trained and those who have experiences are
maintained. Therefore such operatives are already familiar with the mechanics of a minimum
safety working zone of which a sample of a minimum safety working zone is shown in the figure
above.

Since the economy of the location of this project (Okhta Center Project) does not sustain
continuous construction works, therefore the operatives are not fully trained and experienced in
working at edges. Due to this reason it is therefore recommended that in order to prevent
accidental fall from edges, the re-arrangement of the minimum safety working zone, location of
guard rails and fall restraint system are being proposed, please see sketch below.
Proposed minimum safety requirement to be established and provided prior façade installation.
In the figure above the guard rails will be situated at a distance near the slab edges as the
primary safety structure to prevent fall from edges in case of failure of the primary safety
structure an additional fall arrest system will be the secondary safety system to prevent fall.
8.3 Configuration of the External Skin of the Tower Façade
The configuration of the tower façade as described by the General Designer (Architect) of the project is
an Uninterrupted Hexagonal Layout which composed of triangular units that will form a hexagon
continuously compiled to the top of the tower. The following figures below shows the complicated nature
on how the tower façade is envisioned to be built by the General Designer.
Hand tools used during installation should be properly
tied to the installer to avoid accidental fall. Please
note that in the photo shown below safety helmet was
taken off due to obstruction of edge railing to avoid fall
of helmet upon hitting the obstruction.

Typical configurations of façade panels in one floor

Triangular patterns ultimately forming typical hexagonal shape of the tower facade
During the early stages of the design of the façade of the tower, there were doubts if the tower façade
can be build able due to its complicated configuration. Apart from its configuration there are also
questions or uncertainty on achieving the required efficiency of the façade in terms of its performance
aspects such as, weather tightness, thermal properties, structural reliability, constructability and energy
efficiency.
In order to satisfy the doubts that the façade can be build or not, the Client and the project team decided
to build a mock-up sample to resolve all the uncertainties as explained above. Another purpose of the
mock-up program was to demonstrate that the façade can be re-analyzed and re-developed through a
different approach by a prospective façade contractor to follow specified requirements established by the
General Designer.
The resulting configuration of unitized CW panels to form required hexagon as required by the General
Designer as analyzed by the winning façade contractor for the mock-up program can be referred to in
the following figure below.
Taking only the constructability of the façade, the mock-up program has successfully demonstrated that
the façade is build able using an approach usually used in a normal CW system of a typical and simpler
high rise building.
As a result of this mock-up program which is also a part of Stage P documents submission, the design
team had developed two options for constructing the tower façade, one the Ring Beam Option and the
Gerber Option. The differences of each option lies on how the façade units are structurally supported by
the steel sub frame or the “strong back” and how it interfaces to the main structure of the tower.
8.4 The Ring Beam Option
8.4.1 Description
The Ring Beam Option was the original approach developed by the General designer on how
the façade will be supported by a steel sub frame or a “strong back”. The main principle as

conceived by the General Designer for the Ring Beam Option is that the façade units (or the
aluminum curtain wall units) will be supported by a stainless steel structure that follows the
configuration of the façade which is the uninterrupted hexagonal mullion lay-out. This stainless
steel sub frame or the “strong back” will be responsible in absorbing the service loads and carry
the self-weight of the steel and the façade leaving the rain screen and thermal performances as
the function of the façade closure. The Ring Beam steel sub frame will act like a truss like
structure due to the triangular modules that makes the hexagonal configuration and since it is
supported only at two points it will minimize the deflection on the edge beam of the main
structure where it will be hanged. The sketches and principle details developed for the Stage P
submission on the Ring Beam Option are shown in the following figures below.
Principle sketch for the Ring Beam Option which follows the configuration of the tower façade
showing extent warping of the facade due to twisting

Typical Mullion Detail
Intermediate Mullion Detail

Typical Stack Joint for the façade units in between floor levels
Typical Stack Joint at Floor levels

Detail of interface to the main structure
8.4.2 Method of Installation – Ring Beam Option
As previously mentioned, there are two structural systems for the structural steel sub-frame
developed to support the façade units for the façade of the tower. One developed by the
General Designer (Ring Beam Option) and one developed during façade mock-up program for
testing (Gerber Option) which is shown in the figure below.

