Appendix A8_Excerpts from Project Delivery Strategy -Tower

Richard

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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

11.1 Time Analysis of External Skin, Table 1 and Table 2 – 8 pages .............................................................. 149

11.2 Time Analysis of Internal Skin, Table 1 and Table 2 – 6 pages ................................................................ 158

11.3 Sketch on Normal Work Flow for Working Design Stage – 2 pages ......................................................... 165

11.4 Sketch 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.