Proposed structural systems for the steel sub-frame of the tower facade
Both structural systems had similar repetitive installation sequence which is typical to a normal
facade construction, which is to hang the façade structure and in this case separately, the steel
sub frame on each floor of the main structure independent to each other giving allowances to
movements and deflections due to self weight and other secondary effects such as shrinkage,
creep and others.
The method of installation can be summarized in the included figure below.

Typical installation sequence using tower crane for installing steel sub-frame

After installing the steel sub frame or support structure consequently the installation of the
façade units will follow. There are two ways to install the façade units depending on the
modulation of the façade units but both primarily deals on how to hoist the façade units to the
location of installation on the steel sub frame. The differences are on what equipment will be
used in hoisting and how efficient it will be in hoisting the equipment up the tower. One will be
the use of a portable crane, the other by chain hoist and monorail system. The following figure
shows each of the equipment work in hoisting façade units.

It should be noted in the figure above that the safe way of preparing the façade units from the
storage area on the floor to the hoisting area to where the façade units will be installed will have
to be finalized with the façade contractor since each contractor will have different system of
maneuvering façade units during and while hoisting.
Since the external sin of the tower façade had a vertical span of two storeys high, fixing of
façade units at high elevation will require elevated working platforms. Work at height can only
be safe in two ways either building a rigid platform or using MEWPs or Mobile Elevated Working
Platforms. Two types of MEWPs were proposed for use during installation of façade units,
photos of each of this type are shown in the following figures below.
Mobile Elevated Working Platforms to be used for installation of CW panels at mid height
vertical span height of the tower facade
Full Body Harness should be provided to
Employees Working at Heights and in MEWPs.
The use of a body belt is not acceptable.

MEWP scissor lift is to proposed to be used in working near the edges of the building
8.4.3 Modulation of Steel Sub Frame for Ring Beam Option
The sizes of the module of a steel sub frame critically depend on the capacity of the equipment
that will hoist the sub frame to its final location on the tower. In the originally approach, the
Ring Beam Options intends to hoist a fully assembled steel sub frame and install it to its final
location to the tower by the use of tower crane. The allowable safe working load or crane
capacity taking consideration all factors affecting its capacity such as weight of cables,
distances of supports and others, is at 3000 kgs (3 Metric Tonnes). This is based on the type of
crane proposed by the General designer in their Proekt Stage P documents, a sketch of which
was extracted and shown in the figure below.

The steel sub frame varies in sizes and in shape as it goes up the tower, which can be verified
in the figure below. Based on steel sizes shown in the previous details the average weight of
steel sub frame is at 103.56 kg/m^2. Therefore, a fully assembled sub frame will weigh at a
range from 9600 kgs to 14800 kgs depending on each location at the tower which cannot be
lifted by the tower crane.

In order to for the sub frame to be installed it is then proposed to assembling the sub frame in
smaller modules based on the capacity of the hoisting equipment. Optimized modules can be
configured similar to the one shown below on which connections can be designed for ease of
assembly to full configuration at the final location on the tower.

Sample calculation on one of the modules shown above limiting the weight to the capacity of
the hoisting equipment is shown on the table below.

8.4.4 Modulation of Façade Units for Ring Beam Option
For the Ring Beam Option, the façade units of the tower based on the original approach were
proposed to be assembled at full height of 8.4 meters, a configuration of which is shown in the
figure below.
Based on the details developed for the façade units, each of these full height modules will
weigh at 4227 kgs which also cannot be lifted by a tower crane. Even if it can be lifted by a
tower crane this will add to the load of the tower crane which might affect the overall logistics
schedule of the project. Further, it has been observed and verified through records that wind
often occurs at the project location especially during summer and autumn months. Wind
speeds are high during these times when work productivity should be at the highest, there is

considerable danger in lifting large panels above a certain wind speed which will put all the
hoisting works on hold resulting to delays on work schedule.
During the development of the façade design, such module was not fully analyzed and verified
for manufacturing constraints, since as previously described the tower façade is multi-faceted
which is not plane, therefore manufacturing large panels with different plane orientations within
the panels will require considerable effort in stabilizing the large panel making it rigid for
installation. Therefore, during the design development, the General Designer had only
assumed that this large panel assembly is only plane in order to provide an idea on the basic
approach for the constructability of the tower façade. The table below shows the verification
made on the weight of the façade unit described above.
Due to the limitation of the hoisting equipment, an optimized solution of modulation for the
façade is now being proposed. This optimized solution also does not take into account how
the façade units will be assembled, which is taking into account the orientation of the facets as
the façade goes up the tower.

The following sketches below shows the differences between the current Ring Beam Option
façade modulations to the proposed optimized version.

The largest façade unit of the optimize version weighs 2114 kgs which might be too much for
the capacity of a portable mobile crane, similar to the one shown in the figures below, if this
would be an option to hoist the façade units during installation. A portable crane is ideal for use
in hoisting smaller to medium sized façade units weighing from 400 to 1800 kgs. For heavier
façade units some other factors should also be taken into account when choosing an
appropriate portable mobile crane for us in the project. Factors such as weight of the mobile
crane punching through floors, moving such heavy duty portable mobile crane between floors of
installation and space required for extending the outriggers of the crane.

Required area for spread of spider legs for a heavy duty portable mobile crane
Table of information on portable mobile crane that can be accommodate the façade units described above
Another way of hoisting heavy façade units during installation is by using a chain hoist and
monorail system. This equipment is often used in high rise façade installation especially on
repetitive installation cycle of regular shaped façade units which counters the effects of the
costs of providing a railing system and installation of a support structure for the rails. The
downside of the system is that the support structure will also be constructed at the perimeter
edges of the building but proper development of the design and construction of the support

structure will counter the hazards of working at the edges of the building. Typical sketch of a
chain hoists and monorail system is shown in the figure below.

8.5 The Gerber Option
8.5.1 Description
As previously explained, the Gerber Option was developed during the mock-up program
development which will be included in the Stage P submission as a technical support
documents. The objective on which the mock-up program was to demonstrate that the facade
design that was developed by the General Designer for the project is constructible and
functions as it was intended. Further, it will also demonstrate and show that there are other
approaches on how to build the façade other than what was previously provided by the General
Designer in their current design documentations.
The Gerber Option had made some adjustments to the previous approach made by the General
Designer but had also satisfied the requirements set by them. It had made some improvement
in the amount of steel used in the Ring Beam Option by 40% by re-distributing the load to the
main structure. In terms of the design of the façade units there not much difference in
properties between the Ring Beam Option and the Gerber Option.
In order describe further sketches on principle details are shown below for reference and
comparison with the previous option.

Comparison of Gerber and Ring Beam Options for the Tower Facade

Typical Mullion Detail

Typical Stack Joint Detail

Intermediate Mullion Detail

Section Detail at the Interface with Main Structure (Support)

Plan Detail at the Interface with Main Structure (Support)

8.5.2 Method of Installation – Gerber Option
Both structural systems had similar repetitive installation sequence which is typical to a normal
facade construction, which is to hang the façade structure and in this case separately, the steel
sub frame on each floor of the main structure independent to each other giving allowances to
movements and deflections due to self weight and other secondary effects such as shrinkage,
creep and others. This system of hanging the façade is common or typical to ordinary façade
units and buildings of regular shape.
Proposed structural systems for the steel sub-frame of the tower facade
As with the Ring Beam Option, the Gerber Option also starts by hanging the steel sub frames
till one set is completed, subsequently the followed by the installation of the façade units
leaving out areas that is obstructed by hoisting structures.
Typical sketches of installing the steel sub frames and façade units are describe in the following
sketches.

Typical Sequence for installing steel sub frame for Gerber Option

Typical installation sequences and alternative methods of hoisting façade units

It should be noted in the figure above that the safe way of preparing the façade units from the
storage area on the floor to the hoisting area to where the façade units will be installed will have
to be finalized with the façade contractor since each contractor will have different methods of
maneuvering façade units during and while hoisting.
Since the external sin of the tower façade had a vertical span of two storeys high, fixing of
façade units at high elevation will require elevated working platforms. Work at height can only
be safe in two ways either building a rigid platform or using MEWPs or Mobile Elevated Working
Platforms. Two types of MEWPs were proposed for use during installation of façade units,
photos of each of this type are shown in the following figures below.
Mobile Elevated Working Platforms or MEWPS to be used for installation of CW panels at mid
height vertical span height of the tower facade
Full Body Harness should be provided to
Employees Working at Heights and in MEWPs.
The use of a body belt is not acceptable.

MEWP scissor lift is to proposed to be used in working near the edges of the building
In terms of safe work of installing the steel member and façade units the Ring Beam Option will
a good advantage as to compare to that of the Gerber Option. A summary of these
comparisons will be discussed later below.
8.5.3 Modulation of Steel Sub Frame for Gerber Option
The sizes of a module of a steel sub frame critically depend on the capacity of the equipment
that will hoist the sub frame to its final location on the tower. Instead following the configuration
of the façade as Ring Beam had followed, the Gerber Options had optimized the required steel
which also optimized the weight of the sub frame to a weight which can easily be handled by
the hoisting equipment or in this case the tower crane. Taking the allowable safe working load
or crane capacity at 3000 kgs (3 Metric Tonnes) which includes allowance for all factors
affecting its capacity such as weight of cables, distances of supports and others and based on
the type of crane proposed for Proekt Stage P documents, the Gerber Option optimize the steel
requirements by load re-distribution and utilization of strength of all components of the façade
structure.

Proposed type of crane for use on tower hoisting operations
Sketch on proposed optimization of steel sub frame used in the Gerber Option

The steel sub frame varies in sizes and in shape as it goes up the tower, which can be verified
in the figure below. Based on steel sizes shown in the previous details the average weight of
steel sub frame is at 61.262 kg/m^2. Each of the type main steel sub frame weighs at a range
from 1735 kgs to 1881 kgs depending on configuration which can be hoisted easily by the tower
crane.
Proposed configuration of steel sub frame used in the Gerber Option

Main steel sub frames of the Gerber Option
As applied on the tower a sample configuration of the Gerber Option and sample calculations of
the weight of the sub frame are shown in the following sketches.

Typical distribution of the Gerber Steel sub frame on the tower façade

8.5.4 Modulation of Façade Units for Gerber Option
For the Gerber Option, the façade units as proposed are of smaller sizes taking into
consideration the warping and twisting of the façade to form the facets. Further as previously
explained is has also considered utilizing the strength aluminum frames to minimize reliance on
the steel sub frame to resist the applied load for the façade. A sketch of the configuration of
façade units as proposed during the mock-up program is shown in the figure below. Each color
represents each façade unit or module.

Based on the details developed for the façade units, the largest of these modules will weigh at
1302 kgs which can hoisted by a portable mobile crane with capacity appropriate for the said
weight. Since the weight and sizes of the façade units are manageable, installation time can be
maximize even when appreciable wind speed occurs installation can still go on provide that
proper safety mitigation is applied in this prevailing weather condition.
The table below shows the verification made on the weight of the façade unit as described
above.

Appendix A8_Excerpts from Project Delivery Strategy -Tower

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